Quinidine as a cause of sudden death.

Sudden death and arterial embolism are unpredictable hazards of quinidine therapy for atrial fibrillation that act as deterrents to its most effective use. In this paper an attempt is made to determine the incidence of these accidents as reported in the literature. The mechanism of sudden death is also examined. The difficulty of determining the role of quinidine in producing these accidents in seriously ill patients is clarified. UDDEN death and embolism have long been feared as major hazards of quini-(dine in the treatment of atrial fibrilla-tion. Isolated reports of untoward reactions began to appear shortly after the introduction of the drug by Frey in 1917. Viko, Marvin, and White' compiled the first sizable group of cases in 1923 dealing with this problem. In 484 patients, they reported 9 sudden deaths, 6 of which were presumed to he due to embolism. 'The overall incidence of embolism, fatal and nonfatal, was 3.1 per cent; the incidence of sudden death was 1.8 per ceiit. IIi 1929, 1Parkin-,son and Campbell2 reported oti the basis of 554 cases a 4 per cent incidence of sudden death. This latter figure has been generally accepted as the standard risk. In contrast to the emphasis placed on embolism inl the earlier report, they noted that "hardly any of these *deaths were proved due to emboli, and in most of them necropsy showed no obvious structural disease to account for it [death]". The most recent statistical data were presented by Askey3 in 1946. He reported on 839 cases, segregated into patients with and without congestive heart failure. Of 275 patients in failure, the incidence of death during treatment with quinidine was 4.0 per cent; in 564 cases not in failure, the incidence was 1.8 per (ent. Although no such separation was made in the preceding reports, congestive heart failure was believed to play an adverse role. M\ore recent authors have suggested that the hazards of embolism have been overemphasized, and that sudden death, though a possibility, is rare.4 In the face of these confli(tin-ig data and