The prognostic value of submaximal exercise testing with radionuclide ventriculography before hospital discharge in patients with recent myocardial infarction.

Abstract

SUMMARY To test the hypothesis that patients at risk of future cardiac events can be identified by submaximal exercise testing with radionuclide ventriculography (RVG), 61 patients were studied a mean of 19 ± 1.0 days (± SEM) after acute myocardial infarction (MI). RVGs were used to measure left ventricular ejection fraction (LVEF), wall motion score (WMS), end-diastolic volume (EDV) and end-systolic volume (ESV), and the ratio of systolic blood pressure to ESV (P/V index) at rest and during submaximal exercise. Frank lead ECGs were analyzed for ST-segment change and arrhythmias. These patients were followed for a mean of 9.6 months (60 for 6 months or more and one for 3 months) to determine the incidence of cardiac death, recurrent MI, unstable or medically refractory angina, persistent congestive heart failure (CHF) or limiting angina; these problems were considered to be important cardiac events. At the 6-month follow-up, 37 patients had important complications: four patients died, five had MI, seven had unstable or medically refractory angina, 11 had persistent CHF and 10 had severe limiting angina.The sensitivity and specificity of RVG in predicting the important postinfarct complications listed above were 95% and 96% for failure to increase LVEF by at least 5 units, 95% and 96% for an increase in ESV of more than 5%, 97% and 88% for failure of the P/V Index to increase by more than 35%, and 81% and 88%, respectively, for a decrease in WMS. The sensitivity and specificity of the ECG in predicting important complications were 54% and 58%, respectively.The rest and submaximal exercise RVG variables, the ECG, a history of MI, the location of the infarction, Killip class III, age, sex, and maximal work load performed were analyzed statistically to determine the best predictors of prognosis. The change with exercise in LVEF, ESV and the P/V index were the most significant variables in predicting prognosis during the 6-month follow-up period. When patients with subsequent cardiac events were separated into those with death, recurrent MI and unstable or medically refractory angina as major cardiac events, and patients with persistent CHF and limiting angina as less important ("minor") cardiac events, only the peak submaximal exercise LVEF and history of MI were significant in distinguishing these groups. In patients without important cardiac events during the 3-and 6-month follow-up, 70% and 88%, respectively, had no abnormality in the responses of LVEF, ESV, or P/V index to submaximal exercise. These results suggest that submaximal exercise testing with RVG is a highly sensitive means of classifying patients at the time of hospital discharge after MI according to the likelihood of having cardiac events during the ensuing 6 months. THE PROGNOSIS of patients after myocardial infarction (MI) has been studied extensively. Several clinical criteria and diagnostic procedures have been used to identify patients at risk for subsequent complications;'4 however, the sensitivity and specificity of these tests vary widely.7 ...

Prognostic utility of the exercise thallium-201 test in ambulatory patients with chest pain: comparison with cardiac catheterization.

“…38 nation for why thallium-201 variables are more predictive of future cardiac events in comparison to the exercise stress test alone may be related to the better detection of multivessel ischemia than can be accomplished with exercise ECG. Our findings are also consistent with the reported studies that have used exercise radionuclide angiography for risk stratification and prognostication.8, 9, [42][43][44][45] Some differences are apparent between results of the present study an those reported by Kaul et al27 Whereas in our study the number of diseased vessels was the most significant single predictor of future events, a quantitative estimation of the lung/heart ratio of thallium-201 was the most important predictor of events in the latter study, making the exercise thallium-201 stress test a more powerful predictor of future events than cardiac catheterization.27 Certain important differences in the patient populations in these studies might in part explain the seeming disparities. For example, in the present study, 41 of the 89 (46%) patients with events died during follow-up compared with 20 of 91 (22%) in the Massachusetts General Hospital study, suggesting that a higher-risk population was followed medically in the present study, perhaps because during the period that patients were enrolled (between 1978 and 1981), CABG was not being offered as frequently as in later years to patients with extensive multivessel disease and poor left ventricular function or those with multivessel disease and relatively poor distal runoff.…”

Comparison of immediate invasive, delayed invasive, and conservative strategies after tissue-type plasminogen activator. Results of the Thrombolysis in Myocardial Infarction (TIMI) Phase II-A trial.

“…Exercise testing suggested that the conservative strategy group was still more likely to have evidence of residual ischemic myocardium shortly before hospital discharge, a finding that generally predicts poorer 1-year survival. 19 These exercise test findings corresponded to quantitative coronary arteriography at the time of hospital discharge, which confirmed that the infarct-related arteries in this subgroup of patients had more severe residual stenoses than those patients in the invasive strategy subgroups.…”

Prediction of cardiac events after uncomplicated myocardial infarction: a prospective study comparing predischarge exercise thallium-201 scintigraphy and coronary angiography.

“…When our population is compared with others with similar residual left ventricular function, our results are similar. 33 Clinical implications. Our data indicate that two distinct groups of patients recovering from an uncomplicated acute myocardial infarction can be identified by quantitative 20T1 scintigraphy in conjunction with heart rate-limited exercise stress before hospital discharge.…”