Impact of age and sex on sudden cardiovascular death following myocardial infarction

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Abstract
Objective: To evaluate and compare the risk of sudden cardiovascular death (SCD) and non-SCD after myocardial infarction (MI) associated with age and sex. Design: Cohort study of patients admitted with an enzyme verified acute MI and discharged alive. Patients were followed up for up to four years. Patients: 5983 consecutive hospital survivors of acute MI were enrolled in the TRACE (trandolapril cardiac evaluation) registry from 1990–92. Four age groups were prespecified: < 56, 56–65, 66–75, and ≥ 76 years. Main outcome measures: SCD was defined as cardiovascular death within one hour of onset of symptoms. Results: There were 536 SCD and 725 non-SCD. SCD mortality was 4.8% in the youngest and 15.7% in the oldest age groups. Non-SCD mortality was 3.5% and 25%, respectively. The ratio of SCD to non-SCD mortality varied from 1.44 in the youngest (< 56 years) to 0.55 in the oldest patients (≥ 76 years). Age significantly increased both SCD and non-SCD risk (p < 0.0001), but the increase in non-SCD risk was 40% higher (p < 0.0001). Male sex was associated with increased risk of SCD independently of age (risk ratio 1.34, p < 0.005). However, the absolute three year probability of SCD among women older than 66 years exceeded 10%. Conclusions: Compared with non-SCD the risk of SCD is relatively highest in the younger age groups, but the absolute risk of SCD is much higher among the upper age groups than the younger. The risk of SCD was slightly lower in women but not enough to warrant a different treatment strategy.