Noninvasive identification and therapeutic implications of supernormal left ventricular contractile phenotype
Left ventricular (LV) function is typically evaluated through LV ejection fraction (EF), a robust indicator of risk, showing a nonlinear increase in mortality rates below 40%. Conversely,
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Left ventricular (LV) function is typically evaluated through LV ejection fraction (EF), a robust indicator of risk, showing a nonlinear increase in mortality rates below 40%. Conversely, excessively high EF values (> 65%) also correlate with elevated mortality, following a U-shaped curve, with its nadir observed between 50% and 65%. This underscores the necessity for improved identification of the hypercontractile phenotype. However, EF is not synonymous with LV contraction function, as it can fluctuate independently of contractility due to variations in afterload, preload, heart rate, and ventricular-arterial coupling. Assessing the contractile status of the LV requires more specific metrics, such as LV elastance (or contractile force) and global longitudinal strain. Current guidelines outline various parameters for a more precise characterization of LV contractility, yet further research is warranted for validation. The true hypercontractile phenotype is evident in cardiac pathologies such as hypertrophic cardiomyopathy, ischemia with angiographically normal coronary arteries, Tako-tsubo syndrome, heart failure with preserved EF, and may also stem from systemic disorders including anemia, hyperthyroidism, liver, kidney, or pulmonary diseases. The hypercontractile phenotype constitutes a distinctive hemodynamic substrate underlying clinical manifestations such as angina, dyspnea, or arrhythmias, presenting a target for intervention through beta-blockers or specific cardiac myosin inhibitors. While EF remains pivotal for clinical classification, risk stratification, and therapeutic decision-making, integrating it with other indices of LV function can enhance the characterization of the hypercontractile phenotype.
Yi Wang, Lixue Yin
Left ventricular (LV) function is typically evaluated through LV ejection fraction (EF), a robust indicator of risk, showing a nonlinear increase in mortality rates below 40%. Conversely, excessively high EF values (> 65%) also correlate with elevated mortality, following a U-shaped curve, with its nadir observed between 50% and 65%. This underscores the necessity for improved identification of the hypercontractile phenotype. However, EF is not synonymous with LV contraction function, as it can fluctuate independently of contractility due to variations in afterload, preload, heart rate, and ventricular-arterial coupling. Assessing the contractile status of the LV requires more specific metrics, such as LV elastance (or contractile force) and global longitudinal strain. Current guidelines outline various parameters for a more precise characterization of LV contractility, yet further research is warranted for validation. The true hypercontractile phenotype is evident in cardiac pathologies such as hypertrophic cardiomyopathy, ischemia with angiographically normal coronary arteries, Tako-tsubo syndrome, heart failure with preserved EF, and may also stem from systemic disorders including anemia, hyperthyroidism, liver, kidney, or pulmonary diseases. The hypercontractile phenotype constitutes a distinctive hemodynamic substrate underlying clinical manifestations such as angina, dyspnea, or arrhythmias, presenting a target for intervention through beta-blockers or specific cardiac myosin inhibitors. While EF remains pivotal for clinical classification, risk stratification, and therapeutic decision-making, integrating it with other indices of LV function can enhance the characterization of the hypercontractile phenotype.