[Effects of preceding stable or unstable angina on hospital morbidity-mortality of myocardial infarction. Results of a continuous series of 1,910 patients].

The aim of this study was to determine the effect of preceding unstable angina on the short-term prognosis of myocardial infarction based on early complications: cardiac failure, cardiac rupture, ventricular septal defect, sustained ventricular tachycardia ventricular fibrillation and hospital mortality. A continuous series of 1,910 patients admitted with 7 days of myocardial infarction was analysed retrospectively. The patients were divided into two groups according to their previous coronary history: Group A (myocardial infarction preceded by unstable angina) and Group B (myocardial infarction without preceding unstable angina). Group B was subdivided into Group B1 (myocardial infarction de novo) and Group B2 (myocardial infarction with previous stable angina). The results showed that patients with previous unstable angina (Group A) had a lower hospital mortality (7.9%) than those without (Group B) (13.3%) (p = 00017), fewer cardiac ruptures (1.1 versus 2.9%, p = 0.03) and less ventricular fibrillation (2.6 versus 4.5%, p = 0.053). Subgroups analysis showed that patients with de novo myocardial infarction (Group B1) had more sustained ventricular tachycardia than those with previous stable angina (Group B2) (5.3 versus 2.7%, p = 0.04). The authors conclude that pre-infarction unstable angina, possibly by ischaemic pre-conditioning, is an independent factor of a better prognosis in myocardial infarction.