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).