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Exercise capacity in hypertrophic cardiomyopathy depends on left ventricular diastolic function
C Briguori1, S Betocchi, M Romano
1Department of Clinical Medicine and Cardiovascular Sciences, Federico II University School of Medicine, Naples, Italy.
Insights
Left atrial M-mode and pulmonary venous Doppler indexes effectively predict exercise capacity in hypertrophic cardiomyopathy (HC) patients. Diastolic function, not transmitral flow, is key for assessing exercise tolerance in HC.
Area of Science:
- Cardiology
- Echocardiography
- Cardiovascular Physiology
Background:
- Left ventricular (LV) diastolic dysfunction is implicated in reduced exercise capacity in hypertrophic cardiomyopathy (HC).
- Accurate prediction of exercise capacity is crucial for managing HC patients.
Purpose of the Study:
- To evaluate the predictive capability of echocardiographic diastolic function indexes for exercise capacity in HC patients.
- To identify specific echocardiographic parameters that correlate with exercise tolerance in HC.
Main Methods:
- Fifty-two drug-naïve HC patients underwent M-mode and Doppler echocardiography to assess diastolic function.
- Measurements included left atrial fractional shortening and pulmonary venous flow velocities.
- Exercise capacity was quantified using maximum oxygen consumption (VO2 max) via cardiopulmonary exercise testing.
Main Results:
- Maximum oxygen consumption significantly correlated with left atrial fractional shortening and pulmonary venous diastolic velocity.
- Stepwise regression identified left atrial fractional shortening and pulmonary venous systolic filling fraction as independent predictors of VO2 max.
- Doppler-derived transmitral flow indexes did not correlate with exercise capacity.
Conclusions:
- Passive left ventricular diastolic function, assessed by left atrial M-mode and pulmonary venous Doppler, is a primary determinant of exercise capacity in HC.
- These echocardiographic parameters offer valuable insights into exercise limitation in hypertrophic cardiomyopathy.
Abstract:
Some studies have demonstrated that left ventricular (LV) diastolic function is the principal determinant of impaired exercise capacity in hypertrophic cardiomyopathy (HC). In this study we sought the capability of echocardiographic indexes of diastolic function in predicting exercise capacity in patients with HC. We studied 52 patients with HC while they were not on drugs;12 of them had LV tract obstruction at rest. Diastolic function was assessed by M-mode and Doppler echocardiography by measuring: (1) left atrial fractional shortening, and the slope of posterior aortic wall displacement during early atrial emptying on M-mode left atrial tracing; and (2) Doppler-derived transmitral and pulmonary venous flow velocity indexes. Exercise capacity was assessed by maximum oxygen consumption by cardiopulmonary test during cycloergometer upright exercise. Maximum oxygen consumption correlated with the left atrial fractional shortening (r = 0.63, p <0.001), the slope of posterior aortic wall displacement during early atrial emptying (r = 0.55, p <0.001), age (r = -0.50; p <0.001), pulmonary venous diastolic anterograde velocity (r = 0.41, p <0.01), and the systolic filling fraction (r = -0.43; p <0.01). By stepwise multiple linear regression analysis, left atrial fractional shortening and the pulmonary venous systolic filling fraction were the only determinants of the maximum oxygen consumption (multiple r = 0.70; p <0.001). Exercise capacity did not correlate with Doppler-derived transmitral indexes. Thus, in patients with HC, exercise capacity was determined by passive LV diastolic function, as assessed by the left atrial M-mode and Doppler-derived pulmonary venous flow velocities.