Biomedical subjects

John D Friedman

Publications and source records attributed to John D Friedman.

43 records · Page 3Linked to original sources

PubMedDate not supplied

Rest perfusion defects in patients with no history of myocardial infarction predict the presence of a critical coronary artery stenosis.

BACKGROUND: The rest/stress sequence in myocardial perfusion single photon emission computed tomography (SPECT) (MPS) permits evaluation of rest images before stress testing, allowing the identification of unexpected perfusion defects (PDs). We sought to study the angiographic correlates of these resting PDs. METHODS AND RESULTS: This study comprised 139 consecutive patients with no history of myocardial infarction referred for MPS whose stress test was canceled because of the observation of unexpected resting PDs (rest group). Of these, 60 patients (43.2%) were referred for angiography after MPS (6.0 +/- 11.5 days). Angiographic referral rates and results were compared with those of a diagnostic population (n = 3565) who demonstrated stress-induced PDs (stress group) on rest/stress MPS. The mean age in the rest group was 73 +/- 12.5 years, and 73% were men. The frequency of referral for angiography was higher in the rest group (43.2% vs 19.8%, P <.0001). In addition, the rest group more frequently had significant coronary artery disease (CAD) (>/=70%) (95% vs 80%, P =.008) and critical CAD (>/=90%) (80% vs 66%, P =.038). CONCLUSION: The rest/stress sequence for MPS enables the identification of patients with unexpected resting PD, usually resulting from critical CAD, in whom unnecessary stress testing can be avoided.

Aged↗

PubMedDate not supplied

Prognostic validation of a 17-segment score derived from a 20-segment score for myocardial perfusion SPECT interpretation.

BACKGROUND: Recently, a 17-segment model of the left ventricle has been recommended as an optimally weighted approach for interpreting myocardial perfusion single photon emission computed tomography (SPECT). Methods to convert databases from previous 20- to new 17-segment data and criteria for abnormality for the 17-segment scores are needed. METHODS AND RESULTS: Initially, for derivation of the conversion algorithm, 65 patients were studied (algorithm population) (pilot group, n = 28; validation group, n = 37). Three conversion algorithms were derived: algorithm 1, which used mid, distal, and apical scores; algorithm 2, which used distal and apical scores alone; and algorithm 3, which used maximal scores of the distal septal, lateral, and apical segments in the 20-segment model for 3 corresponding segments of the 17-segment model. The prognosis population comprised 16,020 consecutive patients (mean age, 65 +/- 12 years; 41% women) who had exercise or vasodilator stress technetium 99m sestamibi myocardial perfusion SPECT and were followed up for 2.1 +/- 0.8 years. In this population, 17-segment scores were derived from 20-segment scores by use of algorithm 2, which demonstrated the best agreement with expert 17-segment reading in the algorithm population. The prognostic value of the 20- and 17-segment scores was compared by converting the respective summed scores into percent myocardium abnormal. Conversion algorithm 2 was found to be highly concordant with expert visual analysis by the 17-segment model (r = 0.982; kappa = 0.866) in the algorithm population. In the prognosis population, 456 cardiac deaths occurred during follow-up. When the conversion algorithm was applied, extent and severity of perfusion defects were nearly identical by 20- and derived 17-segment scores. The receiver operating characteristic curve areas by 20- and 17-segment perfusion scores were identical for predicting cardiac death (both 0.77 +/- 0.02, P = not significant). The optimal prognostic cutoff value for either 20- or derived 17-segment models was confirmed to be 5% myocardium abnormal, corresponding to a summed stress score greater than 3. Of note, the 17-segment model demonstrated a trend toward fewer mildly abnormal scans and more normal and severely abnormal scans. CONCLUSION: An algorithm for conversion of 20-segment perfusion scores to 17-segment scores has been developed that is highly concordant with expert visual analysis by the 17-segment model and provides nearly identical prognostic information. This conversion model may provide a mechanism for comparison of studies analyzed by the 17-segment system with previous studies analyzed by the 20-segment approach.

Aged↗

PubMedDate not supplied

Automated quantification of myocardial perfusion SPECT using simplified normal limits.

BACKGROUND: To simplify development of normal limits for myocardial perfusion SPECT (MPS), we implemented a quantification scheme in which normal limits are derived without visual scoring of abnormal scans or optimization of regional thresholds. METHODS AND RESULTS: Normal limits were derived from same-day TI-201 rest/Tc-99m-sestamibi stress scans of male (n = 40) and female (n = 40) low-likelihood patients. Defect extent, total perfusion deficit (TPD), and regional perfusion extents were derived by comparison to normal limits in polar-map coordinates. MPS scans from 256 consecutive patients without known coronary artery disease, who underwent coronary angiography, were analyzed. The new method of quantification (TPD) was compared with our previously developed quantification system and visual scoring. The receiver operator characteristic area under the curve for detection of 50% or greater stenoses by TPD (0.88 +/- 0.02) was higher than by visual scoring (0.83 +/- 0.03) ( P = .039) or standard quantification (0.82 +/- 0.03) ( P = .004). For detection of 70% or greater stenoses, it was higher for TPD (0.89 +/- 0.02) than for standard quantification (0.85 +/- 0.02) ( P = .014). Sensitivity and specificity were 93% and 79%, respectively, for TPD; 81% and 85%, respectively, for visual scoring; and 80% and 73%, respectively, for standard quantification. The use of stress mode-specific normal limits did not improve performance. CONCLUSION: Simplified quantification achieves performance better than or equivalent to visual scoring or quantification based on per-segment visual optimization of abnormality thresholds.

Aged↗

PubMedDate not supplied

Prognostic value of myocardial perfusion SPECT versus exercise electrocardiography in patients with ST-segment depression on resting electrocardiography.

BACKGROUND: The value of exercise-induced ST-segment depression for the prognostic evaluation of patients with 1 mm of ST depression or greater on the resting electrocardiogram is controversial. METHODS AND RESULTS: Patients who underwent exercise myocardial perfusion single photon emission computed tomography (MPS) and had resting ST depression of 1 mm or greater with a nondiagnostic exercise electrocardiographic response (n = 1122) were followed up for 3.4 +/- 2.3 years. Those with paced rhythm, pre-excitation, left bundle branch block, or myocardial revascularization within the first 60 days after MPS were excluded. Additional exercise-induced ST-segment depression was considered significant if > or = 2 mm MPS was scored semiquantitatively by use of a 20-segment model of the left ventricle; the percentage of myocardium involved with stress defects (% myo) was derived by normalizing to the maximal possible score of 80. Hard events were defined as nonfatal myocardial infarction or cardiac death. A Cox analysis was used to determine independent predictors of hard events among clinical, exercise, and nuclear variables. Hard event rates increased as a function of % myo for either patients with exercise-induced ST depression (1.4%/y for normal MPS vs 4.1%/y for % myo >10%, P < .03) or those without it (0.7%/y for normal MPS vs 3.0%/y for % myo >10%, P = .0001). Age, diabetes mellitus, shortness of breath as the presenting symptom, and % myo were independent predictors of hard events. Exercise-induced ST depression was predictive of hard events only when it was 3 mm or greater. The presence and extent of perfusion defects, reflected in the % myo, had incremental prognostic value over clinical variables and also over all degrees of exercise-induced ST depression. CONCLUSIONS: Although MPS effectively risk-stratifies patients with resting ST depression of 1 mm or greater, the prognostic value of exercise-induced ST depression is limited in these patients, with a small added risk when severe (> or = 3 mm).

Aged↗

PubMedDate not supplied

Diagnostic accuracy of rest/stress ECG-gated Rb-82 myocardial perfusion PET: comparison with ECG-gated Tc-99m sestamibi SPECT.

BACKGROUND: Although single photon emission computed tomography (SPECT) and positron emission tomography (PET) myocardial perfusion imaging (MPI) have evolved considerably over the last decade, there is no recent comparison of diagnostic performance. This study was designed to assess relative image quality, interpretive confidence, and diagnostic accuracy by use of contemporary technology and protocols. METHODS AND RESULTS: By consensus and without clinical information, 4 experienced nuclear cardiologists interpreted 112 SPECT technetium-99m sestamibi and 112 PET rubidium-82 MPI electrocardiography (ECG)-gated rest/pharmacologic stress studies in patient populations matched by gender, body mass index, and presence and extent of coronary disease. The patients were categorized as having a low likelihood for coronary artery disease (27 in each group) or had coronary angiography within 60 days. SPECT scans were acquired on a Cardio-60 system and PET scans on an ECAT ACCEL scanner. Image quality was excellent for 78% and 79% of rest and stress PET scans, respectively, versus 62% and 62% of respective SPECT scans (both p<.05). An equal percent of PET and SPECT gated images were rated excellent in quality. Interpretations were definitely normal or abnormal for 96% of PET scans versus 81% of SPECT scans (p=.001). Diagnostic accuracy was higher for PET for both stenosis severity thresholds of 70% (89% vs 79%, p=.03) and 50% (87% vs 71%, p=.003) and was higher in men and women, in obese and nonobese patients, and for correct identification of multivessel coronary artery disease. CONCLUSION: In a large population of matched pharmacologic stress patients, myocardial perfusion PET was superior to SPECT in image quality, interpretive certainty, and diagnostic accuracy.

Aged↗

PubMedDate not supplied

Risk stratification in patients with remote prior myocardial infarction using rest-stress myocardial perfusion SPECT: prognostic value and impact on referral to early catheterization.

BACKGROUND: Little is known about the prognostic value of myocardial perfusion single photon emission computed tomography (SPECT) in patients with remote prior myocardial infarction (MI). METHODS AND RESULTS: We identified 1413 consecutive patients with remote prior MI who underwent rest-stress myocardial perfusion SPECT. Semiquantitative visual analysis of 20 SPECT segments was used to define the summed stress, rest, and difference scores. The number of non-reversible segments was used as an index of infarct size. During follow-up (>or=1 year), 118 hard events occurred: 64 cardiac deaths (CDs) and 54 recurrent MIs. Annual CD and hard event rates increased significantly as a function of SPECT abnormality. For summed stress scores less than 4, 4 to 8, 9 to 13, and more than 13, the annual CD rates were 0.4%, 0.9%, 1.7%, and 3.5%, respectively (P =.002). Patients with small MI (<4 non-reversible segments) and no or mild ischemia (summed difference score or=4 non-reversible segments) had moderate to high annual CD rates (3.7%-6.6%) regardless of the extent of ischemia. Nuclear testing added incremental prognostic information to pre-scan information. Compared with a strategy in which all patients are referred to catheterization, a strategy that referred only those patients with a risk for CD of greater than 1% by myocardial perfusion SPECT resulted in a 41.6% cost savings. CONCLUSIONS: Myocardial perfusion SPECT adds incremental value to pre-scan information and is highly predictive and cost-efficient in the risk stratification of patients with remote prior MI. Patients with normal or mildly abnormal scan results or small MI in combination with absent or mild ischemia have a low risk for CD.

Adenosine↗

PubMedDate not supplied

Use of atropine in patients with submaximal heart rate during exercise myocardial perfusion SPECT.

BACKGROUND: Failure to reach 85% of maximal predicted heart rate (MPHR) during exercise may render a myocardial perfusion single photon emission computed tomography (MPS) study nondiagnostic for ischemia detection. Although commonly used to increase heart rate (HR) during dobutamine stress, the administration of atropine for patients failing to achieve 85% of MPHR during exercise performed for MPS is still infrequent. METHODS AND RESULTS: Patients undergoing dual-isotope MPS were considered candidates for the study when, during exercise treadmill testing, they had less than 85% of MPHR and were unable to continue because of fatigue, without an ischemic response. Forty-seven patients (aged 65.3 +/- 12.5 years, 78.7% men) received atropine (0.6-1.2 mg). Maximal HR achieved before and after atropine was 118.0 +/- 14.8 beats/min (76.3% +/- 6.2% of MPHR) and 146.4 +/- 12.6 beats/min (94.4% +/- 8.1% of MPHR), respectively (P < .001). Of patients, 44 (93.6%) reached at least 85% of MPHR after atropine and had diagnostic MPS studies. After atropine, arrhythmias occurred in 14 patients (29.8%) and other minor side effects in 1 (2.1%). CONCLUSIONS: Atropine allows patients initially failing to achieve 85% of MPHR during exercise to increase HR and have a diagnostic MPS study, without major complications. It may provide an alternative to pharmacologic stress for patients with a blunted HR response to exercise.

Aged↗