The electrocardiographic abnormalities in highly trained athletes compared to the genetic study related to causes of unexpected sudden cardiac death

Abstract

Background: Electrocardiograms in elite endurance athletes sometimes show bizarre patterns suggestive of inherited channelopathies (Brugada syndrome, long QTc, catecholaminergic polymorphic ventricular tachycardia) and cardiomyopathies (arrhythmogenic right ventricular cardiomyopathy, hypertrophic cardiomyopathy) responsible for unexpected sudden cardiac death. Among other methods, genetic analyses are required for correct diagnosis.

Objective: To correlate 12-lead electrocardiographic patterns suggestive of inherited channelopathies and cardiomyopathies to specific genetic analyses.

Design: Prospective study (2004-2007) of screening 12-lead ECG tracings in standard position and higher intercostal spaces V1 to V3 precordial leads, performed in athletes and normal sedentary subjects aged match. Genetic analyses of subjects with ECG abnormalities suggested inherited channelopathies and cardiomyopathies.

Setting: All cardiologic exams and electrocardiograms were performed at "Prof. Dr. C.C. Iliescu" National Institute of Cardiovascular Diseases (Bucharest, Romania). The genetic studies were done at "Mina Minovici" National Institute of Forensic Medicine (Bucharest, Romania).

Participants: 347 elite endurance athletes (seniors--190, juniors--157), mean age of 20; 200 subjects mean age of 21, belonging to the control group of 505 normal sedentary population.

Results: Seniors. RSR' (V1 to V3) pattern, in 45 cases (23.68%), 5 of them with questionable Brugada sign (elevated J wave and "coved" ST segment, < 2 mm in one lead, V1. Typically, Brugada 1 sign was found in one case (0.52%) with no SCN5A abnormalities. One athlete (0.52%) had normal ECG and exon1 SCN5A duplication. MRI confirmed three arrhythmic right ventricular cardiomypathy epsilon waves (1.57%), in one case. ST-segment elevation myocardial injury like in V1-V3 precordial leads in 34 athletes (17.89%). Genetic analyses-no gene mutations. Juniors. Upright J wave was found in 43 cases (27.38%). Convex ST segment elevation in V1-V3/V4, in 39 cases (24.84%). Bifid T wave with two distinct peaks was found in 39 cases (24.84%), 5 of them with mild prolonged QTc (0.48"-0.56") and KCN genes mutations. Nine (5.73%) of the elevated ST segment juniors had questionable Brugada sign, two of which with KCN (n=1) and SCN5A (n=1) gene mutations. Ajmaline provocative test was negative in 4 and was refused by 5 subjects.

Conclusion: Bizarre QRS, ST-T patterns suggestive of abnormal impulse conduction in the right ventricle, including the right outflow tract, associated with prolonged QTc interval in some cases were observed in highly trained endurance athletes. The genetic analyses, negative in most athletes, identified surprising mutations in SCN5A and KCN genes in some cases.

Fig 1

190 seniors and 157 juniors athletes and their distribution according to type of sport

Fig 2

Senior athlete with spontaneous Brugada sign 1 (arrow) on 12–lead ECG.

Fig 3

ECG abnormalities percent in senior (n=114) and junior (n=113) athletes referred to genetic analysis

Fig 4a

Junior athlete. MLPA profiles for SCN5A gene (SALSA P108, upper panel) and for KCNQ1 and KCNH2 (SALSA P114, lower panel). Possible double mutations (duplication) for exon 18 KCNQ1 and exon 4 KCNH2 (Brug. SALSA P108; LQT. SALSA P114).

Fig 4b

Electrocardiograms of two KCN genes mutations in junior athlete. In standard 12–lead ECG sinus rhythm 62 bpm; bifid T waves and distinct two peaks in V2, V3 precordial leads. (arrow) In higher V1, V2 leads (one upper)–bifid T waves are evident in V2 (arrow); ( two upper spaces) – epsilon wave in V1 (arrow).

Fig 5

Senior athlete. MLPA profiles for SCN5A gene (SALSA P108, upper panel) and for SCN5A, KCNQ1, KCNH2, KCNE1, KCNE2 (SALSA P114, lower panel). No detectable mutations. (Brug. SALSA P108; LQT. SALSA P114).

Fig 6

Senior athlete. MLPA profiles for SCN5A (SALSA P108, upper panel) – possible exon1 duplication. SALSA P 114 (lower panel) for KCNE2, KCNE1, KCNQ1, KCNH2 normal profile. Brug. SALSA P108; LQT. SALSA P114).