924-116 Activity at the Onset of Symptoms and Outcome of Acute Myocardial Infarction

Recent studies have confirmed that vigorous exercise can trigger myocardial infarction (MI), but it is not clear whether outcome is influenced by the activity at the onset of symptoms. This study compares clinical features and in hospital mortality for patients (pts) whose symptoms of MI began at rest, in bed, or during or after exercise.A standard questionnaire which included information on activity at the onset of symptoms, risk factors and outcome was completed following admission for all pts admitted to the CCU from 1975 to 1993. The study population is 2468 pts with a first MI. At the onset of symptoms 40% of pts were resting, 33% were in bed and 27% were or had been exercising (>4 METS) during the preceding 30 minutes (Ex).Pts with onset during exercise were younger (Ex 59.0 (5010.7), Rest 60.8 (10.4), Bed 61.9 (1 0.6) years, p<0.001) and more likely to be male (Ex 79%, Rest 67%, Bed 67%, p<0.001). Cardiovascular risk factors and time delay to admission were similar for all groups. After adjusting for age and sex, pts whose symptoms began during exercise had a lower mortality (OR 0.63, 95% CI 0.44, 0.90) and had fewer in-hospital cardiac arrests (OR 0.61, CI 0.39, 0.95) than those whose symptoms began at rest. Pre-hospital cardiac arrest was not less likely (OR 1.18, CI 0.82, 1.69). Pts with onset of symptoms in bed had a higher mortality (OR 1.27, CI 1.00, 1.61) than those with onset at rest.Outcome of myocardial infarction is influenced by the activity at the onset of symptoms. This may reflect variations in the pathophysiology of MI occurring under different conditions