Sudden cardiac death after early-onset myocardial infarction. A multicentre longitudinal cohort study with 20 years' follow-up.

Background: Sudden cardiac death (SCD) is a serious consequence of a myocardial infarction (MI), but identifying patients at risk of developing SCD remains a major clinical challenge especially in the case of juvenile MI. The aim of this study was to identify predictors of SCD after early-onset MI using long-term follow-up data relating to a large nationwide patient cohort.
Methods: The Italian Genetic Study on Early-onset MI enrolled 2,000 patients experiencing a first MI before the age of 45 years, who were followed up for a median of 19.9 years. Fine-Gray proportional hazard models were used to assess the associations between their clinical, demographic and index event data and the occurrence of SCD.
Results: SCD occurred in 195 patients, who were more frequently males, hypertensive and/or diabetic; had a history of previous thromboembolic events with a greater atherosclerotic burden; and had a lower left ventricular ejection fraction (LVEF) after the index event. Multivariable analysis showed that the independent predictors of SCD were diabetes, hypertension, previous thromboembolic events, higher Syntax score, and a lower LVEF. There was no clear evidence of the clustering of SCD events during follow-up. SCD was the first post-MI clinical event in 101 patients; the remaining 94 experienced SCD after a non-fatal MI or hospitalisation for coronary revascularisation.
Conclusions: SCD frequently occurs during the 20 years after early-onset MI. The nature of the identified predictors and the absence of clustering suggests that the pathophysiological basis of SCD may be related to progressive coronary atherosclerosis.
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