Impact of left ventricular diastolic function on exercise capacity in patients with chronic mitral regurgitation: an exercise echocardiography study.
BACKGROUND
Mitral regurgitation (MR) is known as one of the most frequent causes of heart failure and sudden death. In spite of increasing prevalence of MR, there have been no available data on cardiac determinants of exercise capacity in patients with chronic MR.


OBJECTIVE
This study aimed to investigate cardiac determinants of exercise capacity in patients with chronic MR.


METHODS
We consecutively enrolled 32 patients (11 men, mean age: 44 +/- 14 years) who had greater than moderate MR with normal left ventricular (LV) systolic function (LV ejection fraction >50%). Conventional echocardiographic indices and parameters measured by Doppler tissue imaging at septal side of mitral annulus were obtained before exercise. Mitral regurgitation fraction, forward stroke volume, pulmonary venous flow velocities, and systolic pulmonary artery pressure (sPAP) were also obtained with standard methods.


RESULTS
Left ventricular ejection fraction was 61 +/- 6% and MR fraction was 48 +/- 13%. All patients finished a symptom-limited treadmill exercise test with a peak heart rate of >85% of predicted maximum heart rate. Mean exercise time was 9.95 +/- 2.17 min, corresponding to 11 +/- 2 metabolic equivalents. Among pre-exercise echocardiographic variables, only early diastolic mitral annulus velocity (E') and pulmonary venous reversal flow velocity (PVa) showed a significant correlation with exercise time (r = 0.44, p = 0.011, and r = -0.40, p = 0.040, respectively), which persisted after multivariate analysis (p = 0.011 and 0.038, respectively). Other parameters such as systolic mitral annulus velocity, resting and postexercise sPAP, forward stroke volume, LV size, LV ejection fraction, left atrial size, and regurgitant fraction showed no significant correlation.


CONCLUSIONS
Left ventricular diastolic function is an important determinant of exercise capacity in patients with chronic MR. Both E' and PVa, accepted surrogate estimates for LV diastolic function, may be useful for identifying patients with chronic MR and with poor exercise capacity.
Kim
Hyung-Kwan
HK
Division of Cardiology, Department of Internal Medicine, Seoul Nation University College of Medicine, Seoul, Korea.
Kim
Yong-Jin
YJ
Chung
Joong-Wha
JW
Sohn
Dae-Won
DW
Park
Young-Bae
YB
Choi
Yun-Shik
YS
D000328:Adult; D000368:Aged; D002908:Chronic Disease; D003971:Diastole / Q000502:physiology; D015150:Echocardiography, Doppler; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D008944:Mitral Valve Insufficiency / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D013318:Stroke Volume / Q000502:physiology; D016277:Ventricular Function, Left / Q000502:physiology*