Biomedical subjects

John D Friedman

Publications and source records attributed to John D Friedman.

At least 37 records · Page 2Linked to original sources

PubMed2004

Prognostic implications of atrial fibrillation in patients undergoing myocardial perfusion single-photon emission computed tomography.

OBJECTIVES: The aim of this research was to determine whether presence of atrial fibrillation (AF) provides incremental prognostic information relative to myocardial perfusion single-photon emission computed tomography (MPS) with respect to risk of cardiac death (CD). BACKGROUND: The prognostic significance of AF in patients undergoing MPS is not known. METHODS: A total of 16,048 consecutive patients undergoing MPS were followed-up for a mean of 2.21 +/- 1.15 years for the development of CD. Of those, 384 patients (2.4%) had AF. Cox proportional hazards method was used to compare clinical and perfusion data for the prediction of CD in patients with and without AF. RESULTS: Atrial fibrillation was a significant predictor of CD in patients with normal (1.6% per year vs. 0.4% per year in non-AF patients), mildly abnormal (6.3% per year vs. 1.2% per year), and severely abnormal MPS (6.4% per year vs. 3.7% per year) (p < 0.001 for all). By multivariable analysis, AF patients had worse survival (p = 0.001) even after adjustment for the variables most predictive of CD: age, diabetes, shortness of breath, use of vasodilator stress, rest heart rate, and the nuclear variables. In the 4,239 patients with left ventricular ejection fraction evaluated by gated MPS, AF demonstrated incremental prognostic value not only over clinical and nuclear variables, but also over left ventricular ejection in predicting CD (p = 0.014). CONCLUSIONS: The presence of AF independently increases the risk of cardiac events over perfusion and function variables in patients undergoing MPS. Patients with AF have a high risk of CD, even when MPS is only mildly abnormal. Whether patients with AF and mildly abnormal MPS constitute a group more deserving of early referral to cardiac catheterization is a question warranting further study.

Atrial Fibrillation↗

PubMed2004

Relationship between stress-induced myocardial ischemia and atherosclerosis measured by coronary calcium tomography.

OBJECTIVES: We assessed the relationship between stress-induced myocardial ischemia on myocardial perfusion single-photon emission computed tomography (MPS) and magnitude of coronary artery calcification (CAC) by X-ray tomography in patients undergoing both tests. BACKGROUND: There has been little evaluation regarding the relationship between CAC and inducible ischemia or parameters that might modify this relationship. METHODS: A total of 1,195 patients without known coronary disease, 51% asymptomatic, underwent stress MPS and CAC tomography within 7.2 +/- 44.8 days. The frequency of ischemia by MPS was compared to the magnitude of CAC abnormality. RESULTS: Among 76 patients with ischemic MPS, the CAC scores were >0 in 95%, >or=100 in 88%, and >or=400 in 68%. Of 1,119 normal MPS patients, CAC scores were >0, >or=100, and >or=400 in 78%, 56%, and 31%, respectively. The frequency of ischemic MPS was <2% with CAC scores <100 and increased progressively with CAC >or=100 (p for trend <0.0001). Patients with symptoms with CAC scores >or=400 had increased likelihood of MPS ischemia versus those without symptoms (p = 0.025). Absolute rather than percentile CAC score was the most potent predictor of MPS ischemia by multivariable analysis. Importantly, 56% of patients with normal MPS had CAC scores >or=100. CONCLUSIONS: Ischemic MPS is associated with a high likelihood of subclinical atherosclerosis by CAC, but is rarely seen for CAC scores <100. In most patients, low CAC scores appear to obviate the need for subsequent noninvasive testing. Normal MPS patients, however, frequently have extensive atherosclerosis by CAC criteria. These findings imply a potential role for applying CAC screening after MPS among patients manifesting normal MPS.

Coronary Artery Disease↗

PubMed2004

Stress myocardial perfusion single-photon emission computed tomography is clinically effective and cost effective in risk stratification of patients with a high likelihood of coronary artery disease (CAD) but no known CAD.

OBJECTIVES: We sought to evaluate the prognostic and cost implications of stress myocardial perfusion single-photon emission computed tomography (SPECT), or MPS, in patients with a high pretest likelihood (>0.85) of coronary artery disease (CAD) with no previous CAD. BACKGROUND: Sparse data are available regarding the prognostic performance characteristics of MPS in this patient group. METHOD: We followed up 1,270 consecutive patients with no previous revascularization or myocardial infarction (MI), with a pre-exercise tolerance test (ETT) likelihood of CAD > or =0.85, who underwent exercise or adenosine stress MPS (follow-up 94.4% complete; 2.2 +/- 1.2 years; 60 hard events [5.9%, 2.6%/year]). Risk adjustment of survival data was done using Cox proportional hazards analysis. Costs per reclassification of risk were calculated using assumed costs and threshold analyses. RESULTS: In patients treated medically after MPS, normal MPS had a low risk of cardiac death and hard events (0.6% and 1.3% per year, respectively). With increasing extent and severity of MPS defects, the risk of both cardiac death and hard events increased significantly (p < 0.05). Cox models indicated that the addition of MPS data resulted in incremental prognostic value over pre-MPS data (chi-square increase 48 to 87, p < 0.0001). Compared with strategies of initial referral to ETT in patients able to exercise, initial referral to MPS appeared to be a more cost-effective strategy. Similarly, compared with a strategy of direct referral to catheterization in patients with a high likelihood of CAD, initial referral to MPS is a cost-saving approach. CONCLUSIONS: In patients with a high likelihood of CAD but without known CAD, stress MPS yields incremental value and achieves risk stratification in a cost-effective manner. The current results support a strategy of initial stress imaging in this patient cohort, as a reasonable alternative to direct referral to catheterization or initial ETT.

Aged↗

PubMed2004

Prognostic relevance of symptoms versus objective evidence of coronary artery disease in diabetic patients.

AIM: Little is known about the prognostic significance of silent versus symptomatic coronary artery disease (CAD) in diabetic patients. We therefore assessed the incidence of scintigraphic evidence of CAD in diabetic patients without known CAD and the impact of symptoms and scintigraphic findings on prognosis. METHODS AND RESULTS: A consecutive series of 1737 diabetic patients without known CAD underwent dual-isotope myocardial perfusion SPECT (MPS) and 1430 were followed-up for a median of 2 (1-8.5) years. Critical events were defined as myocardial infarction or cardiac death. Objective evidence of CAD was found in 39% of 826 asymptomatic diabetic patients, in 51% of 151 diabetic patients with shortness of breath (SOB), and in 44% of 760 diabetic patients with angina. During follow-up, 98 critical events occurred. Annual critical event rates were 2.2% in asymptomatic, 3.2% in angina, and 7.7% in diabetic patients with shortness of breath ( p < 0.001 versus other groups). With MPS evidence of CAD, critical event rates increased to 3.4% (asymptomatic), 5.6% (angina), and 13.2% (SOB) ( p </= 0.009 versus no evidence of CAD). Age, hypertension, shortness of breath, scarring and ischaemia were independent predictors of critical events. MPS findings added incremental information to prescan information regarding outcome prediction. CONCLUSIONS: In asymptomatic diabetic patients, the rate of objective evidence of CAD and annual critical events were similar to those found in diabetic patients with angina. The outcome was three times worse in diabetic patients with shortness of breath. MPS findings were strongly predictive of outcome and proved valuable for risk stratification.

Aged↗

PubMed2004

Automatic quantification of myocardial perfusion stress-rest change: a new measure of ischemia.

UNLABELLED: In myocardial perfusion SPECT (MPS), ischemia is typically quantified as the difference between stress and rest defect sizes obtained by separate comparisons with stress and rest normal limits. Such an approach is not optimal because images are not compared directly with each other and a complex set of stress and rest normal limits is required. METHODS: We developed a fully automatic technique to quantify stress-rest change. We applied it to 204 patients whose SPECT images were acquired using a same-day dual-isotope (99m)Tc/(201)Tl protocol and on whom coronary angiography had been performed. A 10-parameter registration of rest and stress images was performed by an iterative search of best translational, rotational, scaling, and optimal stress-rest count normalization parameters. Identical stress-rest 3-dimensional left ventricle (LV) contours were automatically derived from stress images. Integrated deficit counts (normalized rest-stress) within the LV volume were derived from registered image pairs. A global measure of ischemia (ISCH) was calculated as the ratio of the total deficit stress LV counts to the total rest LV counts. RESULTS: Registration and derivation of quantitative measures were fully automatic. The average processing time was <40 s on a 2-GHz processor. When compared for prediction of stenosis, the area under the receiver operating characteristic curve (0.88 +/- 0.03) was significantly better for ISCH than that obtained by existing quantitative approaches, which use reference databases (0.80-0.82 +/- 0.03). The normalized stress-rest change could be visualized and localized directly on raw patient images using overlay display. CONCLUSION: Automatic stress-rest MPS image registration allows a direct estimation of ischemia from SPECT that does not require comparisons with normal limits.

Adenosine↗

PubMed2004

Influence of angiographic collateral circulation on myocardial perfusion in patients with chronic total occlusion of a single coronary artery and no prior myocardial infarction.

UNLABELLED: The functional role of various angiographic grades for coronary collaterals remains controversial. The aim of this study was to assess the influence of the Rentrop angiographic grading of coronary collaterals on myocardial perfusion in patients with single-vessel chronic total occlusion (CTO) and no prior myocardial infarction (MI). METHODS: The study included 56 patients with single-vessel CTO and no prior MI who underwent rest-stress myocardial perfusion SPECT and coronary angiography within 6 mo. All patients had angiographic evidence of coronary collaterals. Patients were divided according to the Rentrop classification: Group I had grade 1 or 2 (n = 25) and group II had grade 3 collaterals (n = 31). RESULTS: Group I had a higher frequency of resting regional wall motion abnormalities on left ventriculography (52.6% vs. 19.2% [P = 0.019]). The mean perfusion scores of the overall population showed severe and extensive stress perfusion defects (summed stress score of 14.1 +/- 7.1 and summed difference score of 12.9 +/- 6.9) but minimal resting perfusion defects (summed rest score of 1.0 +/- 2.7). No perfusion scores differed between the 2 groups. The perfusion findings suggested that chronic stunning rather than hibernation is the principal cause of regional wall motion abnormalities in these patients. CONCLUSION: In the setting of single-vessel CTO and no prior MI, coronary collaterals appear to protect against resting perfusion defects. Excellent angiographic collaterals may prevent resting regional wall motion abnormalities but do not appear to protect against stress-induced perfusion defects.

Aged↗

PubMed2004

"Motion-frozen" display and quantification of myocardial perfusion.

UNLABELLED: Gated myocadial perfusion SPECT (MPS) incorporates functional and perfusion information of the left ventricle (LV). To improve the image quality and accuracy of gated MPS we propose to eliminate the influence of cardiac LV motion in the display and quantification by a novel "motion-frozen" (MF) technique. METHODS: Three-dimensional LV contours were identified on images of the individual time phases. Three-dimensional phase-to-phase motion vectors were derived by sampling of the epi- and endocardial surfaces. A nonlinear image warping (thin-plate spline) was applied to warp all image phases to fit the end-diastolic (ED) phase. Warped images were created to provide the LV image in the ED phase but containing counts from an arbitrary number of time intervals. MF quantification has been performed using the same phase-to-phase motion vectors. MF normal perfusion limits were created from (99m)Tc sestamibi gated MPS studies of 40 females and 40 males with low likelihood (<5%) of coronary artery disease. All MF processing was completely automated. In the initial evaluation, we assessed the display quality and quantification of stress images using MF processing in 51 consecutive patients with 16-frame electrocardiographic gating and available coronary angiography. RESULTS: The display quality was significantly better for MF images as assessed visually. The MF images had the appearance of ED frames but were less noisy and of higher resolution than the summed images. MF images had higher maximum count values in the LV (116% +/- 6%) and higher contrast (12.5 +/- 7.7 vs. 9.5 +/- 3.2) than the corresponding summed images. The area under the receiver operator characteristic curve for prediction of stenoses > or = 70% by the MF method was 0.92 +/- 0.04 versus 0.89 +/- 0.04 by standard quantification (P = not significant). The computation time for automated MF quantification and warping was <25 s for each case. CONCLUSION: We have developed a novel technique for display and quantification of gated myocardial perfusion images, which retrospectively eliminates blur due to cardiac motion. Such processing of gated MPS appears to improve the effective resolution of images. Initial evaluation indicates that it may improve the accuracy of gated MPS in detection of coronary artery disease.

Aged↗

PubMed2004

Integration of automatically measured transient ischemic dilation ratio into interpretation of adenosine stress myocardial perfusion SPECT for detection of severe and extensive CAD.

UNLABELLED: The aim of our study was to derive and to validate the normal threshold for an automatically measured left ventricular transient ischemic dilation (TID) ratio in patients referred for adenosine stress myocardial perfusion SPECT (MPS) and to assess the value of integrating TID in detecting severe and extensive coronary artery disease (CAD). METHODS: Normal limits for the TID ratio were derived using dual-isotope MPS data from 38 patients with a low (<5%) likelihood of CAD. Criteria for abnormality were calculated on the basis of data from 179 consecutive patients who had undergone coronary angiography less than 3 mo after index adenosine MPS: 41 patients (23%) had severe and extensive CAD (> or =90% stenosis) in the proximal left anterior descending artery or in 2 or more coronary arteries, 64 (36%) had no significant CAD (<70% stenosis), and 74 (41%) had mild or moderate CAD. The criteria were then prospectively validated in a cohort of 177 patients, of whom 41 patients (23%) had severe and extensive CAD, 55 (31%) had no significant CAD, and 81 (46%) had mild or moderate CAD. RESULTS: By analysis of receiver-operating-characteristic curves, the best threshold for adenosine TID ratio abnormality was the mean adenosine TID ratio in the low-CAD-likelihood patients + 2 SDs (TID ratio > 1.36). Abnormal TID ratio using this threshold demonstrated high sensitivity and specificity for severe and extensive CAD (71% and 86%, respectively), and similar sensitivity and specificity were observed in the prospective validation group (73% and 88%, respectively). In the combined pilot and validation groups, the absence of both abnormal TID ratio and abnormal perfusion was highly specific for the absence of severe and extensive CAD; only one (1.3%) of 79 patients with severe and extensive CAD had neither of these abnormal findings on adenosine MPS. In patients with both abnormal TID ratio and abnormal perfusion, 55 of 84 (65%) had severe and extensive CAD. When patients had one but not both of these findings, 26 of 193 (13%) had severe and extensive CAD. CONCLUSION: The automatically measured TID ratio is a useful clinical marker that is sensitive and highly specific for identification of severe and extensive CAD in patients undergoing adenosine MPS. Integration of abnormal TID ratio into the dual-isotope MPS image interpretation algorithm improves the identification of severe and extensive CAD in adenosine MPS.

Adenosine↗

PubMed2003

Transient ischemic dilation ratio of the left ventricle is a significant predictor of future cardiac events in patients with otherwise normal myocardial perfusion SPECT.

OBJECTIVES: This study evaluated the prognostic value of transient ischemic dilation (TID) of the left ventricle (LV) in patients with normal stress myocardial perfusion single photon emission computed tomography (MPS). BACKGROUND: The prognostic value of TID in patients with an otherwise normal MPS has not been defined. METHODS: We identified 1,560 patients who had normal stress MPS (436 vasodilator and 1,124 exercise stress), and no rest LV enlargement (Population 1) and followed up for 2.30 +/- 0.67 years for hard events (HE) (cardiac death or myocardial infarction) and soft events (SE) (revascularization). Prediction of first HE or SE (total events [TE]) was evaluated by multivariable Cox analysis, which was also applied to a broader group of 2,037 patients (including patients with minimal defects (Population 2). RESULTS: In Population 1, there were 13 HE, 36 SE, and 42 TE. Patients in the highest TID quartile (TID > or =1.21) had a higher TE rate than others, regardless of stress type. By multivariable analysis, highest TID quartile was predictive of TE (p = 0.008). Other independent predictors of TE were age, typical angina, and diabetes. In Population 2, TID was also predictive of TE. CONCLUSIONS: An entirely normal stress MPS study does not always imply an excellent prognosis. In patients with otherwise normal MPS, TID is an independent and incremental prognostic marker of TE even after significant clinical variables--age, typical angina, and diabetes--are accounted for. When TID is present, caution in making low-risk prognostic statements may be warranted, especially in patients with typical angina, the elderly, and diabetics. Our findings also appear to apply to the broader population of "normal" MPS, which included patients with minimal perfusion defects.

Aged↗

PubMed2003

Is there a referral bias against catheterization of patients with reduced left ventricular ejection fraction? Influence of ejection fraction and inducible ischemia on post-single-photon emission computed tomography management of patients without a history of coronary artery disease.

OBJECTIVES: The objective of this work was to define the relationship between left ventricular perfusion/ function measures and referral rates to catheterization and revascularization early after stress gated myocardial perfusion single-photon emission computed tomography (MPS). BACKGROUND: Although revascularization yields the greatest survival benefit in patients with low ejection fraction (EF) and extensive coronary artery disease, referral patterns to catheterization and revascularization after noninvasive testing are not well defined. METHODS: We identified 3,369 patients without previous myocardial infarction or revascularization who underwent exercise or adenosine stress MPS and who were followed-up (97% complete) for occurrence of early (<60 days) post-single-photon emission computed tomography (SPECT) revascularization. Multivariable logistic regression modeling was used to determine the association of various patient characteristics and test results with performance of catheterization and revascularization as separate end points. RESULTS: In the first 60 days after stress MPS, 445 catheterizations (13.2%) and 254 revascularizations (7.5%) occurred, including 140 coronary artery bypass graft surgeries (4.1%) and 114 percutaneous coronary interventions (3.4%). Both post-stress gated EF and percent of the myocardium ischemic by stress MPS were independent predictors of revascularization. Logistic regression revealed that the likelihood of catheterization increased with both increasing ischemia and decreasing EF (c-index = 0.94, chi-square = 590). Predicted referral rates to catheterization increased with decreasing EF except in patients with severe ischemia (>15% of myocardium), where rates decreased with decreasing EF. Similar modeling of revascularization (c-index = 0.94, chi-square = 329) revealed that the likelihood of revascularization increased with increasing ischemia but, in general, decreased with decreasing EF. CONCLUSIONS: Although post-SPECT referral to both catheterization and revascularization is driven by ischemia, EF has the opposite effect on these two outcomes. Further studies evaluating the appropriateness of these referral patterns are warranted.

Adenosine↗

PubMed2003

Prognostic impact of hemodynamic response to adenosine in patients older than age 55 years undergoing vasodilator stress myocardial perfusion study.

BACKGROUND: The prognostic importance of various hemodynamic responses to adenosine infusion in patients undergoing adenosine stress myocardial perfusion stress (MPS) has not been defined. METHODS AND RESULTS: We identified 3444 unique patients (53.5% women, mean age 74.0+/-8.4 years) who underwent adenosine (with no additional exercise) stress myocardial perfusion single photon emission computed tomography (MPS) and were followed up for 2.0+/-0.8 years. Multivariable Cox proportional hazards analysis was used to assess the prognostic value of hemodynamic variables in predicting cardiac death (CD). Two hundred twenty-four CDs (6.5%) occurred during follow-up. By multivariable analysis, higher rest heart rate (HR) and to a lesser extent lower peak HR were markers of CD. When added to the multivariable model in place of peak and rest HR, the peak/rest HR ratio was an independent predictor of CD. Peak/rest HR ratio additionally risk-stratified patients within each MPS category. A significant interaction was found between gender and peak systolic blood pressure (SBP), in which there was an increased risk associated with a low peak SBP (<90 mm Hg at end of adenosine infusion) in men but not in women. CONCLUSIONS: Patients undergoing adenosine stress MPS with high rest HR and low peak/rest HR ratio have increased risk of CD, as do male patients with a low peak SBP. Assessment of the hemodynamic response to adenosine adds incremental prognostic value to MPS results and enhances identification of patients at risk for CD.

Adenosine↗

PubMed2003

Comparison of the short-term survival benefit associated with revascularization compared with medical therapy in patients with no prior coronary artery disease undergoing stress myocardial perfusion single photon emission computed tomography.

BACKGROUND: The relationship between the amount of inducible ischemia present on stress myocardial perfusion single photon emission computed tomography (myocardial perfusion stress [MPS]) and the presence of a short-term survival benefit with early revascularization versus medical therapy is not clearly defined. METHODS AND RESULTS: A total of 10 627 consecutive patients who underwent exercise or adenosine MPS and had no prior myocardial infarction or revascularization were followed up (90.6% complete; mean: 1.9+/-0.6 years). Cardiac death occurred in 146 patients (1.4%). Treatment received within 60 days after MPS defined subgroups undergoing revascularization (671 patients, 2.8% mortality) or medical therapy (MT) (9956 patients, 1.3% mortality; P=0.0004). To adjust for nonrandomization of treatment, a propensity score was developed using logistic regression to model the decision to refer to revascularization. This model (chi2=1822, c index=0.94, P<10-7) identified inducible ischemia and anginal symptoms as the most powerful predictors (83%, 6% of overall chi2) and was incorporated into survival models. On the basis of the Cox proportional hazards model predicting cardiac death (chi2=539, P<0.0001), patients undergoing MT demonstrated a survival advantage over patients undergoing revascularization in the setting of no or mild ischemia, whereas patients undergoing revascularization had an increasing survival benefit over patients undergoing MT when moderate to severe ischemia was present. Furthermore, increasing survival benefit for revascularization over MT was noted in higher risk patients (elderly, adenosine stress, and women, especially those with diabetes). CONCLUSIONS: Revascularization compared with MT had greater survival benefit (absolute and relative) in patients with moderate to large amounts of inducible ischemia. These findings have significant consequences for future approaches to post-single photon emission computed tomography patient management if confirmed by prospective evaluations.

Adenosine↗

PubMed2003

The metabolic syndrome, diabetes, and subclinical atherosclerosis assessed by coronary calcium.

OBJECTIVES: We compared the prevalence and extent of coronary artery calcium (CAC) among persons with the metabolic syndrome (MetS), diabetes, and neither condition. BACKGROUND: The prevalence and extent of CAC has not been compared among those with MetS, diabetes, or neither condition. METHODS: Of 1,823 persons (36% female) age 20 to 79 years who had screening for CAC by computed tomography, 279 had MetS, 150 had diabetes, and the remainder (n = 1,394) had neither condition. Metabolic syndrome was defined with >or=3 of the following: body mass index >or=30 kg/m(2); high-density lipoprotein cholesterol <40 mg/dl if male or <50 mg/dl if female; triglycerides >or=150 mg/dl; blood pressure >or=130/85 mm Hg or on treatment; or fasting glucose 110 to 125 mg/dl. The prevalence and odds of any and significant (>or=75th percentile) CAC among these groups and by number of MetS risk factors were determined. RESULTS: Those with neither MetS nor diabetes, MetS, or diabetes had a prevalence of CAC of 53.5%, 58.8%, and 75.3% (p < 0.001), respectively, among men and 37.6%, 50.8%, and 52.6% (p < 0.001), respectively, among women. Coronary artery calcium increased by the number (0 to 5) of MetS risk factors (from 34.0% to 58.3%) (p < 0.001). Forty-one percent of subjects with MetS had either a >20% 10-year risk of CHD or CAC >or=75th percentile for age and gender. Risk factor-adjusted odds for the presence of CAC were 1.40 (95% confidence interval [CI] 1.05 to 1.87) among those with MetS and 1.67 (95% CI 1.12 to 2.50) among those with diabetes, versus those with neither condition. CONCLUSIONS: Those with MetS or diabetes have an increased likelihood of CAC compared with those having neither condition.

Adult↗

PubMed2003

Determinants of risk and its temporal variation in patients with normal stress myocardial perfusion scans: what is the warranty period of a normal scan?

OBJECTIVES: The aim of this study was to determine the predictors of risk and the temporal characteristics of risk associated with normal myocardial perfusion single photon emission computed tomography (MPS). BACKGROUND: No empiric data exist regarding predictors of risk after normal MPS and their temporal characteristics. METHODS: Follow-up (mean: 665 +/- 200 days, 96% complete) of 7,376 consecutive patients with normal exercise or adenosine MPS identified 78 hard events (HE) (45 cardiac deaths, 33 non-fatal myocardial infarction; 1.1% cumulative HE rate, 0.6%/year). Cox proportional hazards analysis was used to identify predictors of HE. Parametric survival analysis was used to model predicted time to HE. RESULTS: The HE rates were greater in patients with versus without previous coronary artery disease (CAD). The Cox proportional hazards model identified pharmacologic stress, known CAD, diabetes mellitus (DM), male gender, and increasing age, with interactions between stress type and previous CAD (lower risk in patients without previous CAD undergoing exercise stress vs. all others) and between DM and gender (higher risk in DM females vs. all others) as the model most predictive of HE. The highest risk subgroups had a maximal event rate of 1.4% to 1.8%/year. Parametric survival models revealed that in patients without previous CAD the level of risk was uniform with time, but in patients with known CAD, risk increased with time (e.g., risk in the first year was less than in the second year, hence, a dynamic temporal component of risk was present). CONCLUSIONS: Multiple clinical factors add incremental prognostic value in patients with normal MPS, affecting their risk and its temporal pattern, and may alter the appropriate timing of repeat testing, hence establishing the existence of a "warranty" period for normal MPS studies.

Adenosine↗

PubMed2003

Adenosine myocardial perfusion single-photon emission computed tomography in women compared with men. Impact of diabetes mellitus on incremental prognostic value and effect on patient management.

OBJECTIVES: This study was designed to assess the incremental prognostic value of adenosine stress myocardial perfusion single-photon emission computed tomography (MPS) in women versus men, and to explore the prognostic impact of diabetes mellitus. BACKGROUND: Limited data are available regarding the incremental value of adenosine stress MPS for the prediction of cardiac death in women versus men and the impact of diabetes mellitus on post-adenosine MPS outcomes. Of 6,173 consecutive patients who underwent rest thallium-201/adenosine technetium-99m sestamibi MPS, 254 (4.1%) were lost to follow-up, and 586 with early revascularization < or = 60 days after MPS were censored, leaving 2,656 women and 2,677 men. RESULTS: Women had significantly smaller adenosine stress, rest, and reversible defects than men. During 27.0 +/- 8.8 month follow-up, cardiac death rates were lower in women than men (2.0%/year vs. 2.7%/year, respectively, p < 0.05). Before and after risk adjustment, cardiac death risk increased significantly in both men and women as a function of MPS results. Multivariable models revealed that MPS results provided incremental prognostic value over pre-scan data for the prediction of cardiac death in both genders. Also, while comparative unadjusted rates of early (< or =60 days post-test) coronary angiography (17% vs. 23%) and revascularization (8% vs. 12%) were significantly lower in women (p < 0.05), after adjusting for MPS, these rates were similar in men and women. Importantly, diabetic women had a significantly greater risk of cardiac death compared with other patients. Also, after risk adjustment, patients with insulin-dependent diabetes mellitus (IDDM) had higher risk of cardiac death for any MPS result than patients with non-insulin-dependent diabetes mellitus. CONCLUSION: The findings suggest that adenosine MPS has comparable incremental value for prediction of cardiac death in women and men and that MPS is appropriately influencing subsequent invasive management decisions in both genders. Diabetic women and patients with IDDM appear to have greater risk of cardiac death than other patients for any MPS result.

Adenosine↗

PubMed2003

Prognostic implications of combined prone and supine acquisitions in patients with equivocal or abnormal supine myocardial perfusion SPECT.

UNLABELLED: Although acquisition of (99m)Tc-sestamibi myocardial perfusion SPECT (MPS) with the patient in the prone position is commonly used to minimize attenuation artifacts, the impact of combined prone and supine imaging on the prognostic evaluation of coronary artery disease (CAD) has not been determined. The prognostic implications of MPS obtained in both prone and supine positions in patients with perfusion defects on supine MPS were evaluated. METHODS: We studied 3,834 patients who were monitored for 24.2 +/- 6.0 mo after rest (201)Tl/stress (99m)Tc-sestamibi MPS acquired during 1994-1995, when prone acquisition was performed only in patients with inferior wall perfusion defects that might represent attenuation or motion artifact. RESULTS: During follow-up, there were 132 hard events (cardiac death or myocardial infarction) and 375 total events (hard events or late myocardial revascularization). Overall, patients who underwent prone and supine acquisitions had similar characteristics to those who underwent supine-only imaging, with the exception of being more commonly male. In multivariable analysis, there were similar independent predictors for hard events and total events; the type of acquisition (prone and supine or supine-only) was not a significant predictor of either of these outcome events. After risk adjustment, the predicted event rates were nearly identical for patients undergoing prone and supine compared with supine-only studies. Both observed and predicted hard event rates of patients with normal prone and supine versus supine-only imaging were very low (observed, 0.7%/y and 0.5%/y, respectively; predicted, 1.5% over 24 mo for both). There was no reduction in the higher rates of events associated with abnormal scan results with the combination of prone and supine imaging. CONCLUSION: Patients with inferior wall defects on supine MPS that are not present on prone MPS have a low risk of subsequent cardiac events, similar to that of patients with normal supine-only studies.

Adenosine↗

PubMed2002

Value of stress myocardial perfusion single photon emission computed tomography in patients with normal resting electrocardiograms: an evaluation of incremental prognostic value and cost-effectiveness.

BACKGROUND: The incremental value and cost-effectiveness of stress single photon emission computed tomography (SPECT) is of unclear added value over clinical and exercise treadmill testing data in patients with normal resting ECGs, a patient subset known to be at relatively lower risk. METHODS AND RESULTS: We identified 3058 consecutive patients who underwent exercise dual isotope SPECT, who on follow-up (mean, 1.6+/-0.5 years; 3.6% lost to follow-up) were found to have 70 hard events (2.3% hard-event rate). Survival analysis used a Cox proportional hazards model, and cost-effectiveness was determined by the cost per hard event identified by strategies with versus without the use of SPECT. In this cohort, a normal study was associated with an exceedingly low hard-event rate (0.4% per year) that increased significantly as a function of the SPECT result. After adjusting for pre-SPECT information, exercise stress SPECT yielded incremental value for the prediction of hard events (chi2 52 to 85, P<0.001) and significantly stratified patients. In patients with intermediate to high likelihood of coronary artery disease after exercise treadmill testing, a cost-effectiveness ratio of $25 134 per hard event identified and a cost of $5417 per reclassification of patient risk were found. Subset analyses revealed similar prognostic, and cost results were present in men, women, and patients with and without prior histories of coronary artery disease. CONCLUSIONS: Stress SPECT yields incremental prognostic value and enhanced risk stratification in patients with normal resting ECGs in a cost-effective manner. These findings are opposite those of previous studies examining anatomic end points in this same population and thus, if confirmed, have significant implications for patient management.

Cohort Studies↗

PubMedDate not supplied

Diagnostic accuracy of gated Tc-99m sestamibi stress myocardial perfusion SPECT with combined supine and prone acquisitions to detect coronary artery disease in obese and nonobese patients.

BACKGROUND: The diagnostic value of gated myocardial perfusion single-photon emission computed tomography (MPS) with combined supine and prone acquisitions to detect coronary artery disease (CAD) in obese and nonobese patients has not been defined. METHODS AND RESULTS: We studied 1511 patients without prior myocardial infarction or coronary revascularization who either had coronary angiography within 3 months of MPS (n = 785) or had a low pretest likelihood of CAD (n = 726). All patients underwent rest thallium 201/gated exercise or adenosine stress technetium 99m sestamibi MPS in both the supine and prone positions. According to body mass index (BMI), patients were categorized as normal weight (BMI of 18.5-24.9 kg/m2), overweight (BMI of 25.0-29.9 kg/m2), or obese (BMI > or = 30.0 kg/m2). There were no significant differences in stress, fixed, or ischemic defects among patients in different weight categories. The sensitivity of MPS was 85%, 86%, and 89% for detecting patients with 50% or greater coronary stenosis and 89%, 91%, and 92% for detecting those with 70% or greater coronary stenosis in the normal-weight, overweight, and obese groups, respectively. Normalcy rates were nearly identical among the 3 weight groups (99%, 98%, and 99%, respectively). Multivariate logistic regression analysis further confirmed that BMI was a nonsignificant predictor for the detection of CAD. In a subset of 290 patients, automated quantitative MPS analysis confirmed that combined supine and prone MPS increased specificity (86%) in identifying CAD, without a significant reduction in sensitivity (83% for > or = 50% stenosis and 88% for > or = 70% stenosis). CONCLUSION: The findings of this study suggest that MPS performed with gating and combined supine and prone acquisitions without attenuation correction had a similar diagnostic accuracy for the detection of CAD in normal-weight, overweight, and obese patients.

Aged↗