Post-COVID-19 exaggerated exertional tachycardia: Relationship with pulmonary and cardiac sequelae

Background: Long-COVID patients frequently complain of an Exaggerated Exertional Tachycardia (EET) and may represent a specific phenotype of post-COVID tachycardia syndrome. So far, no studies have investigated the factors contributing to EET. Objectives: To determine the predictor factors of EET, seventy-nine Long-COVID-19 patients underwent comprehensive cardiologic and respiratory evaluations at follow-up visit after a median of 23 weeks from the acute phase of the disease. Methods: The heart rate (HR) response to exercise was assessed by the 6-minute walk test (6MWT), stratifying patients into two groups: EET and NET (normal exertional tachycardia). Results: The EET group was older, had higher body mass index and systolic blood pressure, with more comorbidities and lower resting HR, when compared to the NET group. The EET group also showed higher High-Resolution computed tomography scores and D-dimer levels during the acute phase compared to NET. At follow-up visit EET patients exhibited higher left ventricular mass and reduced systolic and diastolic function in both ventricles, as assessed by Doppler tissue echocardiography (myocardial S and E’ waves). We found a significant reduction in lung diffusion capacity and in mean oxygen saturation during the 6MWT in EET patients compared to NET ones. Stepwise logistic regression analysis identified the mean oxygen saturation during the 6MWT as the predictor of abnormal HR response to exercise. Conclusions: We found that the exaggerated heart response to exercise in Long COVID-19 patients is associated to an impaired pulmonary function at rest and is predicted by the oxygen exercise-induced desaturation.