Accurate detection of triple vessel disease in patients with exercise induced ST segment depression after infarction

Predischarge maximal exercise test identifies risk for cardiac death in patients with acute myocardial infarction

A maximal exercise test was performed in 54 patients with acute myocardial infarction (AMI) before discharge and in 49 age-matched control subjects. The long-term prognosis was assessed after an average follow-up of 7.6 years in AMI patients and 5.8 years in control subjects. The maximal work capacity and systolic blood pressure increase in AMI patients was 59% that of control subjects (p less than 0.001). Seventeen AMI patients had significant ST-segment shifts, 13 with ST depression and 4 with ST elevation. In AMI patients experiencing a cardiac death during follow-up the maximal work capacity and systolic blood pressure increase were significantly lower than in survivors and those who died from noncardiac reasons (p less than 0.01; p less than 0.05), with no difference between these groups in the number of patients with ST-segment shifts. The average maximal work capacity of control subjects was 143 watts. A maximal work capacity half this (less than or equal to 72 watts) predicted long-term mortality in AMI patients (p less than 0.001). In addition a low increase in systolic blood pressure (less than 30 mm Hg) also predicted long-term mortality (p less than 0.005), whereas ST shifts were of no significant value. In this study maximal work capacity turned out to be the best single exercise variable for identifying groups of AMI patients with very low and relative high risk of cardiac death. When all 3 exercise variables were combined, the predischarge maximal exercise test was of great value in identifying AMI patients at low risk for cardiac death (predictive value of a negative test: 95%).

Does beta adrenergic blockade influence the prognostic implications of post-myocardial infarction exercise testing?

The influence of beta blockade on the ability of ST depression, during pre-discharge exercise testing, to predict coronary anatomy and subsequent complications was studied in 300 consecutive post-infarct patients, 125 of whom underwent cardiac catheterisation. At the time of exercise 62 patients were taking a beta blocker. The exercise test had a higher sensitivity in predicting multivessel disease in patients who were not taking beta blockers than in patients who were (95% v 76%). beta Blockade did not, however, influence the ability of the test to identify patients at risk of subsequent cardiac events (sensitivity 84% and 85% respectively). These results suggest that it is not necessary to stop treatment with beta blockers before predischarge exercise testing of patients who have had an acute myocardial infarction.

Prospective evaluation of clinical assessment, exercise testing and signal-averaged electrocardiogram in predicting outcome after acute myocardial infarction

The relative value of exercise testing, late potentials and simple clinical assessment in predicting ischemic and arrhythmic events during follow-up after acute myocardial infarction (AMI) was investigated prospectively in a population of 176 consecutive patients surviving to 7 days after AMI. During 15 +/- 9 (range 3 to 24) months of follow-up, there were 23 ischemic events (2 fatal reinfarctions, 6 nonfatal reinfarctions and 16 patients who underwent coronary artery bypass grafting, 1 after reinfarction) and 11 arrhythmic events (7 symptomatic ventricular tachycardias and 4 sudden cardiac deaths). Stepwise multiple regression analysis showed that out of 11 variables, including exercise testing, late potentials and clinical data, exercise testing was the only independent variable predicting the occurrence of ischemic events (p less than 0.05 not including coronary artery bypass grafting and p less than 0.002 including it). Arrhythmic events were predicted, in order of importance, by Killip class (p less than 0.05), late potentials (p less than 0.005), previous AMI (p less than 0.009), occurrence of in-hospital complications (p less than 0.005) and non-Q-wave AMI (p less than 0.02). The presence of late potentials provided independent prognostic information from the Killip class and the result of exercise testing in predicting both arrhythmic and ischemic events. Exercise testing, late potentials and clinical assessment provide complementary prognostic information in postinfarction patients.

Relative power of clinical, exercise test, and angiographic variables in predicting clinical outcome after myocardial infarction: the Newham and Tower Hamlets study

The interrelations of clinical, exercise test, and angiographic variables and their relative values in predicting specific clinical outcomes after myocardial infarction have not been fully established. Of 302 consecutive stable survivors of infarction, 262 performed a predischarge submaximal exercise test. In the first year after infarction patients with a "positive" exercise test were 13 times more likely to die, 2.8 times more likely to have an ischaemic event, and 2.3 times more likely to develop left ventricular failure than patients with negative tests. Patients with positive exercise tests underwent cardiac catheterization. Features of the history, 12 lead electrocardiogram, in-hospital clinical course, exercise test, and left ventricular and coronary angiograms that predicted these clinical end points were identified by univariate analysis. Then multivariable analysis was used to assess the relative powers of all variables in predicting end points. Certain features of the exercise test remained independent predictors of future ischaemic events and the development of overt left ventricular failure, but clinical and angiographic variables were more powerful predictors of mortality. Because the exercise test is also used to select patients for angiography, however, the results of this study strongly support the use of early submaximal exercise testing after infarction.

The dobutamine stress test as an alternative to exercise testing after acute myocardial infarction

Three weeks after myocardial infarction in 50 patients the effect of the infusion of a graded dose of dobutamine was compared with that of symptom limited treadmill exercise testing. The following variables were measured: blood pressure, heart rate, ST segment changes, Doppler aortic blood flow, and cross sectional echocardiographic dimensions. The heart rate and double product increased more during exercise than during dobutamine infusion, while maximum acceleration in the ascending aorta increased more during dobutamine infusion than during exercise. Significant ST depression was recorded in 22 patients during exercise and in 24 during dobutamine infusion; the concordance between the two tests was 88%. In all cases in which ST segment depression occurred in both tests the site of ST depression was the same. Dobutamine stress testing is an alternative to exercise testing in patients after myocardial infarction.