Cardiorespiratory abnormalities in patients recovering from COVID-19

Aims: Large number of patients around the world are recovering from COVID-19; many of them report persistence of symptoms. We sought to test pulmonary, cardiovascular and peripheral responses to exercise in patients recovering from COVID-19.

Methods and Results: We prospectively evaluated 71 patients who recently recovered from COVID-19 using a combined anatomic/functional assessment. All patients underwent clinical examination, laboratory tests, lung ultrasound and combined stress echocardiography and cardiopulmonary exercise test. We measured left ventricular volumes, ejection fraction, stroke volume, heart rate, E/e` ratio, right ventricular function, O2 consumption, lung volumes, Ventilatory efficiency, O2 saturation and muscle O2 extraction in all effort stages and compared them to normal reference values and historical controls. Patients were assessed 90.6±26 days after onset of COVID-19 symptoms. Only 23 (33%) were asymptomatic. The most common symptoms were fatigue (34%), muscle weakness (27%) and dyspnea (22%). Peak O2 consumption<85% from expected was common (n=42; 59%). Reduction in peak O2 consumption was unrelated to severity of disease at the acute phase and was due to a combination of chronotropic incompetence (n=53; 75%) and attenuated stroke volume reserve (Δ Stroke volume<20% in 21; 30%). Attenuated stroke volume reserve was mostly due to diminished increase in left ventricular volume (49%) and abnormal right ventricular systolic reserve (11%) during stress. Chronotropic incompetence, limited stroke volume reserve, attenuated muscle O2 extraction and diminished right ventricular systolic reserve were the only independent factors associated with reduced exercise capacity.

Conclusions: Patients recovering from COVID-19 have symptoms associated with objective reduction in peak VO2, unrelated to severity of the acute disease. The mechanism of this reduction is complex and mainly involves a combination of attenuated heart rate and stroke volume reserve.