Low QRS voltages and left ventricular hypertrophy: a risky association

Low QRS voltages (LQRSV) are an unexpected finding in left ventricular hypertrophy, i.e. hypertrophic cardiomyopathy (HCM) or athlete's heart.

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, New York Heart Association (NYHA) functional class, electrocardiographic pattern, ventricular arrhythmias, and cardiac magnetic resonance (CMR). Twenty-two (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 Classes I and II; P = 0.983), symptoms (27% vs. 18%; P = 0.478), and ventricular arrhythmias (40% vs. 39%; P = 857) but showed larger extent of late gadolinium enhancement (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 implantable cardioverter defibrillator (ICD) implant (27% vs. 10%; P = 0.015). No clinical events occurred in LQRSV athletes without initial evidence of cardiac disease.

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.