Early mitral inflow velocity to left ventricular global strain ratio predicts limited exercise capacity.

Background: Estimation of left ventricular filling pressure (LVFP) is the essential part of the echocardiographic workup for exercise intolerance. The ratio of the mitral early filling velocity to the left ventricular global longitudinal strain (E/LVGLS) has emerged as a novel index of LVFP. This study aimed to investigate the relationship between E/LVGLS and exercise capacity.
Methods and Results: We retrospectively reviewed 90 patients with exertional dyspnea who underwent echocardiography and cardiopulmonary exercise test. Patients were classified into three groups according to their percent-predicted maximal oxygen consumption (ppVo ₂ ) (G ≧ 75, ppVo ₂  > 75%, n = 20; G 50-75, ppVo ₂ 75-50%, n = 57; G < 50, ppVo ₂  < 50%, n = 13). Measurements were (a) the relationship between ppVo ₂ and E/LVGLS and (b) the efficiency of integrated diastolic assessment using E/LVGLS, left ventricular volume, mitral annular early diastolic velocity (E'), and tricuspid regurgitation to identify the patient with impaired exercise capacity. Univariate linear regression analysis demonstrated that E/LVGLS had significant correlation with ppVo ₂ (ρ = 0.52, P < 0.001). The area under the ROC of E/LVGLS for ppVo ₂  < 50% was 0.86 (95%CI 0.75-0.97). The DeLong test showed that E/LVGLS was efficient to detect ppVo ₂  < 50% than E/E' (P = 0.007). When used in the integrated assessment of LVFP as the alternative for E/E', E/LVGLS improved risk classification for impaired exercise capacity.
Conclusion: E/LVGLS may be a more efficient index than E/E' to identify exercise impairment as a single index and as a part of the integrated diastolic assessment.
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