Sudden death in patients and relatives with the syndrome of right bundle branch block, ST segment elevation in the precordial leads V(1)to V(3)and sudden death.

BACKGROUND

The syndrome with an electrocardiographic pattern of right bundle branch block, ST segment elevation in leads V(1)to V(3)and sudden death is genetically determined and caused by mutations in the cardiac sodium channel. The inheritance of the disease is autosomal dominant. Sudden death may, however, occur from a variety of causes in relatives and patients with this syndrome.

PATIENTS AND METHODS

Twenty-five Flemish families with this syndrome with a total of 334 members were studied. Affected members were recognized by means of a typical electrocardiogram either occurring spontaneously or after the intravenous administration of antiarrhythmic drugs. Sudden deaths in these families were classified as related or not to the syndrome by analysis of the data at the time of the event, mode of inheritance of the disease, and data provided by survivors. Results Of the 25 families with the syndrome, 18 were symptomatic (at least one sudden death related to the syndrome) and seven were asymptomatic (no sudden deaths related to the syndrome). In total, there were 42 sudden cardiac deaths (12% incidence). Twenty-four sudden deaths were related to the syndrome and all occurred in symptomatic families. Eighteen sudden deaths (43% of total sudden deaths) were not related to the syndrome (nine cases) or were of unclear cause (nine cases). Three of them occurred in two asymptomatic families and the remaining 15 in five symptomatic families. Twenty-four of the 50 affected members (47%) suffered (aborted) sudden death and 18 of the 284 unaffected members (6%). This difference in the incidence of sudden death was statistically significant (P<0.0001). Patients with (aborted) sudden death caused by the syndrome were younger than patients with sudden death of other or unclear causes (38+/-4 years vs 59+/-3 years respectively, P=0.0003).

CONCLUSIONS

In families at high risk of sudden death because of genetically determined diseases, the main cause of sudden death remains the disease. However, almost the half of sudden deaths are caused by unrelated diseases or are of unclear cause. Accurate classification of the causes of sudden death is mandatory for appropriate analysis of the causes of death when designing preventive treatments.