Functional impact of transmitral gradients at rest and during exercise after restrictive annuloplasty for ischemic mitral regurgitation

Abstract

Objectives: Restrictive mitral valve annuloplasty combined with coronary artery bypass grafting is the treatment of choice for ischemic mitral regurgitation. Postoperative functional mitral stenosis and its potential impact on functional capacity remain the object of debate. The aim of this study was to assess functional and hemodynamic outcome at rest and during exercise in a population with ischemic mitral regurgitation after a standardized restrictive mitral valve annuloplasty.

Methods: A total of 23 patients with ischemic mitral regurgitation who were previously treated with coronary artery bypass grafting and restrictive mitral valve annuloplasty underwent a semi-supine (bicycle) exercise test with Doppler echocardiography and ergospirometry. The surgical technique was identical in all patients, using a complete semi-rigid ring downsized by 2 sizes after measuring the height of the anterior mitral leaflet, to achieve a coaptation length of at least 8 mm.

Results: At a mean follow-up of 28 ± 15 months, mean transmitral gradients at rest and maximal exercise were 4.4 ± 1.8 mm Hg and 8.2 ± 4.2 mm Hg, respectively (P < .001). Transmitral gradients did not correlate with exercise capacity (maximal oxygen uptake) or pulmonary artery pressures. Patients with a resting mean gradient of 5 mm Hg or greater (n = 9) reached a significantly higher maximal oxygen uptake; however, they had a better ejection fraction and cardiac output at rest and reached a higher cardiac output at peak exercise.

Conclusions: Transmitral gradients after restrictive mitral valve annuloplasty for ischemic mitral regurgitation did not correlate with functional capacity as measured by maximal oxygen uptake during semi-supine bicycle testing. Functional capacity and transmitral gradients are determined not only by the severity of mitral stenosis but also by hemodynamic factors, such as ejection fraction and cardiac output. Transmitral gradients should be interpreted with respect to patient hemodynamics and not necessarily be considered as detrimental for functional capacity.