R' wave in precordial leads V1-V2 in patients from the young SCD-SOS cohort

Abstract Introduction Sudden Cardiac Death – Screening Of risk factorS (SCD-SOS) survey aimed to screen for warning signs of potential channelopathies and cardiomyopathies that may course with sudden cardiac death in the young (≤40 years old) and consisted in an ECG and a digital-based previously validated questionnaire. Purpose We aimed to study clinical and electrocardiographic characteristics of young patients from the SCD-SOS cohort who presented with an r'-wave in precordial leads V1 and V2. Methods All the ECG were screened for the detection of an r'-wave in precordial leads V1 and V2. The ECGs selected were reviewed by a second investigator (agreed in 97.7% of the cases). We performed classical descriptive statistics and multivariate logistic regression to compare patients with and without r'-wave in these leads. Results From a total of 14669 patients who had an ECG performed as part of the SCD-SOS survey, 17% displayed an r'-wave in precordial leads V1 and V2 and 0.4% had complete right bundle branch block (RBBB). Patients with rSr' pattern had a mean age of 20±5 years old, 54% of them were male, they had a mean body mass index (BMI) of 22±3kg/m2, and 54% practiced sports regularly, with a mean of 5±4 hours of physical activity per week. Regarding previous symptoms reported by these individuals, 24% (n=487) reported a transient loss of consciousness, 15% (n=310) a reflex syncope, 3% (n=58) had unexplained syncope and 21% (n=425) palpitations. Sudden death in relatives before 50 years-old was present in 11% (n=172) of the patients with an r'-wave in V1-V2. After adjusting for heart rate and physical activity, PQ interval (OR 1.007 - CI95% 1.004–1.010, p<0.001), QTc interval (OR 1.009 - CI95% 1.005–1.012, p<0.001), male gender (OR 2.438 - CI95% 2.144–2.772, p<0.001) and BMI (OR 0.881 - CI95% 0.864–0.900, p<0.001) were independently associated with the presence of r'wave in precordial leads V1-V2. Unexplained syncope, palpitations and family history of sudden death were not associated with r'-wave in the young SCD-SOS population. Conclusions We conclude that r'-wave in V1-V2 is a frequent finding in the young population and that it is associated with higher PQ and QTc intervals. The prognostic implications of this pattern are unknown, but thorough differential diagnosis is warranted since this pattern may correspond to incomplete RBBB/athlete's ECG, and may also be suggestive of other potentially serious conditions such as Type 2 Brugada pattern and multiple causes of right ventricular enlargement. Finally, this pattern is also associated with male gender and lower BMI, suggesting a dependence on anatomical factors.