Background: In spite of a total mortality reduction in recent years, sudden cardiac death (SD) remains a major problem in patients with idiopathic dilated cardiomyopathy (IDC) and its occurrence is often unpredictable. Furthermore, the risk of SD may change during follow-up because of the natural history of the disease and the effects of therapeutic interventions. In our study, we evaluated the modifications of the risk of SD during follow-up in a cohort of patients with IDC and analyzed the variables predicting SD not only at enrolment but also at the last examination during optimal medical treatment.
Methods: Since 1978, 343 consecutive patients with IDC were enrolled in the Heart Muscle Disease Registry of Trieste (Italy) and submitted to complete invasive and non-invasive study. Patients were re-evaluated usually at intervals of 12 months.
Results: After a mean of 68+/-45 months, 125 events (death, heart transplantation or aborted SD) had occurred. The cumulative risk after 5 years was 30%, while after 10 years it almost doubled (54%). During the first 3 months after enrolment, the incidence of SD was high (3%). A plateau, lasting about 3.5 years, followed. A slow but progressive rise in the risk of mortality then occurred (6% at 5 years, 18% at 10 years). No variables evaluated at enrolment were associated with SD at multivariate analysis. On the other hand, the end-diastolic left ventricular diameter (> or = 38 mm/m2) and ejection fraction (< or = 0.30) were predictive of SD if evaluated within 1 year before the event. Beta-blocker treatment was associated with a non-significant reduction of risk.
Conclusions: In patients with IDC the incidence of SD progressively increased during long-term follow-up, especially in those with persistent severe left ventricular dilation and dysfunction who were not on beta-blocker treatment. Serial clinical evaluation may help to select patients at higher risk for SD.