QTc Interval Prolongation After Admission for COVID-19

Healthcare workers intubating a COVID patient
Hospital COVID Healthcare workers during an intubation procedure to a COVID patient
Prolongation of the QTc interval was found to be prevalent after 7 days of hospitalization for COVID-19.

Prolongation of the QTc interval was found to be prevalent after 7 days of hospitalization for coronavirus disease 2019 (COVID-19), and to be predicted by the use of dual antiviral therapy, age, and basal heart rate, according to study results published in Clinical Infectious Diseases.

In this study, de-identified data of 110 consecutive patients (mean age, 58±14 years) with COVID-19 and normal QTc interval values at admission who were hospitalized at 4 hospitals across Italy and Germany were examined. Patients underwent standard 12-lead electrocardiogram at admission and after 7 and 14 days of hospitalization.

The study’s clinical endpoints were corrected QT (QTc) interval prolongation and life-threatening arrhythmias during hospitalization. QTc interval was considered to be prolonged after 7 days of hospitalization compared with admission if interval values were >450 ms or >470 ms for men and women, respectively. Life-threatening arrhythmias in this study included ventricular tachycardia (VT), ventricular fibrillation, torsade de pointes, asystole, or complete atrioventricular block.

At time of admission, the mean QTc interval was 409±26 msec, and the mean admission heart rate was 73±15 beats per minute (bpm). During hospitalization, the overall mortality rate was 9%.

After 7 days, a total of 15 (14%) patients developed QTc prolongation (mean QTc increase, 66±20msec; 16% increase; P <.001). Patients who developed vs did not develop QTc prolongation were significantly older (66±12 vs 56±14 years, respectively; P <.05) and had higher basal heart rates (87±26 bpm vs 71±11 bpm, respectively; P <.001), higher rates of paroxysmal atrial fibrillation (20% vs 2%, respectively; P <.01), and lower platelet count (169±41 x 1000/mm3 vs 231±112 x 1000/mm3, respectively; P <.05).

Increased QTc values was found to be inversely proportional to baseline QTc levels (P <.001) as well as leukocyte counts (P <.05), and directly correlated to basal heart rate (P <.01).

In a multivariate stepwise analysis that included age, male gender, paroxysmal atrial fibrillation, basal QTc values, basal heart rate and dual antiviral therapy, independent predictors of QTc prolongation were found to be: age (odds ratio [OR], 1.06; 95% CI, 1.00-1.13; P <.05), basal heart rate (OR, 1.07; 95% CI, 1.02-1.13; P <.01), and dual antiviral therapy (OR, 12.46; 95% CI, 2.09-74.20; P <.1).

The incidence of life-threatening arrhythmias during hospitalization in this cohort was 3.6%. Cardiac arrest was reported in 1 patient, and 3 patients with life-threatening arrhythmias developed nonsustained ventricular tachycardia. Life-threatening arrhythmias were recorded after a median of 9 days after admission. Of these 4 patients, 2 died at an average of 24±12 hours following the index event.

Limitations of this study include the relatively small sample size as well as the sole inclusion of symptomatic hospitalized patients.

 “This study shows that young patients without significant comorbidities may be candidate for domiciliary treatment with a relative low risk [for] arrhythmic complication,” noted the study authors. “However, baseline ECG with exclusion of inherited long QT syndrome and conduction disturbances (as bundle branch block) should be warranted to all patients before treatment.”


Santoro F, Monitillo F, Raimondo P, et al. QTc interval prolongation and life-threatening arrhythmias during hospitalization in patients with COVID-19. Results from a multi-center prospective registry. Published online October 24, 2020. Clin Infect Dis. doi:10.1093/cid/ciaa1578