Cardiorespiratory Abnormalities in Patients Recovering from COVID-19

Szekely, Yishay; Lichter, Yael; Sadon, Sapir; Lupu, Lior; Taieb, Philippe; Banai, Ariel; Sapir, Orly; Granot, Yoav; Hochstadt, Aviram; Friedman, Shirley; Laufer-Perl, Michal; Banai, Shmuel; Topilsky, Yan

Background Large number of patients around the world are recovering from COVID-19; many of them report persistence of symptoms. Objectives We sought to test pulmonary, cardiovascular and peripheral responses to exercise in patients recovering from COVID-19. Methods We prospectively evaluated patients who recovered from COVID-19 using a combined anatomic/functional assessment. All patients underwent clinical examination, laboratory tests, and a combined stress echocardiography and cardiopulmonary exercise test. We measured left ventricular volumes, ejection fraction, stroke volume, heart rate, E/e' ratio, right ventricular function, VO2, lung volumes, Ventilatory efficiency, O2 saturation and muscle O2 extraction in all effort stages and compared them to historical controls. Results A total of 71 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/pain (27%) and dyspnea (22%). VO2 was lower among post-COVID-19 patients compared to controls (p=0.03, group by time interaction p=0.007). Reduction in peak VO2 was due to a combination of chronotropic incompetence (75% of post-COVID-19 patients vs. 8% of controls, p<0.0001) and insufficient increase in stroke volume during exercise (p=0.0007, group by time interaction p=0.03). Stroke volume limitation was mostly explained by diminished increase in left ventricular end-diastolic volume (p=0.1, group by time interaction p=0.03) and insufficient increase in ejection fraction (p=0.01, group by time interaction p=0.01). Post-COVID-19 patients had higher peripheral O2 extraction (p=0.004) and did not have significantly different respiratory and gas exchange parameters compared to controls. Conclusions Patients recovering from COVID-19 have symptoms associated with objective reduction in peak VO2. The mechanism of this reduction is complex and mainly involves a combination of attenuated heart rate and stroke volume reserve.