Sudden death in high performance athlete with bradycardia and SCN5A gene mutation

ABSTRACT

INTRODUCTION: Sinus bradycardia (SB) at rest is considered normal in athletes and is determined by intrinsic heart rate (HR) reduction and modulations of the autonomic system. However, the possibility of progressive degeneration in association with genetic mutations that determine rhythm alterations should make the marked and persistent BS to be better investigated. CASE REPORT Marathon runner, 28 years, SB with HR < 30 bpm associated with first degree atrioventricular block (AVB) and left ventricular hypertrophy (LVH). Diagnosed with atrial flutter (AF) during a period of high-intensity training, which was treated with ablation. After 16 years of follow-up, he had an ischemic stroke (IS), treated with trombolisys, without neurologic sequelae. After developed episodes of sudden loss of consciousness, which was attributed to seizures resulting from the IS. However, the SB with pauses persisted, despite the improvement in the (LVH) pattern. HOLTER showed HR 36-48-80 bpm, BS rhythm, alternating with atrial ectopic rhythm, episodes of type I 2nd degree AVB and pauses of up to 2.7s. TILT-TEST with marked SB, 1st degree AVB and junctional escape, with accentuation of bradycardia and prolonged pauses to orthostasis, without HR response to sensitization with vasodilator, as well as with atropine. Suspecting genetic mutations that cause hereditary primary electrical diseases, a genetic test was collected. However, the patient had sudden death during sleep, before the result, which revealed a mutation of the SCN5A gene. DISCUSSION: SB, prevalent in athletes, may be accompanied by AVB of varying degrees. In this case, in addition to marked bradycardia, the patient had AF. Despite the causal relationship between mutations in the SCN5A gene and the Brugada Syndrome phenotype, there are atypical clinical manifestations that include, in addition to the set of signs and symptoms of Brugada syndrome, AF, sinus node dysfunction, long QT syndrome, dilated cardiomyopathy , and others. Carriers of SCN5A mutations linked to Brugada syndrome or progressive cardiac conduction system degeneration are at increased risk of sudden death. CONCLUSION: Marked bradycardia in athletes should be investigated and the association with channelopathies leads to phenotypes with aberrant rhythms and progressive degeneration of the cardiac conduction system, which can determine fatal arrhythmias.