Low QRS voltages and left ventricular hypertrophy: a risky association

Background: Low-QRS voltages (LQRSV) are an unexpected finding in left ventricular (LV) hypertrophy, i.e, hypertrophic cardiomyopathy (HCM) or athlete's heart. Methods: Prevalence and clinical correlates of LQRSV were investigated in 197 consecutive HCM patients, aged 58±13 years and comparatively in 771 Olympic athletes, aged 23± 4. Clinical characterization included family/personal history, symptoms, NYHA functional class, ECG pattern, ventricular arrhythmias and cardiac magnetic resonance (CMR). Results: 22 (11%) of HCM, and 18 (2.3%) of athletes presented LQRSV. At initial evaluation, in HCM, LQRSV showed no differences vs. non-LQRSV for functional class (90% vs. 91%, in class I-II; p=0.983), symptoms (27% vs. 18%; p=0.478), ventricular arrhythmias (40% vs. 39%; p=857), but showed larger extent of LGE at CMR (4.1±1.5 vs. 1.5±0.7 affected segments; p<0.001). In athletes, LQRSV was associated with larger prevalence of inverted T-waves (22% vs. 9%; p<0.001) and ventricular arrhythmias (28% vs. 8%; p=0.005). In one LQRSV athlete arrhythmogenic cardiomyopathy was identified. Over 4.5±2.6-year follow-up, presence of LQRSV in HCM was associated with larger incidence of functional deterioration (31% vs. 14%; p=0.038); stroke (22% vs. 6%; p=0.008) and ICD implant (27% vs. 10%; p=0.015). No clinical events occurred in LQRSV athletes without initial evidence of cardiac disease. Conclusion: LQRSV are relatively common (11%) in HCM and have clinical relevance, being predictive over a medium-term for a worsening functional class, incidence of stroke and ICD implant. Instead, LQRSV are rare (2.3%) in athletes, but may occasionally be a marker that raises suspicion for underlying cardiac disease at risk.