Diastolic Stress Echocardiography in Patients With Hypertrophy Cardiomyopathy: Association With Exercise Capacity

Area of Science:

• Cardiology
• Cardiovascular Imaging
• Exercise Physiology

Background:

• Diastolic dysfunction is a key factor in congestive heart failure development in hypertrophic cardiomyopathy (HCM) patients.
• Symptoms in HCM patients often manifest during exercise due to increased left ventricular (LV) filling pressures.
• Abnormal post-exercise diastolic parameters may correlate with diminished exercise capacity.

Purpose of the Study:

• To determine if abnormal post-exercise diastolic parameters are associated with reduced exercise capacity in HCM patients.
• To investigate the relationship between exercise-induced diastolic dysfunction and functional capacity in HCM.
• To evaluate the diagnostic utility of stress echocardiography in assessing exercise limitations in HCM.

Main Methods:

• Examined 590 asymptomatic/minimally symptomatic HCM patients using 2D and Doppler echocardiography at rest and post-maximal treadmill exercise.
• Recorded complete echocardiograms including LV ejection fraction, LV thickness, LV outflow tract (LVOT) gradient, and mitral regurgitation.
• Assessed diastolic parameters (e.g., E/e', E/A ratio, RVSP, left atrial volume index) and exercise capacity (METs).

Main Results:

• 32% of patients had moderate mitral regurgitation post-exercise; mean LVOT gradient was 61±59 mm Hg.
• Only 42% achieved >85% of age-gender predicted metabolic equivalents (AGP-METs), with a mean of 7±3 METs.
• Higher BMI, β-blocker use, left atrial volume index, peak stress LVOT gradient, peak stress E/e', and RVSP were independently associated with <85% AGP-METs.

Conclusions:

• Abnormal diastolic response to exercise is significantly and independently associated with reduced exercise capacity in HCM patients.
• Incorporating diastolic parameters from stress echocardiography can enhance the diagnosis of dyspnea causes in HCM.
• Stress echocardiography provides valuable insights into exercise limitations in hypertrophic cardiomyopathy.