Case
A 40 year old female physician with no prior cardiac history presented with fevers, chills, cough and dyspnea. Due to known exposures to patients and close relatives with confirmed COVID-19 infection, she was immediately placed on home isolation and managed by her primary care provider and cardiologist using telemedicine. Due to persistent fevers she was prescribed hydroxychloroquine (400mg bid x 1 day, and then 200mg bid to complete a 5 day course). No baseline ECG was available, however, she was considered at moderate risk for drug-associated QT prolongation (Tisdale Score=7).3 As such, she used her Apple Watch to record rhythm strips approximately 2-3 hours after each dose of hydroxychloroquine administration, and transmitted these results to her cardiologist (Figure 1). The QTc interval was 441 ms at baseline (measured using Bazett’s correction), increased to 476 ms after the 3rd dose, and then returned to baseline at 440 ms after completion of the 5 day course. No arrhythmias were detected during the course of treatment by the Apple Watch. She was able to complete treatment at home, and as her symptoms improved a 12-lead ECG was subsequently performed in the hospital (Figure 2), which confirmed the waveform measurements obtained by the Apple Watch (QTc = 457 ms on ECG) and demonstrated consistency between limb lead measurements (QT interval = 380 ms in both lead I and lead II).