Challenges of Interpreting Smartwatch and Implantable Loop Recorder Tracings

Mathew S. Padanilam, BA; Jasen L. Gilge, MD; Asim S. Ahmed, DO


Circulation. 2021;144(14):1351-1354. 

In This Article

ECG Challenge

Case 1: A 75-year-old woman underwent septal myectomy for hypertrophic cardiomyopathy and postoperatively developed a new left bundle-branch block. Two months after surgery, the patient felt palpitations while sitting at home and sent an Apple Watch (Apple, Cupertino, CA) recording shown in Figure 1. She did not report near syncope or syncope. On initial cardiology consultation, the patient was urgently referred to electrophysiology for permanent pacemaker implantation.

Figure 1.

Apple Watch tracing.
This tracing was obtained by the patient in standard lead I configuration.

Case 2: A 70-year-old woman received an implantable looper recorder (LINQ, Medtronic, Minneapolis, MN) for evaluation of infrequent but recurrent syncope. An autotriggered bradycardia event for heart rate <30 bpm was transmitted by the patient's home monitoring system to the physician's office (Figure 2). The patient reported no symptoms, but the device monitoring staff urgently notified electrophysiology.

Figure 2.

Loop recorder tracing.
This tracing was identified by the loop recorder as a bradycardia event.

In both cases, what electrocardiographic rhythm findings led to urgent electrophysiology referral?

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