Prolonged QT interval in alcoholic autonomic nervous dysfunction.

QT prolongation on electrocardiography is related to sudden cardiac death and is frequently found in alcoholics. We studied QT prolongation in relation to the function of cardiac autonomic nerves assessed by the coefficient of variation of the R-R interval (CVRR) in three age-matched groups of men: 32 alcoholics with autonomic nervous dysfunction (AN), 32 alcoholics without AN, and 32 healthy controls. The QTc interval and CVRR were measured at rest on the 30th day of abstinence, when electrolyte imbalance had disappeared. Subjects with arrhythmia, conduction abnormality, cardiomegaly, ischemic heart disease or diabetes mellitus were excluded. A CVRR of less than 80% of standard predicted value was judged to represent AN. In alcoholics, QTc correlated negatively with the ratio of CVRR to its standard value (r = -0.49, p < 0.0001). The incidence of QTc prolongation was higher in alcoholics with AN (46.9%) than in alcoholics without AN (21.9%, p < 0.05). QTc prolongation was not observed in healthy controls. The QTc interval was significantly (p < 0.01) longer in alcoholics with AN (444 +/- 20 msec) than in alcoholics without AN (426 +/- 17) and in healthy controls (398 +/- 18). These results suggest that alcoholism causes dysfunction of the autonomic nerves as well as worsening QT prolongation, and this may predispose such patients to sudden cardiac death.