Purpose: To compare the predictive accuracy for future ischemic events of heart rate limited treadmill exercise test (HET) and coronary angiography (CA) applied to survivors of an uncomplicated myocardial infarction.
Methods: 142 consecutive patients (55 +/- 11 years, 80% males), presenting a non complicated acute myocardial infarction (AMI) were included. HET was performed 10 +/- 3 days after AMI, and CA during hospital stay or within 4-6 weeks. HET positivity criteria were: 1) horizontal or down-sloping ST segment displacement > or = 1 mm; 2) angina; 3) arterial pressure drop during exercise; 4) low workload (< 6 METS); 5) complex ventricular arrhythmia. At CA lesions causing > or = 50% of luminal reduction were considered significant. HET and CA results were correlated to ischemic events occurring during the follow-up (unstable angina in 20%, cardiac death 6%, and reinfarction 6%).
Results: HET was positive in 69 (49%) patients, exhibiting a positive predictive value for ischemic events (PV+) of 26% and a negative predictive value (PV-) of 77%. The mean event-free time was 43 +/- 3 months for positive HET and 46 +/- 3 months for a negative one (p = 0.48). CA showed 0-1 vessel involvement in 93 (66%) patients and > or = 2 vessels in 49 (34%) patients. The presence of multivascular disease at CA presented a PV+ of 37% and PV- of 82%; the mean event-free time was 37 +/- 4 months for patients with multivascular involvement and 48 +/- 2 months for patients without this pattern (p = 0.007).
Conclusion: The predictive accuracy of HET for future ischemic events in the thrombolytic era is markedly reduced. This population of AMI survivors presents an overall good prognosis that seems to justify the poor predictive accuracy of this test.