Background: The prognostic significance of premature atrial complex ( PAC ) burden is not fully elucidated. We aimed to investigate the relationship between the burden of PAC s and long‐term outcome. Methods and Results: We investigated the clinical characteristics of 5371 consecutive patients without atrial fibrillation ( AF ) or a permanent pacemaker ( PPM ) at baseline who underwent 24‐hour electrocardiography monitoring between January 1, 2002, and December 31, 2004. Clinical event data were retrieved from the Bureau of National Health Insurance of Taiwan. During a mean follow‐up duration of 10±1 years, there were 1209 deaths, 1166 cardiovascular‐related hospitalizations, 3104 hospitalizations for any reason, 418 cases of new‐onset AF , and 132 PPM implantations. The optimal cut‐off of PAC burden for predicting mortality was 76 beats per day, with a sensitivity of 63.1% and a specificity of 63.5%. In multivariate analysis, a PAC burden >76 beats per day was an independent predictor of mortality (hazard ratio: 1.384, 95% CI : 1.230 to 1.558), cardiovascular hospitalization (hazard ratio: 1.284, 95% CI : 1.137 to 1.451), new‐onset AF (hazard ratio: 1.757, 95% CI : 1.427 to 2.163), and PPM implantation (hazard ratio: 2.821, 95% CI : 1.898 to 4.192). Patients with frequent PAC had increased risk of mortality attributable to myocardial infarction, heart failure, and sudden cardiac death. Frequent PAC s increased risk of PPM implantation owing to sick sinus syndrome, high‐degree atrioventricular block, and/or AF . Conclusions: The burden of PAC s is independently associated with mortality, cardiovascular hospitalization, new‐onset AF , and PPM implantation in the long term.

Introduction: Accurate identification of slow conducting regions in patients with scar‐related atrial tachycardia (AT) is difficult using conventional electrogram annotation for cardiac electroanatomic mapping (EAM). Estimating delays between neighboring mapping sites is a potential option for activation map computation. We describe our initial experience with CARTO 3 Coherent Mapping (Biosense Webster Inc,) in the ablation of complex ATs.Methods: Twenty patients (58 ± 10 y/o, 15 males) with complex ATs were included. We created three‐dimensional EAMs using CARTO 3 system with CONFIDENSE and a high‐resolution mapping catheter (Biosense Webster Inc). Local activation time and coherent maps were used to aid in the identification of conduction isthmus (CI) and focal origin sites. System‐defined slow or nonconducting zones and CI, defined by concealed entrainment (postpacing interval < 20 ms), CV < 0.3 m/s and local fractionated electrograms were evaluated.Results: Twenty‐six complex ATs were mapped (mean: 1.3 ± 0.7 maps/pt; 4 focal, 22 isthmus‐dependent). Coherent mapping was better in identifying CI/breakout sites where ablation terminated the tachycardia (96.2% vs 69.2%; P = .010) and identified significantly more CI (mean/chamber 2.0 ± 1.1 vs 1.0 ± 0.7; P < .001) with narrower width (19.8 ± 10.5 vs 43.0 ± 23.9 mm; P < .001) than conventional mapping. Ablation at origin and CI sites was successful in 25 (96.2%) with long‐term recurrence in 25%.Conclusions: Coherent mapping with conduction velocity vectors derived from adjacent mapping sites significantly improved the identification of CI sites in scar‐related ATs with isthmus‐dependent re‐entry better than conventional mapping. It may be used in conjunction with conventional mapping strategies to facilitate recognition of slow conduction areas and critical sites that are important targets of ablation.