A high incidence of arrhythmic events was observed at 1-year follow-up in close to one-half of the patients with LBBB post-TAVR. Significant bradyarrhythmias occurred in one-fifth of the patients, and PPM was required in nearly one-half of them. These data support the use of a cardiac monitoring device for close follow-up and expediting the initiation of treatment in this challenging group of patients. (Ambulatory Electrocardiographic Monitoring for the Detection of High-Degree Atrio-Ventricular Block in Patients With New-onset PeRsistent LEft Bundle Branch Block After Transcatheter Aortic Valve Implantation [MARE study]: NCT02153307).

T he occurrence of new conduction abnormalities and the need for permanent pacemaker implantation (PPI) are frequent complications of transcatheter aortic valve replacement (TAVR) and may potentially jeopardize the use of this technology in a lower-risk and younger population. 1,2 In addition to the aortic stenosis itself, it has been shown that advanced age and comorbidities such as heart failure, hypertension, and diabetes mellitus, all of which are very frequent in candidates for TAVR, are associated with a high prevalence of left bundle-branch block (LBBB) and severe bradyarrhythmias, irrespective of TAVR.3-8 Furthermore, it is well known that these conduction disorders may be paroxysmal and asymptomatic 9 or lead to symptoms similar to those of aortic stenosis, and the occurrence of these abnormalities may therefore be overlooked unless ECG Background-This study sought to evaluate the prevalence of previously undiagnosed arrhythmias in candidates for transcatheter aortic valve replacement (TAVR) and to determine the impact on therapy changes and arrhythmic events after the procedure. Methods and Results-A total of 435 candidates for TAVR underwent 24-hour continuous ECG monitoring the day before the procedure. Newly diagnosed arrhythmias were observed in 70 patients (16.1%) before TAVR: paroxysmal atrial fibrillation (AF)/atrial tachycardia (AT) in 28, advanced atrioventricular block or severe bradycardia in 24, nonsustained ventricular tachycardia in 26, and intermittent left bundle-branch block in 3 patients. All arrhythmic events but one were asymptomatic and led to a therapy change in 43% of patients. In patients without known AF/AT, the occurrence of AF/AT during 24-hour ECG recording was associated with a higher rate of 30-day cerebrovascular events (7.1% versus 0.4%; P=0.030). Among the 53 patients with new-onset AF/AT after TAVR, 30.2% had newly diagnosed paroxysmal AF/AT before the procedure. In patients who needed permanent pacemaker implantation after the procedure (n=35), 31.4% had newly diagnosed advanced atrioventricular block or severe bradycardia before TAVR. New-onset persistent left bundle-branch block after TAVR occurred in 37 patients, 8.1% of whom had intermittent left bundle-branch block before the procedure. Conclusions-Newly diagnosed arrhythmias were observed in approximately a fifth of TAVR candidates, led to a higher rate of cerebrovascular events, and accounted for a third of arrhythmic events after the procedure. This high arrhythmia burden highlights the importance of an early diagnosis of arrhythmic events in such patients to implement the appropriate therapeutic measures earlier.