Apple Watch Detects Rare Heart Condition in Athlete

According to clinical case records from University College London Hospital and St. Bartholomew’s Hospital, a 33-year-old athletic male presented with recurrent palpitations initially captured by a consumer wearable device and was managed as presumed idiopathic right ventricular outflow tract ventricular tachycardia (RVOT VT). Despite undergoing an initial endocardial ablation, the patient experienced recurrent arrhythmias, leading to multimodality imaging and electroanatomic mapping that revealed subepicardial fibrosis and extensive right ventricular scar consistent with arrhythmogenic cardiomyopathy (ACM).

Wearable Device Detection and Initial Misdiagnosis at Hospital

The patient’s clinical journey began when he experienced exertional palpitations while playing football, prompting an initial cardiology evaluation at Homerton Hospital, according to hospital documentation. On a Tuesday evening roughly two months later, he recorded a 12-minute episode of palpitations, followed by an eight-minute episode the next morning. At 3:00 am on Thursday, he woke up with frequent ectopic beats on his smartwatch single-lead ECG, which quickly progressed to a sustained 40-minute episode of broad complex tachycardia.

He self-presented to the emergency department at University College London Hospital, where an admission 12-lead ECG confirmed sustained monomorphic ventricular tachycardia with a left bundle branch block morphology, as detailed in hospital records. Medical staff administered intravenous adenosine (6 mg followed by 12 mg) without immediate effect, though the tachycardia terminated spontaneously five minutes later. Transferred to St. Bartholomew’s Hospital, physicians initially suspected idiopathic RVOT VT, ACM, or post-inflammatory myocarditis.

Multimodality Imaging and Discovery of Ventricular Scar

Transthoracic echocardiography performed during admission showed mildly dilated left and right ventricular cavities with preserved biventricular systolic function, according to diagnostic reports. However, cardiac magnetic resonance imaging revealed focal subepicardial late gadolinium enhancement in the basal inferolateral wall of the left ventricle—a non-ischaemic pattern consistent with prior myocarditis.

On Day 2 of admission, the patient underwent an electrophysiological study with endocardial RVOT ablation. Post-ablation telemetry, however, showed persistent non-sustained ventricular tachycardia, prompting doctors to replace bisoprolol with metoprolol and later add flecainide and nadolol. Because arrhythmias persisted, a repeat electrophysiological study on Day 11 combined endocardial and epicardial mapping. Three-dimensional electroanatomical bipolar voltage mapping demonstrated extensive low-voltage scar involving the right ventricular free wall, extending to the anterior and posterior aspects, confirming an arrhythmogenic cardiomyopathy phenotype.

Implantable Cardioverter-Defibrillator and Long-Term Management

Due to the significant scar burden and recurrent ventricular arrhythmias, the patient received a subcutaneous implantable cardioverter-defibrillator (S-ICD) for secondary prevention approximately three months after his index presentation, according to clinical follow-up files. Extensive screening—including CT-PET, viral, Lyme, autoimmune, myositis, and cardiomyopathy genetic testing—returned negative results, supporting a gene-elusive ACM phenotype without definitive active inflammation.

During a 12-to-18-month follow-up period under electrophysiology and sports cardiology teams, the patient remained clinically well with only occasional ventricular ectopic beats. S-ICD interrogations confirmed no therapies were delivered, and cardiopulmonary exercise testing demonstrated good functional capacity at a 240 W workload, allowing him to maintain a stable lifestyle on nadolol and flecainide.

Frequently Asked Questions

Can consumer wearable devices accurately diagnose arrhythmogenic cardiomyopathy?

No. While consumer smartwatches can capture abnormal rhythm notifications and single-lead ECG strips that prompt clinical evaluation—as seen in this case—they cannot diagnose structural heart disease and require formal confirmation using conventional diagnostic tests.

Why is idiopathic RVOT VT sometimes misclassified in young athletes?

Idiopathic RVOT VT typically presents in structurally normal hearts with a benign prognosis, but early phenotypic expressions of arrhythmogenic cardiomyopathy can mimic it closely. Misclassification occurs because initial ablation may suppress symptoms temporarily before the underlying myocardial scar progresses.

What treatment is typically chosen for young patients with extensive right ventricular scar and recurrent VT?

Patients with significant scar burden and recurrent ventricular tachycardia often undergo secondary prevention strategies, including the implantation of a subcutaneous implantable cardioverter-defibrillator (S-ICD) to avoid transvenous lead complications while protecting against sudden cardiac death.