Idiopathic dilated cardiomyopathy in an Omani population of the Arabian Peninsula: prevalence, clinical profile and natural history

We have analysed prospectively the prevalence and clinical profile of idiopathic dilated cardiomyopathy (IDC) in a circumscribed native population of the Sultanate of Oman over 3 years (1992–1994). Identified patients were followed up for a period ranging from 1 to 8 years (median 4 years) and the variables related to outcome determined. IDC was diagnosed in 97 patients, giving a prevalence of 43.2/100,000 population during the study period. 84.5% of patients were aged over 35 years and males outnumbered females (M/F=1.4:1). Factors related to poor outcome were an initial left ventricular ejection fraction ≤30% (P=0.01), severe symptoms, i.e. NYHA functional class III or IV at presentation (P=0.04), and significant ventricular tachycardia during follow up (P=0.02). However, multivariate regression analysis yielded only low LVEF as the predictor of poor outcome (P=0.01). When analysed from age of onset of symptoms, survival figures were 94% at 1 year (95% CI 88 to 99%), 76% at 5 years (95% CI 67 to 86%) and 68% at 8 years (95% CI 54 to 82%). Mean survival was 6.5 years (95% CI 6 to 7 years). Patients were still at risk of fatal ventricular arrhythmia even when haemodynamically stable and had left ventricular ejection fraction >30%.