Rupture of the myocardium. Occurrence and risk factors.
The occurrence of myocardial rupture was studied in a well defined unselected population of patients with acute myocardial infarction, and the group of patients who died of rupture of the heart were compared with two control groups. Of a total of 3960 patients, 1746 (44%) fulfilled the diagnostic criteria for acute myocardial infarction. Rupture was defined solely on the basis of the presence of a pathological passage through part of the myocardium, either the free wall of the left ventricle or the septum, found at necropsy or during operation. Two controls were selected for each patient and matched for age and sex, one (control group A) with acute myocardial infarction having died in hospital but not of rupture (non-rupture cardiac death) and one (control group B) with acute myocardial infarction having survived the hospital stay. Necropsy was performed in 75% of all fatal cases with acute myocardial infarction. The total hospital mortality was 19%, the highest mortality being among women over 70 years (29%). Ruptures (n = 56) were found in 17% of the hospital deaths, or 3.2% of all cases of acute myocardial infarction. Women aged less than 70 had the highest incidence of rupture, 42% of deaths being due to rupture. The mean age for patients with rupture and controls was 70.5 years. The median time after admission to death was approximately 50 hours for patients and control group A. Thirty per cent of the patients with rupture occurred within 24 hours of the initial symptoms occurring. Angina and previous acute myocardial infarction were more common among control group A. Patients with rupture and control group B were mostly relatively free of previous cardiovascular or other diseases (chronic angina pectoris ( > 2 months) and previous myocardial infarction). Sustained hypertension during admission to the coronary care unit was more common in patients than in control group A. Hypotension and shock were more common among control group A. Most (79%) of the patients who subsequently ruptured did not receive any corticosteroids at all during the hospital stay. Severe heart failure and antiarrhythmic treatment were more uncommon among patients than among control group A. Patients with rupture received analgesics approximately three times a day throughout their stay. Control group B received analgesics mostly during the first 24 hours. Thus female patients, patients with first infarcts, and patients with sustained chest pain should be investigated for the possibility of rupture. As many as one third (32%) of ruptures may be subacute, and therefore time is available for diagnosis and surgery.