Study objectives: Clinical characterization and aspects of subsidiary clinical tests in a group of patients with myocardial infarction with no visible angiographic atherosclerotic stenosis. Etiologic identification, therapeutic approach and prognostic assessment of non atherosclerotic myocardial infarction.
Patients: We studied patients admitted with myocardial infarction to coronary care unit over a 4 year period and in whom cardiac catheterism did not show atherosclerotic coronary stenosis (17 patients).
Methodology: Retrospective study; Assessment of clinical characteristics, exercise test parameters, echocardiogram, hemodynamics, heart rate variability (HRV) and signal-averaged electrocardiogram (ECG) of this group of patients; Maximal follow-up of 44 months and minimal of 3 months (average: 19.9 +/- 12.7 months) for the occurrence of ischemic cardiac events (recurrent angina, reinfarction or sudden death).
Results: Non atherosclerotic coronary infarction was an unusual situation (2% of the totality of the infarction hospitalized during those 4 years--795 cases), occurring mainly among young men, with few vascular risk factors (except smoking), as small infarctions, without a preferential localization and with good evolution in the acute phase (Killip I). In the predischarge exercise test there was no residual ischemia and functional capacity was generally good. In the majority of cases left ventricular systolic function was preserved (82% of the cases). With cardiac catheterism, we observed two cases of "bridging" and four cases of slow contrast progression. In arrhythmic risk stratification with 24 hours ECG, HRV and high resolution ECG, we observed no adverse prognostic markers in the majority of the cases. The clinical observation of the patients and the tests permitted us to establish probable hypotheses for the etiological diagnoses in 10 of the cases (left main anterior descending artery "bridging"--2 cases; slow contrast progression in the coronary vessels--4 cases, severe aortic stenosis--1 case; left valvular mechanic prosthesis--1 case: probable coronary thrombosis with complete reperfusion after thrombolytic therapy--2 cases). The therapeutic approach in the acute phase was the same as that of atherosclerotic infarctions. Secondary prevention was individualized and according to each case etiology, maintaining the antiplatelet agents. In the follow-up there was unstable angina in 3 patients. There were no cases of reinfarction or sudden death.
Conclusions: This study allowed the characterization of the group of non atherosclerotic myocardial infarction as a group of young men with few vascular risk factors, with small infarctions and good prognosis, without adverse arrhythmic risk markers. It also allowed to identify the probable infarction etiology in 10 patients and the secondary individual prevention for each situation. We noted a good prognosis of this situation at two years.