Importance of chronotropic response and left ventricular long-axis function for exercise performance in patients with...

We evaluated the relationship between the degree of chronotropic incompetence and left ventricular (LV) impairment during exercise with severity of exercise intolerance in patients with heart failure and preserved ejection fraction (HFPEF).

All patients underwent exercise echocardiography during bicycle Ergometer exercise with the acquisition of long-axis tissue Doppler imaging (TDI). Peak heart rates during exercise were also recorded and the percentages of maximal age-predicted heart rate (%MPHR) and heart rate reserve (%HRR) were calculated thereby. Besides, cardiopulmonary exercise testing was performed with peak oxygen consumption (VO2) measuring averaged at the highest 30-second during exercise.

Forty HFPEF patients (aged 65±9 years; 75% male) were divided into two groups according to the median of peak VO2: patients with peak VO2<16.5 and ≥16.5 ml/kg/min, respectively. Patients with lower peak VO2 had decreased peak heart rates, %MPHR, %HRR, stroke volume and cardiac indices (LVSI and LVCI) than those with higher peak VO2 (all p<0.05). The LV long-axis functions (TDI Sm, Em, s' and e') were reduced in patients with lower peak VO2 (all p<0.05). Moreover, peak VO2 correlated with the following parameters: peak heart rates, %MPHR, %HRR, LVSI, LVCI, TDI Sm, Em, s' and e'(all p<0.05).

The degree of blunted chronotropic response and impaired LV long-axis function were more profound in HFPEF patients with poor exercise performance.