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Tissue Doppler Image-Derived Measurements During Isovolumic Contraction Predict Exercise Capacity in Patients With Reduced Left Ventricular Ejection Fraction

Division of Cardiovascular Diseases, Mayo Clinic, Scottsdale, Arizona

^_* Reprint requests and correspondence: Dr. Partho P. Sengupta, Mayo Clinic Arizona, 777 East Mayo Boulevard, Phoenix, Arizona 85054 (Email: sengupta.partho{at}mayo.edu).

Objectives: We explored the incremental value of quantification of tissue Doppler (TD) velocity during the brief isovolumic contraction (IVC) phase of the cardiac cycle for the prediction of exercise performance in patients referred for cardiopulmonary exercise testing (CPET).

Background: Experimental studies have shown that rapid left ventricular (LV) shape change during IVC is essential for optimal onset of LV ejection. However, the incremental value of measuring IVC velocities in clinical settings remains unclear.

Methods: A total of 82 subjects (age 53 ± 14 years, 56 men) were studied with echocardiography and CPET. Reduced LV ejection fraction (EF) (EF <50%) was present in 38 (46%) subjects. Pulsed-wave annular TD velocities were averaged from the LV lateral and septal annulus during isovolumic contraction (IVCa), ejection, isovolumic relaxation, and early and late diastole (Aa) and compared with peak oxygen consumption (VO₂) and percentage of the predicted peak VO₂ (% predicted peak VO₂) obtained from CPET.

Results: Patients with reduced EF had lower IVCa (6.3 vs. 4.5 cm/s, p = 0.04), ejection (7.7 vs. 5.5 cm/s, p < 0.001), and Aa velocities (7.9 vs. 6.6 cm/s, p = 0.04). Similarly, % predicted peak VO₂ was lower in patients with reduced EF (52.9% vs. 73.1%, p < 0.001) and correlated with the variations in IVCa (r = 0.7, p = 0.001). Multivariate analysis of 2-dimensional and Doppler variables in the presence of reduced LV EF revealed only IVCa and Aa as independent predictors of % predicted peak VO₂ (r² = 0.612, p = 0.02 for IVCa and p = 0.009 for Aa). The overall performance of IVCa in the prediction of exercise capacity was good (area under the curve = 0.86, p < 0.001).

Conclusions: Assessment of TD-derived IVC and atrial stretch velocities provide independent prediction of exercise capacity in patients with reduced LV EF. Assessment of LV pre-ejectional stretch and shortening mechanics at rest may be useful for determining the myocardial functional reserve of patients with reduced EF.

Key Words: left ventricular dysfunction • tissue velocity • exercise capacity

Abbreviations and Acronyms   Aa = annular tissue velocity during late diastolic period   CPET = cardiopulmonary exercise test   Ea = annular tissue velocity during early diastolic period   EF = ejection fraction   IVC = isovolumic contraction phase   IVCa = annular tissue velocity during isovolumic contraction period   LV = left ventricle/ventricular   LVEF = left ventricular ejection fraction   MET = metabolic equivalent   ROC = receiver-operator characteristic   TD = tissue Doppler   VCO2 = carbon dioxide production   VE = minute ventilation   VO2 = oxygen consumption   % predicted peak VO2 = predicted peak oxygen consumption