Aim of the study: In order to evaluate the incidence and clinical significance of myocardial ischemia during exercise testing (ExT) in patients (pts) with proven ischemic heart disease (Stable Effort Angina = SEA, Myocardial Infarction = MI, PTCA or CABG) 73 ergometric laboratories participated in a multicenter prospective study (SMISS) coordinated by the Italian Working Group on Cardiac Rehabilitation. Here we report the clinical and ergometric parameters.
Methods: Over a period of six months 4,389 consecutive pts were enrolled in the study after performing a maximal limited ExT (25 watts x 3') after drug withdrawal. All pts are followed at 6 and 12 months, at which time electrocardiogram, physical examination and clinical history were reassessed. A preliminary quality control of ECGraphic signal of ischemia was performed. Between the core center and the ergometric laboratories there was an 88% agreement (positive/negative ECG). 617 (14%) pts with angina (Group A), 2621 (59.7%) MI pts (Group B), 313 (7.2%) PTCA pts (Group C1), 838 (19.1%) patients with previous coronary bypass (Group C2) were studied.
Results: Interruption criteria were: maximal heart rate (11.7%), fatigue (66.6%), angina (10.9%), dispnea (2.3%), ST depression (13.9%), complex VPBs (2.2%), abnormal blood pressure (3.3%). In all pts the maximal work load was 100.3 +/- 31 W (lower in SEA pts). HR was 141 +/- 20/min at maximal work load (lower in SEA pts). The incidence of complex VPBs was 7.9% (higher in Mi and CABG pts). The results of ExT were: normal in 62% of all pts (21% in SEA pts), angina alone in 3.3% (7.6% in SEA pts and 1.8% in MI pts), symptomatic ischemia in 12.7% (40% in SEA pts, 9.3% in MI pts and 5.7% in CABG pts), silent ischemia in 22% (31.8% in SEA pts, 21.6 in MI pts and 16.6% in CABG pts). All differences were significant (p < 0.01).
Conclusions: In a low risk group of coronary patients the incidence of myocardial ischemia during ExT was 38%. Ischemia was silent in 58% of the patients.