Prognostic significance of silent myocardial ischemia during exercise testing: Multicenter Silent Ischemia Study (SMISS).

Aim: the aim of the Multicenter Silent Ischemia Study (SMISS), co-ordinated by the Italian Working Group on Cardiac Rehabilitation, was to evaluate pr ospectively, the prognostic significance of silent myocardial ischemia duri ng exercise testing in patients with proven ischemic cardiac disease. Methods: over a period of six months 4389 consecutive patients performing a maximal symptom-limited exercise testing, after drug withdrawal, were enro lled in the 73 ergometric laboratories. All patients were followed up after 12 months, at which time electrocardiogram, examination and clinical histo ry were reassessed. Here we report the results of 1111 patients group with the recent myocardial infarction (inferior 3 months). The follow-up was com pleted in 1031 (93%) patients. Results: the results of exercise testing were normal in 666 (64.6%) patient s; angina alone in 33 (3.2%) patients; silent ischemia in 234 (22.7%) patie nts : symptomatic ischemia in 98 (9.5%) patients. In 270 patients (26.1%) n ew events occurred: angina (19.7%) : myocardial infarction (3.1% : PTCA (4% ); CABG (6%); cardiac death (1.4%). The total events were more common in th e patients with exercise induced angina (48.5%) and in those who had exerci se induced-symptomatic ischemia (48%), in respect of patients with silent i schemia (29.5%) and of those who had normal testing (20.7%) (p=0.0001). Myo cardial infarction rate was higher in patients with symptomatic Ischemia (7 .1%) that for those of all other groups (silent ischemia : 1.3%, angina : 3 %, normal 3.2%) (p=0.05). Moreover, the patients with symptomatic ischemia had higher incidence of CABG (p=0.0001). The mortality rate was low among all patients and did not show differences among the groups. Only among the 31 patients (3%) with blood pressure fall was mortality higher that in patients with a normal blood pressure increase . By multivariate logistic analysis the angina induced by exercise maintained its prognostic significance for all the events, but also other variables w ere significant: poor exercise tolerance and, between clinical variables an gina before myocardial infarction. Conclusion: the results showed, in patients who underwent to exercise testi ng after drug withdrawal, a low incidence of cardiac death and of myocardia l infarction on 12 month follow-up; the patients with induced-exercise symp tomatic schema had a greater risk for all cardiac events, except for death.