Background: Previous studies have demonstrated the prognostic value of radionuclide ventriculography at rest and exercise in patients post myocardial infarction (MI). The number of studies in patients treated with modern reperfusion techniques, including thrombolysis or primary angioplasty, however, is limited.
Hypothesis: The aim of this study was to evaluate the prognostic significance of predischarge radionuclide ventriculography at rest and exercise in patients with acute MI treated with thrombolysis or primary angioplasty.
Methods: A total of 272 consecutive patients with acute MI who were randomized to thrombolysis or primary coronary angioplasty underwent predischarge resting and exercise radionuclide ventriculography. Left ventricular ejection fraction at rest, decrease in ejection fraction during exercise > 5 units below the resting value, angina pectoris, ST-segment depression, and exercise test ineligibility were related to subsequent cardiac events (cardiac death, nonfatal reinfarction) during follow-up.
Results: During a mean follow-up of 30 +/- 10 months, cardiac death occurred in 11 (4%) patients and nonfatal reinfarction in 14 (5%) patients. Resting left ventricular ejection fraction was the major risk factor for cardiac death. In patients with an ejection fraction < 40%, cardiac death occurred in 16% compared with 2% in those with an ejection fraction > or = 40% (p = 0.0004). In addition, cardiac death tended to be higher in patients ineligible than in those eligible for exercise testing (11 vs. 3%, p = 0.08). None of the other exercise variables (decrease in ejection fraction during exercise > 5 units below the resting value, angina pectoris or ST-segment depression) were predictive for cardiac death. When all exercise test variables in each patient were combined and expressed as a risk score, a low risk (n = 185) and a higher risk (n = 87) group of patients could be identified, with cardiac death occurring in 1 and 10%, respectively. As the predictive accuracy of a negative test was high, radionuclide ventriculography was of particular value in identifying patients at low risk for cardiac death. Radionuclide ventriculography was not able to predict recurrent nonfatal MI.
Conclusion: In patients with MI treated with thrombolysis or primary angioplasty, radionuclide ventriculography may be helpful in identifying patients at low risk for subsequent cardiac death. In this respect, left ventricular ejection fraction at rest was the major determinant. Variables reflecting residual myocardial ischemia were of limited prognostic value. Identification of a large number of patients at low risk allows selective use of medical resources during follow-up in this subgroup and has significant implications for the cost effectiveness of reperfusion therapies.