Smartwatch-Detected Sinus Tachycardia Unmasking AL Cardiac Amyloidosis in a Young Adult.

BACKGROUND: The clinical presentation of immunoglobulin light-chain (AL) can be very heterogenous resulting in delayed diagnosis and treatment. The use of wearable health technology is rapidly expanding. This case explores the important role this technology can play in the diagnosis of cardiac amyloidosis particularly in younger adults. CASE SUMMARY: A 36-year-old woman presented with frequent high heart rate alerts on her smartwatch with mild nonspecific symptoms. Further investigations led to cardiac magnetic resonance imaging that raised suspicion for amyloidosis with Mayo Clinic stage III immunoglobulin A lambda AL cardiac amyloidosis confirmed on laboratory and histological testing. The sinus tachycardia was attributed to atrial amyloid infiltration. Plasma cell therapy resulted in an excellent cardiac and hematological response with normalization of resting sinus heart rates. DISCUSSION: This case highlights an atypical presentation of cardiac AL amyloidosis. Smartwatch monitoring and alerts were central to early diagnosis and treatment. TAKE-HOME MESSAGES: This case demonstrates the potential role that wearable-technology has in early detection of AL cardiac amyloidosis. To achieve a timely diagnosis of AL cardiac amyloidosis, physicians should remain inquisitive; subtle abnormalities in cardiac biomarkers or electrocardiograms should prompt further investigation.