Restrictive Mitral Annuloplasty Does Not Limit Exercise Capacity.

BACKGROUND: Restrictive mitral annuloplasty is the preferred method of treating secondary mitral regurgitation. The use of small annuloplasty rings to reduce the high recurrence rates may result in mitral stenosis.

METHODS: Thirty-six patients who underwent restrictive mitral annuloplasty with Carpentier-Edwards classic 26 size ring underwent exercise echocardiography and ergospirometry. Resting catecholamines and N-terminal pro brain natriuretic peptide (NT-proBNP) levels were measured.

RESULTS: At the time of study, the median time from operation was 16.6 months (interquartile range, 8.5 to 43.3 months). Left ventricular end-systolic volume index (LVESVI) was 67 mL/m(2) (interquartile range, 25 to 92 mL/m(2)), and ejection fraction (EF) was 38.8% (interquartile range, 28.3% to 59.0%). Mitral gradients were higher at the leaflet tips than at the annular level. Continuous wave (CW) Doppler gradients at rest were 3.4 mmHg (interquartile range, 2.4 to 4.9 mmHg) mean and 9.5 mmHg (interquartile range, 7.0 to 14.7 mmHg) maximal. On exertion, they increased to 6.8 mmHg (interquartile range, 5.4 to 8.8 mmHg) (p = 0.001) and 19.7 mmHg (interquartile range, 12.8 to 23.3 mmHg) (p = 0.001), respectively. Maximal VO2 was 18.2 mL/kg/min (interquartile range, 16.3 to 21.5 mL/kg/min), VE/VCO2 slope was 31.1 (interquartile range, 26 to 34). Epinephrine level was 0.024 ng/mL (interquartile range, 0.0098 to 0.043 ng/mL), norepinephrine was 0.61 ng/mL (interquartile range, 0.41 to 0.95 ng/mL), and NT-proBNP was 303 pg/mL (interquartile range, 155 to 553 pg/mL). Maximal VO2 negatively correlated with resting norepinephrine level (r = -0.50, p = 0.003). VE/VCO2 slope positively correlated with NT-proBNP (r = 0.36, p = 0.004) and epinephrine (r = 0.36, p = 0.04) levels and with LV volumes (r = 0.51, p = 0.006) and was negatively correlated with LVEF (r = -0.52, p = 0.004). Neither maximal VO2 nor VE/VCO2 slope correlated with the highest mean (r = 0.24, p = 0.2, and r = -0.20, p = 0.3, respectively) and maximal (r = 0.13, p = 0.5, r = -0.20, p = 0.3, respectively) mitral gradients on exertion.

CONCLUSIONS: Restrictive mitral annuloplasty for secondary mitral regurgitation does result in a degree of mitral stenosis; however, primary heart disease seems more important for patient's exercise performance than the mitral stenosis resulting from using an undersized ring.