Mechanoelectric contributions to sudden cardiac death

Time for primary review 28 days. Sudden death, a major problem in developed countries and increasingly so in some underdeveloped countries, justifies research on the mechanisms and identification of patients at high risk of sudden death. Most sudden deaths are secondary to ventricular tachyarrhythmias [1,2]. Primary electrical disturbances, such as Brugada syndrome, long QT syndrome, are rare and account for few sudden deaths. Sudden death as a rule complicates the situation with an underlying cardiac disease with different classes of heart failure [2]. The alteration of the cardiac mechanical properties developing early in heart failure is accompanied by action potential lengthening [3], which is modulated by acute stretch [4–6]. The English theologian and philosopher William of Occam (1280–1349) stated: ‘Entia non sunt multiplicanda praeter necessitatum’. This is recognised as Occam's Razor. Roughly interpreted, it proposes that it is better to have one hypothesis to explain five observations than five hypotheses to explain each one. The cardiovascular clinical parameters used for predicting sudden arrhythmic death ranging through indices of neurohormonal status (i.e. heart rate variability) to indices of electrophysiological substrate (i.e. late potentials, QT dispersion, alternans) are influenced by and associated with mechanical disturbances in heart. Although some of these issues have been related to mechanical factors in previous reviews [6–12], this review describes the possibility that many of the mechano-arrhythmic factors affect a common pathway. Moreover, several arrhythmic mechanisms and their clinical correlates infringe such a pathway. That is, we will try to apply the Occam's Razor principle to this problem. We have to satisfy several criteria to support this contention (Fig. 1). First, the currently accepted situation (Fig. 1A). The black arrows represent the paths taken by the conventional dogma. The etiological factors (Fig. 1A top centre), through a variety of mechanisms act via … *Corresponding author. Tel.: +33-2-4747-4687; fax: +33-2-4747-5919 d.babuty{at}chu.med.univ-tours.fr