Systolic function reserve using two-dimensional strain imaging in hypertrophic cardiomyopathy: comparison with...

Area of Science:

• Cardiology
• Echocardiography
• Cardiovascular Imaging

Background:

• Patients with hypertrophic cardiomyopathy (HCM) often present with normal resting ejection fractions.
• Despite normal resting ejection fraction, HCM patients may have impaired systolic function reserves, limiting exercise capacity.
• Comparing HCM patients with hypertensive (HTN) patients helps elucidate distinct cardiac reserve differences.

Purpose of the Study:

• To investigate differences in systolic function reserve and exercise capacity between patients with HCM and HTN.
• To evaluate the utility of two-dimensional strain imaging in assessing cardiac function during exercise in these patient groups.

Main Methods:

• Utilized resting and peak exercise echocardiography with 2D strain imaging in 40 HCM patients, 20 HTN patients, and 33 controls.
• Measured longitudinal and circumferential strain, LV twist, and LV systolic dyssynchrony (standard deviation of time to peak strain).
• Calculated functional systolic reserve as the difference between peak exercise and resting values, divided by the resting value.

Main Results:

• HCM patients showed significantly lower resting longitudinal strain and strain rates, but higher resting circumferential strain and twist compared to HTN and controls.
• Functional systolic reserve was markedly attenuated in HCM patients (-23%) compared to controls (17%) and HTN patients (10%).
• Exercise significantly amplified LV dyssynchrony in HCM patients, which correlated with exercise capacity, alongside resting LV dyssynchrony and diastolic function.

Conclusions:

• HCM patients demonstrate significantly limited systolic function reserve and increased dynamic dyssynchrony during exercise compared to HTN patients.
• Two-dimensional strain imaging during stress is a promising method for identifying patients at higher cardiovascular risk.
• Findings highlight distinct pathophysiological mechanisms affecting exercise capacity in HCM versus HTN.