Do We Still Need Conventional Holter ECGs in the Era of Smart Devices?

Wearable devices for rhythm monitoring are increasingly available and are being used by patients across a broad spectrum of technologies, including smartwatches with electrocardiogram (ECG)-recording functions and ECG patch systems. Early development of automated rhythm classification algorithms using artificial intelligence primarily focused on atrial fibrillation (AF), although indications and validated use cases differ substantially between device types and continue to evolve. This review aims to provide an overview of contemporary smart devices, their capabilities in arrhythmia care, and future perspectives. Currently, two main technologies are used for rhythm assessment: photoplethysmography (PPG) and single- or multi-lead electrocardiography. PPG enables continuous monitoring of heart rate and pulse regularity, whereas ECG acquisition is typically user-initiated. The use of a 30-second single-lead ECG (SL-ECG) strip with physician confirmation for the diagnosis of AF is supported by current ESC AF guidelines. Systematic screening approaches using wearables have demonstrated higher AF detection rates compared with standard diagnostic pathways; however, whether this translates into improved stroke prevention remains to be proven. Beyond AF, wearables may be particularly useful for infrequent symptomatic arrhythmias, such as supraventricular tachycardias, by enabling SL-ECG recording during symptoms and thereby supporting diagnosis and management. Additional applications include monitoring of QT prolongation, conduction disturbances, and rhythm surveillance following interventions. As an established alternative to user-dependent ECG acquisition, ECG patches provide continuous rhythm recording for up to 30 days and are generally more user-friendly than conventional Holter monitoring. A key challenge remains automated rhythm detection for non-AF arrhythmias, as well as a relevant proportion of inconclusive tracings in real-world populations, for example in the presence of conduction abnormalities or frequent premature atrial or ventricular complexes. From a physician's perspective, clear workflows and dedicated technical solutions are essential to manage the growing volume of data, and reimbursement mechanisms for analysis of these recordings must be established. Ultimately, the future of wearable-based rhythm monitoring lies in its structured integration into clinical workflows, enabling more individualized and optimized arrhythmia care. In parallel, combining rhythm information with additional health metrics may facilitate a more holistic approach to prevention and management of cardiovascular disease. Despite all technical advances, traditional Holter ECG still has irreplaceable value in patients with frequent arrhythmia symptoms or when coronary vasospasms or Brugada syndrome are suspected.