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Biomedical subjects

N Zafrir

Publications and source records attributed to N Zafrir.

At least 19 recordsLinked to original sources
PubMed2001

The utility and potential cost-effectiveness of stress myocardial perfusion thallium SPECT imaging in hospitalized patients with chest pain and normal or non-diagnostic electrocardiogram.

BACKGROUND: The evaluation of hospitalized patients with chest pain and non-diagnostic electrocardiogram is problematic and the optimal cost-effective strategy for their management controversial. OBJECTIVES: To determine the utility of myocardial perfusion imaging with thallium-201 for predicting outcome of hospitalized patients with chest pain and a normal or non-diagnostic ECG. METHODS: On pain cessation, 109 hospitalized patients, age 61 +/- 14 years (mean +/- SD), with chest pain and non-diagnostic ECG underwent stress myocardial perfusion SPECT imaging with thallium-201. Costs related to their management were calculated. The occurrence of non-fatal myocardial infarction or cardiac death was recorded at 12 +/- 5 months follow-up. RESULTS: A normal SPECT was found in 84 patients (77%). During one year follow-up, only 1 (1.2%) compared to 7 (28%) cardiac events (6 myocardial infarctions, 1 cardiac death) occurred in patients with normal versus abnormal scans respectively (P < 0.0001). Negative predictive value and accuracy of the method were 99% and 83% respectively. Multivariate regression analysis identified an abnormal SPECT as the only independent predictor of adverse cardiac event (P = 0.0016). Total cost from admission until discharge was 11,193 vs. 31,079 shekels (P < 0.0001) for normal and abnormal scan. Considering its high negative predictive value, shortening the hospital stay from admission until scan performance to 2 days would result in considerably reduced management costs (from NIS 11,193 to 7,243) per patient. CONCLUSION: Stress SPECT applied to hospitalized patients with chest pain and a normal or non-diagnostic ECG is safe, highly accurate and potentially cost effective in distinguishing between low and high risk patients.

Aged↗
PubMed2000

Relation between evolutionary ST segment and T-wave direction and electrocardiographic prediction of mycardial infarct size and left ventricular function among patients with anterior wall Q-wave acute myocardial infarction who received reperfusion therapy.

In the prethrombolytic era it was found that infarct size and left ventricular ejection fraction could be predicted using the Selvester QRS score. We evaluated whether infarct size and left ventricular ejection fraction could be predicted by the predischarge QRS score in patients who had received reperfusion therapy and whether considering the configuration of the ST segments and T waves would increase the accuracy of these predictions. We evaluated 51 patients with first anterior wall myocardial infarction who had received reperfusion therapy and predischarge resting technetium-99m-sestamibi scan. The electrocardiograms recorded on the same day of the scan were analyzed for the QRS score and were divided into 3 groups: A, isoelectric ST and negative T waves; B, ST elevation (> or =0.1 mV) and negative T waves; and C, ST elevation (> or =0.1 mV) and positive T waves. Groups A, B, and C included 12, 23, and 16 patients, respectively. The myocardial perfusion defect extent increased from groups A to C (median 21%, 37%, and 43.5% in groups A, B, and C, respectively; p = 0.023). Similarly, left ventricular ejection fraction decreased (44%, 38%, and 34%, respectively; p = 0.042) from groups A to C. Overall, the correlation between the QRS score and the myocardial perfusion defect extent (rho 0.249; p = 0.08) and ejection fraction (rho -0.229; p = 0.11) was poor. A statistically significant correlation between myocardial perfusion defect size and QRS score was found only in group A (rho 0.599, p = 0.04). Among patients with anterior myocardial infarction who received reperfusion therapy, the predischarge QRS score was predictive of infarct size only in those in whom ST elevation resolved completely. In patients with residual ST elevation there was no correlation between QRS score and infarct size.

Angioplasty, Balloon, Coronary↗
PubMed2000

Persistent ST segment depression in precordial leads V5-V6 after Q-wave anterior wall myocardial infarction is associated with restrictive physiology of the left ventricle.

OBJECTIVES: To examine the relationship between the persistence of ST segment depression in leads V5-V6 after Q-wave anterior wall myocardial infarction (MI) and the filling pattern of the left ventricle (LV). BACKGROUND: Precordial ST segment depression predominantly in leads V5-V6 is associated with increased in-hospital morbidity and mortality after acute myocardial ischemia, perhaps due to reduced diastolic distensibility of the LV. METHODS: We prospectively studied 19 patients after Q-wave anterior wall MI (>6 months). All patients underwent 12-lead ECG recording, symptom-limited treadmill exercise testing with single photon emission computed tomography thallium-201 imaging, transthoracic Doppler echocardiography, cardiac catheterization and measurement of circulating atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) levels. Patients were classified based on the presence of ST segment depression in leads V5-V6: Group I = ST segment depression <0.1 mV (n = 10); Group II = ST segment depression > or =0.1 mV (n = 9). RESULTS: Patients in Group II had greater LV end diastolic pressures (32.4 +/- 6.5 mm Hg vs. 14.8 +/- 6.1 mm Hg; p = 0.0001), higher plasma ANP (44.4 +/- 47.1 pg/ml vs. 10.7 +/- 14 pg/ml; p = 0.04) and BNP levels (89.4 +/- 62.7 pg/ml vs. 23.6 +/- 33.1 pg/ml; p = 0.01), greater left atrium area (20.6 +/- 3.1 cm2 vs. 17.8 +/- 2.4 cm2; p = 0.05), lower peak atrial (A), higher early (E) mitral inflow velocities, a higher E/A ratio and a lower deceleration time (167 +/- 44 ms vs. 220 +/- 40 ms; p = 0.05). Lung thallium uptake during exercise was more common in Group II (78% vs. 10%, p = 0.04). CONCLUSIONS: Persistent ST segment depression in leads V5-V6 in survivors of Q-wave anterior wall MI is associated with increased LV filling pressure and a restrictive LV filling pattern.

Atrial Natriuretic Factor↗
PubMed1999

Usefulness of dobutamine radionuclide ventriculography for prediction of left ventricular function improvement after coronary artery bypass grafting for ischemic cardiomyopathy.

Ventricular function may improve after coronary artery bypass grafting (CABG) in patients with ischemic cardiomyopathy depending on the amount of contractile myocardial reserve. Based on the studies using dobutamine echocardiography to predict regional wall improvement after revascularization, we investigated the benefit of low-dose dobutamine radionuclide ventriculography for assessing functional contractile reserve in this population. The study group included 56 patients with ischemic cardiomyopathy (mean left ventricular [LV] ejection fraction [EF] of 23 +/- 5%) and multivessel disease, who were referred for viability assessment. All underwent radionuclide ventriculography before and during infusion of 5 and 10 microg/kg/min of dobutamine. An increase in global LVEF from rest to dobutamine was calculated, and 10% was considered the cutoff value to predict ventricular improvement after CABG. Of the 35 patients who underwent CABG 1 month later, 29 were available for repeated radionuclide ventriculography after 12 +/- 5 months. Of these, 15 showed improvement (delta LVEF > or = 5%, mean 10 +/- 5%) and 14 did not (delta LVEF < 5%, mean -1 +/- 3%). The increase in EF with dobutamine had the highest univariate predictive value of all parameters evaluated. The sensitivity, specificity, and positive and negative predictive values of dobutamine radionuclide ventriculography were 67%, 93%, 91%, and 72%, respectively. We conclude that dobutamine radionuclide ventriculography is a useful method to assess contractile reserve and predict ventricular functional improvement after CABG in patients with ischemic cardiomyopathy.

Adrenergic beta-Agonists↗
PubMed1999

Relation between aerobic capacity and extent of myocardial ischemia in patients with normal cardiac function.

BACKGROUND: The relation between aerobic capacity and extent of exercise-induced myocardial ischemia has not been investigated. Fifty patients with coronary artery disease (>/=50% stenosis) without myocardial infarction underwent cardiopulmonary exercise testing followed by quantitative thallium perfusion imaging. Results were compared with those of age- and sex-matched healthy controls with a low likelihood of coronary artery disease. Patients with Q-wave infarction, pulmonary disease, and peripheral vascular disease were excluded. Cardiopulmonary exercise testing and thallium perfusion imaging parameters were correlated for extent of global ischemia, occurrence of increased pulmonary thallium uptake, and transient ventricular dilatation during exercise. RESULTS: Patients with global ischemia <20% (group 1, n = 25) had normal cardiopulmonary exercise testing results, similar to the control group, except for workload and maximal predicted heart rate, which were reduced. However, patients with ischemia >/=20% (group 2, n = 25) had poor cardiopulmonary exercise testing results compared with the controls. The ventilatory anaerobic threshold showed the most significant decrease of all cardiopulmonary exercise testing parameters (48% +/- 6% vs 57% +/- 6%, P <.0001), and it was the only parameter to correlate with extent of ischemia (r = -0.5; P <.003) as well as frequency of increased pulmonary uptake and transient ventricular dilatation (r = -0.33, P =.03). CONCLUSIONS: Ventilatory anaerobic threshold is significantly related to extent of myocardial ischemia and signs of heart failure during exercise. However, patients with mild to moderate exercise-induced ischemia may have normal cardiopulmonary exercise testing performance.

Aged↗
PubMed1998

Thallium reinjection versus standard stress/delay redistribution imaging for prediction of cardiac events.

OBJECTIVES: The purpose of this study was to compare thallium reinjection with standard stress/delay redistribution for the prediction of cardiac events. BACKGROUND: Although thallium reinjection enhances the detection of viable myocardium, its contribution to prognosis over stress/delay redistribution in a general referral population has not been clearly evaluated. METHODS: This retrospective analysis included 366 consecutive patients with coronary artery disease who underwent stress/delay redistribution imaging and thallium reinjection scintigraphy, with a mean follow-up of 33+/-12 months. RESULTS: Cardiac events occurred in 48 patients (40 deaths, 8 myocardial infarctions). Of the 366 original patients, 159 demonstrated ischemia by stress/delay redistribution, 107 showed ischemia by reinjection only, and 100 showed infarction only. Cardiac events occurred in 20 patients (12.6%) with stress/delay redistribution, 13 patients (12%) with ischemia detected by thallium reinjection only and 15 patients (15%) with infarction only. The size of the reversible thallium defect by either stress/delay redistribution imaging or reinjection scintigraphy did not predict cardiac events. Independent predictors of cardiac events included left ventricular cavity size, the size of the abnormal perfusion defect and patient age. CONCLUSIONS: Thallium reinjection does not contribute independent prognostic utility for cardiac events when compared with stress/delay redistribution. Left ventricular dilation and the size of the post-stress defect were predictors of cardiac events.

Aged↗
PubMed1998

Assessment of functional results after percutaneous transluminal coronary angioplasty by cardiopulmonary exercise test.

Twenty-nine patients with documented coronary artery disease underwent cardiopulmonary exercise tests before and following a percutaneous transluminal coronary angioplasty (PTCA). The patients medication regimen and exercise protocols remained the same in both cases. Following PTCA, significant improvement (p < 0.001-0.0001) was noted in oxygen consumption (1,526.8 +/- 470.0 vs. 1,686.2 +/- 390 ml/min), oxygen pulse (12.40 +/- 2.73 vs. 13.44 +/- 2.9 ml/beat), oxygen pulse score (7.62 +/- 1.29 vs. 8.85 +/- 1.26 points) and in the ventilatory anaerobic threshold (993.1 +/- 177.6 vs. 1,089.8 +/- 150.9 ml/min) but not (p > 0.05) in maximal heart rate (128.7 +/- 16.9 vs. 132.0 +/- 17.2 beats/min). Thus, a cardiopulmonary exercise test is an effective method to assess functional results following PTCA.

Adult↗
PubMed1997

Predictive value of dobutamine radionuclide ventriculography in detection of functional improvement after acute anterior wall infarction and thrombolytic therapy.

BACKGROUND: Prolonged postischemic ventricular dysfunction (stunned myocardium) may prevent the assessment of myocardial salvage early after thrombolysis. Dobutamine in conjunction with radionuclide ventriculography has been proposed for the early assessment of myocardial viability and prediction of functional recovery. HYPOTHESIS: This study was designed to investigate the effects of low-dose dobutamine infusion on early global and regional function of reperfused myocardium after acute anterior wall myocardial infarction (MI). In particular, our purpose was to examine whether this response can predict late recovery of left ventricular function and correlate with the reperfused status (patency of infarct-related artery). METHODS: In all, 29 consecutive patients with first uncomplicated anterior wall MI, and who had received thrombolytic therapy, underwent radionuclide ventriculography at rest and 2 min after each dose increment of dobutamine infusion (5-15 micrograms/kg/min) on the third day after the infarction, at discharge, and at 3 months' follow-up. Global and regional ejection fraction were calculated at each stage. Four patients with complications were dropped from the study. A significant response to dobutamine was defined as an increase of at least > or = 7% in global or regional ejection fraction at the infarct zones. RESULTS: Of the 25 patients, 18 (72%) fulfilled these criteria. Of these, 10 patients (56%) had a significant improvement in global or regional ejection fraction at discharge and 13 patients (72%) at 3-month follow-up. The overall sensitivity of the dobutamine test in predicting left ventricular improvement was 100% at discharge and 93% at 3-month follow-up. However, the positive and negative predictive values were 56 and 100% at discharge and 72 and 86%, respectively, at 3-month follow-up. CONCLUSION: Low-dose dobutamine radionuclide ventriculography is a safe and useful test for assessing myocardial viability and may predict late functional improvement in patients with anterior wall MI.

Dobutamine↗
PubMed1996

Increased adhesiveness of peripheral blood leukocytes corresponds to the appearance of expansion following anterior wall myocardial infarction.

The appearance of increased leukocyte adhesiveness/aggregation as an inflammatory marker in the peripheral blood of patients with anterior wall myocardial infarction was monitored. Of the 26 patients included in the study, 7 had infarct expansion as shown by an enlargement of left ventricular end-diastolic volume. The percent of aggregated leukocytes in the peripheral blood of patients with expansion (29.7 +/- 15.5%) was significantly higher (p = 0.01) than that obtained from patients with no expansion (18.5 +/- 6.8%). The lack of significant differences in peak creatine kinase concentrations between patients with and without expansion suggests that infarct size is not necessarily the main determinant for the appearance of expansion; an increased inflammatory reaction could be a contributory factor.

Cell Adhesion↗
PubMed1995

Effect of dipyridamole on myocardial perfusion and function using technetium-99m MIBI.

Myocardial perfusion imaging with dipyridamole is an accepted method for diagnosing coronary artery disease. However, the simultaneous effect of dipyridamole on perfusion and function in the detection of coronary artery disease has not been studied extensively. The aim of this study was to investigate this effect using technetium-99m methoxy isobutyl isonitrile (Tc-MIBI) imaging. Twenty-eight patients with proven coronary artery disease participated in a 2-day protocol (rest and then 0.56 mg/kg dipyridamole i.v.) using Tc-MIBI for first-pass radionuclide ventriculography followed by SPECT imaging. Fifteen patients (54%) demonstrated a decrease in left ventricular ejection fraction from rest to dipyridamole and/or wall motion abnormality, while 21 patients (75%) showed abnormal perfusion by dipyridamole MIBI SPECT imaging. Concordance between perfusion and function was 65%. Correlation for one-, two- and three-vessel disease (coronary angiography) to perfusion versus function were: 54% vs. 38%, 80% vs. 60% and 80% vs. 80%, respectively. Left ventricular dysfunction using dipyridamole was noted in patients with multivessel disease, and with multi-reversible perfusion filling defects. We conclude that dipyridamole in combination with Tc-MIBI for assessment of perfusion and function serves as a valuable tool to identify patients with multivessel disease and a high amount of myocardium at risk.

Aged↗
PubMed1995

The effect of lovastatin on early restenosis.

The effect of lovastatin given before percutaneous coronary angioplasty (PTCA) on early restenosis was investigated in men with mild to moderate hypercholesterolemia. Thirty-four hypercholesterolemic patients (serum LDL cholesterol 130-200 mg/dL) undergoing their first PTCA completed a 6-month prospective, double-blind, placebo-controlled trial. Eighteen received lovastatin 20 mg/day (Lo group) and 16 placebo (P1 group), beginning 10 to 21 days before PTCA. All underwent a thallium-201 quantitative exercise test 5 to 7 days after PTCA. Endpoints for restenosis were either 50% narrowing of the dilated artery on coronary angiography, performed in symptomatic patients or, in asymptomatic patients, the appearance of newly developed reversible filling defects in the vascular territory of the dilated artery on a second thallium scan done 6 months after PTCA. The hypocholesterolemic change observed in the Lo group was not accompanied by a reduction in early restenosis risk. The authors conclude that effective hypocholesterolemic therapy before PTCA does not affect early restenosis rate in men with mild to moderate hypercholesterolemia.

Adult↗
PubMed1994

Dipyridamole first-pass radionuclide ventriculography: prediction of future cardiac events.

Dipyridamole thallium myocardial perfusion imaging is a useful alternative to stress testing in the diagnostic and prognostic assessment of patients with coronary artery disease. The diagnostic use of dipyridamole radionuclide ventriculography is much more controversial, but no long-term prognostic studies have been reported. Imaging results of 159 consecutive patients who were referred for dipyridamole first-pass radionuclide ventriculography were correlated with subsequent cardiac events over a mean follow-up period of 11 months. An abnormal response to dipyridamole infusion (any reduction in wall motion or absolute decrease in global left ventricular ejection fraction of > or = 5 ejection fraction units) was associated with an increased incidence of nonfatal myocardial infarction (4.5% vs 0%, p < 0.05) and cardiac-related death (9% vs 1%, p < 0.001). The sensitivity, specificity, and negative predictive value of dipyridamole first-pass radionuclide ventriculography in predicting future cardiac events were 86%, 71%, and 98%, respectively, with a relative risk of 15 (confidence interval 12.06 to 18.1). In conclusion, dipyridamole first-pass radionuclide ventriculography demonstrated significant prognostic value in a large unselected patient population. This technique may provide a widely applicable and useful alternative to dipyridamole thallium perfusion imaging in the assessment of cardiac risk in patients with coronary artery disease.

Aged↗