Cardiac rehabilitation improves functional status and reduces mortality in patients with chronic heart failure with reduced left ventricular (LV) ejection fraction. The presence of exercise oscillatory ventilation (EOV), characterized by the periods of hyperpnea and hypopnea without interposed apnea, may be assessed using cardiopulmonary exercise test (CPET) and is associated with a poor prognosis. We aim to assess the effect of cardiac rehabilitation on EOV in patients with chronic heart failure.

From January 2014 to March 2017, patients with chronic heart failure with ambulatory cardiac rehabilitation program in our center were included. A CPET has been performed in all patients before and after 10-week rehabilitation program. The presence of EOV was defined as duration>60% of total exercise duration with a cycle length of more 30s and an amplitude≥15% of the averaged resting value, as recommended.

Among 40 patients (mean age: 59±8 years, 33 males, mean LV ejection fraction: 30±9), baseline EOV was found in 26 cases (65%). There was no significant difference between patients with EOV (EOV+) and those without EOV (EOV−) regarding risk factors and clinical and demographic data. Before rehabilitation, patients EOV+ had significant lower peak respiratory ratio (1.14±0.07 vs. 1.08±0.081, respectively, P=0.02) and a trend for lower VE/VCO₂ slope (39.9±5.8 vs. 36.1±4.2, respectively, P=0.074). After cardiac rehabilitation, EOV reversed in 13 patients (50%, P=0.001). The thirteen patients who conserved EOV have a decrease of the cycle length (44±10s vs 36±5s, P=0.016).

In patients with chronic heart failure with reduced LV ejection fraction, EOV are present in 65% of cases. A 10-week cardiac rehabilitation program reverses EOV in half of patients and decrease EOV cycle length in those with persisting EOV. Further studies are needed to confirm these results and explore the potential prognostic significance of EOV reversal.