Strain Echocardiography and Functional Capacity in Asymptomatic Primary Mitral Regurgitation With Preserved Ejection Fraction.

BACKGROUND

The potential additive utility of baseline resting left ventricular global longitudinal strain (LV-GLS) and exercise stress testing in risk stratification of patients with significant mitral regurgitation (MR) has not been studied.

OBJECTIVES

The goal of this study was to determine whether resting LV-GLS and exercise testing provide incremental prognostic utility in asymptomatic patients with ≥3+ primary MR and preserved left ventricular ejection fraction.

METHODS

Between 2000 and 2011, resting and exercise echocardiography data, Society of Thoracic Surgeons (STS) scores, and death were recorded in 737 patients (mean age 58 ± 13 years; 68% men).

RESULTS

Coronary artery disease and flail leaflet were seen in 10% and 28% of patients, respectively. STS score, resting left ventricular ejection fraction, mitral effective regurgitant orifice, resting right ventricular systolic pressure (RVSP), exercise metabolic equivalents (METs), and percentage of age-/sex-predicted METs were 1.5 ± 1%, 62 ± 2%, 0.45 ± 0.2 cm2, 31 ± 12 mm Hg, 9.8 ± 3, and 115 ± 27, respectively. Median LV-GLS was -21.7%. Within 3 months (interquartile range: 1 to 15 months), 65% underwent mitral valve surgery. At 8.3 ± 3 years, 64 (9%) patients died (0% 30-day post-operative deaths). On multivariable Cox survival analysis, higher STS score (hazard ratio [HR]: 1.14), more abnormal resting LV-GLS (HR: 1.60), higher baseline RVSP (HR: 1.35), and lower percentage of age-/sex-predicted METs (HR: 1.13) were associated with higher mortality, whereas mitral valve surgery (HR: 0.82) was associated with improved survival (all p < 0.01). Addition of predicted METs and resting LV-GLS to STS, resting RVSP, left ventricular end-systolic dimension, and mitral effective regurgitant orifice increased the C-statistic for longer-term mortality from 0.61 to 0.69 and 0.78, respectively (all p < 0.01). On quadratic spline analysis, the risk of death progressively increased as resting LV-GLS worsened below -21%.

CONCLUSIONS

Reduced exercise capacity and worsening resting LV-GLS were associated with mortality, providing additive prognostic utility.