Abstract 2925: Relation of Exercise Capacity to Tissue Velocity Indices of Left and Right Ventricular Function in Patients with Dilated Cardiomyopathy
Introduction: Tissue Doppler indices (TDI) permit the evaluation of left and right ventricular function, by filling pressure estimation and measurement of isovolumic events. This study explores the relation of TDI derived indices to an objective measure of functional status, such as peak O2 consumption during treadmill exercise (VO2P).
Methods: We studied 50 pts (aged 16–78 years) with previously diagnosed dilated cardiomyopathy (DCM), left ventricular ejection fraction (LVEF) < 40%. All patients underwent complete Echocardiographic and Tissue Doppler study for the evaluation of early (E) and late (A) mitral inflow velocity, deceleration time of E (DTE), early diastolic mitral annular velocity (Em), systolic mitral annular velocity during isovolumic contraction (SmI), systolic mitral annular velocity (Sm), systolic tricuspid annular velocity during isovolumic contraction (StrI) and systolic tricuspid annular velocity (Str). Subsequently all pts underwent maximal symptom-limited cardiopulmonary exercise test for the evaluation of peak O2 consumption (VO2P) within a week.
Results: Echocardiographic characteristics of these pts were: LVEF 31.5 ± 7.4, E/A:1.46 ± 1.23, DTE: 175 ± 81 ms, E/Em: 12.4 ± 4.6, SmI: 5.1 ± 2.1 cm/sec, Sm: 5.1 ± 1.8 cm/sec, StrI: 8.8 ± 3.5 cm/sec, Str: 12.4 ± 4.6 cm/sec VO2 p 20.5 ± 5.1 ml/kg/min. Correlation coefficients of VO2P with flow and tissue velocity indices were: EF: (r = 0.477, p = 0.001**), E/A (r = 0.42, p = 0.79), DTE (r = 0.156, p = 0.31), E/Em (r = −0.334, p = 0.027*) SmI (r = 0.658, p = 0.0001*), Sm(r = 0.376, p = 0.009*), StrI (r = 0.437, p = 0,0012*), Str (r = 0.558, p = 0.0001*). By multivariate analysis SMI was the only independent predictor of VO2P (r = 0,415 CI = 0.273–2.05 p = 0.012)
Conclusion: Significant relations exist between respiratory gas exchange and TDI derived indices of LV and RV longitudinal function in patients with DCM. Isovolumic contractility of LV as expressed by tissue velocity is the only independent determinant of exercise capacity.