Left ventricular markers of global dyssynchrony predict limited exercise capacity in heart failure, but not in patients with preserved ejection fraction

In 147 HF patients (mean age 61？±？11 years, 50.3% male), a 6-MWT and an echo-Doppler study were performed in the same day. Global LV dyssynchrony was indirectly assessed by total isovolumic time - t-IVT [in s/min; calculated as: 60 – (total ejection time？+？total filling time)], and Tei index (t-IVT/ejection time). Patients were divided into two groups based on the 6-MWT distance (Group I: ≤300 m and Group II: >300 m), and also in two groups according to EF (Group A: LVEF？≥？45% and Group B: LVEF？<？45%).In the cohort of patients as a whole, the 6-MWT correlated with t-IVT (r？=？？0.49, p？<？0.001) and Tei index (r？=？？0.43, p？<？0.001) but not with any of the other clinical or echocardiographic parameters. Group I had lower hemoglobin level (p？=？0.02), lower EF (p？=？0.003), larger left atrium (p？=？0.02), thicker interventricular septum (p？=？0.02), lower A wave (p？=？0.01) and lateral wall late diastolic myocardial velocity a’ (p？=？0.047), longer isovolumic relaxation time (r？=？0.003) and longer t-IVT (p？=？0.03), compared with Group II. In the patients cohort as a whole, only t-IVT ratio [1.257 (1.071-1.476), p？=？0.005], LV EF [0.947 (0.903-0.993), p？=？0.02], and E/A ratio [0.553 (0.315-0.972), p？=？0.04] independently predicted poor 6-MWT performance (<300 m) in multivariate analysis. None of the echocardiographic measurements predicted exercise tolerance in HFpEF.In patients with HF, the limited exercise capacity, assessed by 6-MWT, is related mostly to severity of global LV dyssynchrony, more than EF or raised filling pressures. The lack of exercise predictors in HFpEF reflects its multifactorial pathophysiology.Heart failure (HF) has become a major public health problem [1], and its incidence is increasing [2], particularly that caused by systolic left ventricular (LV) dysfunction, which is known to have poor prognosis [3,4]. In patients with systolic HF, systolic [5] and diastolic [6,7] LV velocity parameters, as well as right ventricular [8] function have been shown to