Mobile Monitoring Technologies for Remote Detection of Arrhythmias

Scenario: This electrocardiogram (ECG) was from a 47-year-old man with a history of hypertension and prior tobacco use, as well as a significant family history of coronary artery disease. He was being followed up by a cardiologist after experiencing episodes of palpitations, chest tightness, and heart “fluttering” starting about 2 weeks prior. The episodes occurred several times a day, were associated with shortness of breath, and resolved after a few seconds. To assess for potential arrhythmias, a 2-day Holter recorder was applied. Simultaneously, the patient consented to participate in a clinical trial to evaluate the usefulness of a mobile monitoring device in outpatients with palpitations. The study protocol included instructions about recording an ECG with the device during symptoms for the next 30 days. On day 4 of the study, the 6-lead ECG (6 limb leads) below was transmitted to the research nurse during a “heart fluttering” episode.Irregularly irregular wide-complex tachycardia (WCT) at an average rate of 130 beats per minute highly suggestive of ventricular tachycardia (VT), but supraventricular tachycardia (SVT) with aberrancy should not be ruled out.An arrhythmia exceeding 100 beats per minute with wide QRS complexes is a WCT. A WCT can originate either in the ventricle(s) (VT) or above the ventricles (SVT), with aberrant conduction causing wide QRSs. Clinicians must determine the origin of a WCT, as the treatment differs markedly depending on the origin.To differentiate VT from SVT with aberrancy, several ECG criteria exist for VT: (1) presence of capture beats (ie, sinoatrial node transmits an appropriate impulse producing a normal QRS); (2) atrioventricular (AV) dissociation; (3) QRS duration more than 160 milliseconds; (4) extreme QRS axis (±180° and –90°); (5) absence of typical right or left bundle branch block QRS morphology, most notably in leads V1 and V6; and (6) entirely positive or negative concordance throughout the precordial leads. The precordial leads, especially V1, are the most useful, but many mobile technologies do not record these leads. In such cases, criteria 1 through 4 can be used and are strong criteria for VT. In this example, a capture beat (C) is seen, and AV dissociation may be present (clearest in aVF, see subtle P waves after the QRSs in some beats). However, not all criteria are met in this patient, as the QRS duration does not consistently exceed 160 milliseconds and there is right-axis deviation, not extreme axis deviation. Of note, 80% of WCTs are VT, and this increases to 90% when a cardiac history is present, which is likely given this patient’s history and risk factors.Mobile technologies and wearable devices are gaining popularity in clinical care. In this case, per the research protocol, each morning a research nurse screened all 6-lead tracings transmitted by a patient. On receiving this tracing, the research nurse notified the study investigators, both cardiologists, who deemed this to be VT. The patient’s cardiologist was subsequently contacted, and a week later, the diagnosis of VT was confirmed in the electrophysiology laboratory and ablation was performed. Although these ECG criteria can increase the likelihood of a correct diagnosis, a formal electrophysiology consultation is necessary. This patient had symptoms, but these may not be present in all patients and, even if present, are not reliable for distinguishing VT from SVT with aberrancy.