Comparison of the correlation of rebreathing method and echocardiography in heart failure patients with moderate to severe mitral regurgitation.

OBJECTIVE To follow-up and estimate cardiac function in 11 heart failure patients with moderate to severe mitral regurgitation who underwent cardiac resynchronization therapy (CRT) and to compare echocardiography to the rebreathing method (indirect Fick method) which were used for estimation. DESIGN Prospective, observational, clinical study. SETTING University teaching hospital. METHODS Eleven cases (8 males and 3 females) were selected and followed-up during presurgery, postsurgery, and 1, 3, and 6 months after pacemaker implantation. Stroke volume was measured by echocardiography (Simpson's method and velocity-time integral method) and rebreathing each time. RESULTS Correlations were found between stroke volume with the rebreathing method (RSV) and stroke volume with the velocity-time integral (VSV), R = 0.89, although ANOVA, the q test, and paired t test showed no statistical differences between them. Stroke volume with Simpson's rule (SSV) was poorly correlated with stroke volume using the Indirect Fick method (RSV) and with stroke volume using the velocity-time integral method (VSV) (R = 0.58 and 0.54, respectively). CONCLUSION The rebreathing method (indirect FICK method) and velocity-time integral method are noninvasive methods with which to measure cardiac function and exhibited good correlation during the follow-up study.