European Heart Journal (1987) 8,912-916 Ventricular fibrillation induced by transesophageal atrial pacing in hypertrophic cardiomyopathy

Sudden death is a rather frequent occurrence in patients with hypertrophic cardiomyopathy, yet the mechanism is uncertain in most cases. We describe a case of an 18 years old patient with a family history of hypertrophic cardiomyopathy and sudden death in whom ventricular fibrillation could be repeatedly induced by means of transesophageal atrial stimulation with 1:1 AV conduction at a rate of 200 beats min~ ' and prevented by pharmacological depression of A Vnode. The not particularly high ventricular rate at which VF occurred could suggest that in hypertrophic cardiomyopathy a major role in favouring VF induction is played by the electro-physiological properties of the myocardium and that sudden death can occur as a consequence of different atrial tachy arrhythmias. The annual mortality rate from hypertrophic cardiomyopathy (HCM) is reported to be 2-5 to 6%'''21. A relationship between mortality rate and ventricular tachycardia (VT) has been established'3"51, while atrial arrhythmias seem to confer an increased risk of sudden death either by inducing hypotension and cardiac arrest secondary to inadequate ven-tricular filling161 or by rapid atrio-ventricular con-duction precipitating ventricular fibrillation (VF) in subjects with an associated accessory pathway. This latter possibility has been shown by Krikler et a/.'71 who presented a case with HCM and a right-sided accessory pathway in which VT followed by VF was induced by rapid atrial stimulation. We report on the possibility that a not particularly high ventricular rate, achieved by atrial pacing, can produce VF in a young patient with HCM. Case report A 16-year old girl was referred to our Institution in June 1977 because of atypical chest pain. Her father had died suddenly at the age of 50 years and so had 2 sisters (2 and 9 years old) and 2 brothers (16 and 17 years old) while 4 other brothers had cardiac abnormalities. Submitted for publication on 4 August 1986 and in revised form