Key result
Hypercontractile phenotype in preserved EF HCM is linked to ~26% lower stroke volume and elevated E/e'.
Why the study?
The functional significance of the left ventricular hypercontractile phenotype in hypertrophic cardiomyopathy remains unclear.
Does a hypercontractile phenotype correlate with adverse systemic and coronary parameters in patients with hypertrophic cardiomyopathy?
Does a hypercontractile phenotype correlate with adverse systemic and coronary parameters in patients with hypertrophic cardiomyopathy?
In HCM patients with preserved EF, a hypercontractile phenotype is associated with reduced stroke volume, impaired diastolic function, and increased resting coronary flow velocity, suggesting inefficient myocardial mechanics.
Background The functional significance of the left ventricular (LV) hypercontractile phenotype (HP) in hypertrophic cardiomyopathy (HCM) remains unclear. Purpose To assess the systemic and coronary hemodynamic correlates of HP in HCM. Methods We enrolled 1533 HCM patients (age 51 ± 15 years, 965 males, 63%) with ejection fraction (EF) ≥50%, referred for rest transthoracic echocardiography (TTE) in 27 laboratories from 13 countries. Two-dimensional volumetric TTE assessment included LV outflow tract gradient (LVOTG), end-diastolic volume (EDV), end-systolic volume (ESV), EF, and LV force (systolic blood pressure + LVOTG/ESV, mmHg/mL). Coronary flow velocity in the mid-distal left anterior descending (LAD) coronary artery was assessed in 325 patients. HP was defined as the highest quartile of the force (> 7.32 mmHg/ml). Results Force was moderately related to EF (r = 0.48, p < 0.0001) and weakly to LVOTG (r = 0.36, p < 0.0001). Compared to non-HP patients, HP showed higher heart rate (72 ± 14 vs 67 ± 14 beats per minute, p <0.0001), lower stroke volume (50 ± 22 vs 67 ± 22 ml, p < 0.0001), larger left atrial volume index (44 ± 16 vs 40 ± 16 ml/m2, p = 0.011) and higher coronary flow velocity in the LAD (n = 325, 41 ± 12 vs 37 ± 14 cm/s, p = 0.021), see Figure. Abnormal B-lines (≥ 2) were present in 11 of the 39 HP compared to 39 of the 271 non-HP patients (28% vs 14 %, p = 0.05). E/e’ ratio was higher in HP (n = 59) vs. non-HP (n = 571) patients (11 ± 5.4 vs 9.6 ± 4.2, p = 0.018). Conclusion In patients with HCM, preserved EF, and no history of coronary artery disease, HP identified by resting TTE with supernormal LV force was associated with an unfavorable systemic hemodynamic and coronary flow profile. Compared to non-HP HCM patients, the HP was characterized by reduced stroke volume, impaired diastolic function, and increased resting coronary flow velocity. HP may reflect inefficient myocardial mechanics, with disproportionate energy expenditure mirrored by higher resting coronary flow despite reduced stroke volume generation, ultimately contributing to adverse remodeling and worse prognosisNon-HP vs HP LAVI and coronary LAD flow
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Wierzbowska-Drabik et al. (2025) studied this question. In HCM patients with preserved EF, hypercontractile phenotype showed 26% lower stroke volume, higher heart rate, elevated E/e' ratio, and increased LAD flow velocity.
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