Possible mechanisms of sudden cardiac death in top athletes: a basic cardiac electrophysiological point of view

Abstract

Sudden death among athletes is very rare (1:50,000-1:100,000 annually) but it is still 2-4 times more frequent than in the age-matched control population and attracts significant media attention. We propose a mechanism underlying sudden cardiac death in athletes that does not relate to myocardial ischemia but is based on repolarization abnormalities due to potassium channel downregulation and can also be best explained by the concurrent presence of several factors such as cardiac hypertrophy (athlete's heart), and/or hypertrophic cardiomyopathy, increased sympathetic tone, genetic defects, drugs, doping agents, food, or dietary ingredients. These factors together can increase the repolarization inhomogeneity of the heart ("substrate") and an otherwise harmless extrasystole ("trigger") occurring with a very unfortunate timing may sometimes induce life-threatening arrhythmias. The effective and possible prevention of sudden cardiac death requires the development of novel cost effective cardiac electrophysiological screening methods. Athletes identified by these tests as individuals at higher proarrhythmic risk should then be subjected to more costly genetic tests in order to uncover possible underlying genetic causes for alterations in ionic channel structure and/or function.

Effects of Chelidonium majus extracts and major alkaloids on hERG potassium channels and on dog cardiac action potential — A safety approach

“…Furthermore and even more importantly use of all these alkaloids may have additive effects further increasing the possibility of proarrhythmic risk and cardiac sudden death during administration of drugs effecting the cardiac repolarization or in certain pathophysiological conditions where repolarization reserve is impaired (including cardiac hypertrophy, hypertrophic cardiomyopathy, increased sympathetic tone, genetic defects, diabetes mellitus, renal failure, hypokalemia, hypothyroidism, etc.) [21,22]. In conclusion, the internal use of C. majus extracts or its alkaloids, berberine, chelidonine and especially sanguinarine in some situations where cardiac repolarization reserve is weak may increase the risk of potentially fatal ventricular arrhythmias.…”

The Busy General Practitioner’s Reference Guide to Increasing Physical Activity Levels in the British population and Associated Benefits/Risks: A Review of the Literature

“…Pedometers have been displayed in numerous studies to improve PA levels and are relatively inexpensive in addition to providing instantaneous output measures that are easily analysed by those with low literacy rates [31]. Average improvements over varying time periods up to and including 20 weeks has been calculated at 2,000 steps per day compared to control [32,33].…”

“…Corrado et al [43] found that the relative risk of SCD was 2-4 in young athletes compared to inactive controls. SCD predominantly occurs during periods of medium-low oxygen demand such as during the warm up and inactive periods of matches [31]. Despite the severity of SCD, there is still great debate about the complex aetiological pathways involved [48,49] and the definition of SCD varies between studies [50].…”

Detailed heart rate variability analysis in athletes

“…Intensive research of HRV as a marker of cardiac autonomic function has been carried out in the past few decades [2][3][4]. HRV has been utilized to characterize adverse cardiovascular adaptation in certain disease entities such as ischemic heart disease and heart failure [5,6].…”