Marked self-limiting sinus bradycardia in COVID-19 patients not requiring therapy in the intensive care unit - case series report.

Cardiovascular complications of the COVID-19 comprise cardiac arrhythmias, including sinus bradycardia (SB). CASE REPORTS: The authors present clinical data of 19 hospitalized patients (12 males), aged 20-73 years, with marked (less than 45/min during daily hours) self-limiting SB. None of them had SB at admission or earlier, none had used cardiovascular medications potentially decreasing the heart rate. Pulmonary involvement was severe in 4, moderate in 13 and mild in 2 patients; 14 needed oxygen therapy (4 using high flow oxygen equipment), none required treatment in the intensive care unit. All patients were given low molecular weight heparin in a prophylactic dose, 13 intravenous ceftriaxone, 12 dexamethasone, 8 convalescent plasma. Before SB appearance, 12 patients were treated with remdesivir (3 patients did not receive a full planned dose) and 2 with tocilizumab. SB appeared suddenly on day 5-14 from the onset of the disease, with a minimal heart rate of 32-44/min and in 3 cases it was mildly symptomatic; 2 of those received ad-hoc atropine, one orciprenaline. Interleukin-6 (Il-6) and C-reactive protein (CRP) concentrations at SB onset were significantly lower than at admission (9.3 vs 70.0 pg/ml and 16.8 vs 98.5 mg/l, respectively). Cardiac troponin I was slightly elevated in 2 patients. ECG morphology abnormalities (transient negative T waves or ST depression) were found in 4 males. All subjects had normal left ventricular ejection fraction; in 5 echocardiography revealed small pericardial effusion; in 10 patients, longitudinal strain was also studied: reginal abnormalities were found in all of them, particularly in basal segments. SB lasted 3-11 days and was reversible in all patients; none required temporary stimulation. The COVID-19 course was favorable in all patients; they were stable at discharge. During 4-12 months of posthospital observation, including clinical features, control ECG and 24-hour Holter monitoring, none of the patients was qualified for pacemaker implantation.