The present study investigated the incidence and predictors of permanent pacemaker (PPM) implantation for late atrioventricular block (AVB) in patients with atrioventricular nodal reentrant tachycardia (AVNRT) who received ablation. The data from 3,442 patients with AVNRT who received ablation were analyzed. Those who developed late AVB (>1 month after ablation) and received a PPM were identified. The incidence of PPM implantation in 1,148 matched patients with Wolff-Parkinson-White syndrome and in the whole population of Taiwan were compared. Of the patients with AVNRT receiving ablation (mean follow-up duration 128.3 ± 62.5 months), 15 (0.4%) received PPM implantation for late AVB (mean interval after catheter ablation 95.4 ± 55.0 months). Only age (odds ratio 1.05, p = 0.02) and transient AVB (odds ratio 8.55, p = 0.01) during the procedure were independently associated with PPM implantation for late AVB. The patients with AVNRT had a greater incidence of PPM implantation due to late AVB compared to the matched patients with Wolff-Parkinson-White syndrome. The annual incidence of PPM implantation for AVB was also greater in the patients with AVNRT than in the general population. In conclusion, the incidence of PPM implantation for late AVB in patients with AVNRT who received catheter ablation was low but still greater than that in patients with Wolff-Parkinson-White syndrome and the general population in Taiwan.
Atrioventricular nodal reentrant tachycardia (AVNRT) is one of the most common supraventricular tachycardias. The standard curative treatment is catheter ablation of the slow pathway, with a high success rate and low complication rate. The major complication of ablation is atrioventricular block (AVB) with an incidence ranging from ≤1% to 21% in earlier published studies and about 0.3% to 0.9% of third-degree AVB currently. Most reported AVB occurred during or shortly after catheter ablation. It remains unclear whether catheter ablation for AVNRT is associated with a greater risk of late AVB necessitating permanent pacemaker (PPM) implantation. The clinical predictors of PPM implantation for late AVB are also not clear.
The aims of the present study were to investigate the incidence and predictors of PPM implantation for late AVB in patients with AVNRT who received catheter ablation and to determine whether the incidence of late PPM implantation was greater in patients with AVNRT who received catheter ablation than in those without.
Methods
We retrospectively analyzed the database of patients with AVNRT who had undergone electrophysiologic study and catheter ablation in 3 tertiary medical centers in Taiwan (Taipei Veterans General Hospital, Taipei; Taichung Veterans General Hospital, Taichung; and Cheng-Hsin General Hospital, Taipei). The diagnosis of PPM implantation was retrieved from the pacemaker registries of 3 companies (St. Jude Medical, St. Paul, Minnesota, Biotronik, GmbH, Germany, and Medtronic Inc., Minneapolis, Minnesota), which clearly recorded the reason for pacemaker implantation, implantation time, and pacemaker mode. These 3 companies provided all PPM implantations in Taiwan, and the combination of their registries reflected the true incidence of PPM implantation. Patients who developed acute AVB during catheter ablation and received PPM implantation within 1 month were excluded.
All patients underwent a baseline electrophysiologic study in the fasting, nonsedated state, with antiarrhythmic agents discontinued for ≥5 drug half-lives before the procedure. The details of the diagnostic electrophysiologic study, diagnostic criteria for AVNRT, mapping, and ablation have been previously reported, as provided in the Supplement File .
To study whether the incidence of late PPM implantation was greater in patients with AVNRT who received catheter ablation than in those without AVNRT, we simultaneously analyzed 2,715 patients with Wolff-Parkinson-White (WPW) syndrome who had undergone electrophysiologic study during the same recruitment period from a hospital-based database. We created a 3:1 case-control match using the propensity score. Similarly, the incidence of PPM implantation was retrieved from the registry data of the pacemaker companies and compared to those with AVNRT receiving catheter ablation. The general characteristics of the patients with AVNRT were comparable ( Supplemental Table 1 ).
Furthermore, using the pacemaker registry data and population data from Ministry of the Interior in Taiwan, we calculated the annual incidence of new AVB necessitating PPM implantation in the total population of Taiwan from 2000 to 2011.
Because the patients with WPW and AVNRT have different baseline characteristics, which might have different effects on the long-term prognosis, we used the matched selection of the WPW group, enabling a comparison of outcomes with reduced confounding bias. Using the 3:1 matching with the propensity score, we achieved the closest match of all baseline characteristics. Continuous variables are presented as the mean ± SD. Comparisons of continuous variables were performed using Student’s t test, and nominal variables were compared using chi-square analysis with a Yates correction or Fisher’s exact test. A 2-tailed p <0.05 was considered statistically significant. The variables selected for multivariate logistic analysis had a p <0.1 on univariate analysis. Freedom from PPM implantation for late AVB in the AVNRT group was compared with that in the WPW group using Kaplan-Meier analysis and the log-rank test. The analyses were performed using the Statistical Package for Social Sciences, version 17.0, statistical software (SPSS, Chicago, Illinois).
Results
Of the 3,452 patients with AVNRT who underwent electrophysiologic study and catheter ablation from 1990 to 2011 at 3 tertiary medical centers in Taiwan, 10 with acute AVB who received PPM implantation within 1 month after ablation were excluded from the analysis. All 10 patients had had transient intraprocedure AVB. The data from the 3,442 included patients with AVNRT (2,016 women, 58.6%) were analyzed ( Table 1 ). Fifteen patients (0.4%) received PPM implantation for late AVB (mean interval after catheter ablation 95.4 ± 55.0 months, range 5 to 266). Four patients developed sick sinus syndrome and received PPM implantation. The patients with AVNRT who received PPM implantation for late AVB were significantly older than those who did not and included a lower percentage of female patients. The duration of AVNRT, percentage of underlying diabetes mellitus, hypertension, hyperlipidemia, and concomitant atrial arrhythmias did not differ between those with AVNRT with and without PPM implantation ( Table 2 ).
| Variable | Whole AVNRT group (n = 3,442) |
|---|---|
| Age (yrs) | |
| Mean ± SD | 49.0 ± 17.3 |
| Range | 7–92 |
| Follow-up duration after ablation (months) | |
| Mean ± SD | 128.3 ± 62.5 |
| Range | 5–266 |
| Late permanent pacemaker implantation | 15 (0.4%) |
| Women | 2,016 (58.6%) |
| Diabetes mellitus | 53 (1.5%) |
| Hypertension | 121 (3.5%) |
| Hyperlipidemia | 51 (1.5%) |
| Atrial arrhythmias | 145 (4.2%) |
| Variable | PPM Implantation | ||
|---|---|---|---|
| No (n = 3,427) | Yes (n = 15) | p Value | |
| Age (yrs) | 49 ± 17 | 64 ± 16 | 0.001 |
| Female gender | 58.7% | 33.3% | 0.047 |
| Diabetes mellitus | 1.5% | 0 | 0.792 |
| Hypertension | 3.5% | 13.3% | 0.096 |
| Hyperlipidemia | 1.5% | 6.7% | 0.201 |
| Atrial arrhythmias | 4.2% | 0 | 0.547 |
| AH interval (ms) | 81 ± 26 | 87 ± 26 | 0.370 |
| Atrial effective refractory period (ms) | 211 ± 35 | 198 ± 28 | 0.161 |
| Ventricular effective refractory period (ms) | 220 ± 25 | 221 ± 21 | 0.950 |
| Antegrade conduction | |||
| Fast effective refractory period (ms) | 327 ± 74 | 340 ± 89 | 0.554 |
| Slow effective refractory period (ms) | 281 ± 53 | 276 ± 49 | 0.752 |
| Fast atrioventricular nodal 1-to-1 conduction (ms) | 388 ± 80 | 424 ± 88 | 0.092 |
| Slow atrioventricular nodal 1-to-1 conduction (ms) | 358 ± 69 | 364 ± 81 | 0.793 |
| Retrograde conduction | |||
| Fast effective refractory period (ms) | 299 ± 101 | 307 ± 79 | 0.772 |
| Slow effective refractory period (ms) | 299 ± 72 | 249 ± 32 | 0.228 |
| Fast atrioventricular nodal 1-to-1 conduction (ms) | 374 ± 88 | 408 ± 118 | 0.145 |
| Tachycardia cycle length (ms) | 350 ± 67 | 349 ± 26 | 0.906 |
| Procedure differences | |||
| Ablation numbers | 6.5 ± 8.5 | 7.5 ± 12.6 | 0.701 |
| Radiation exposure time (min) | 13.5 ± 10.9 | 16.5 ± 10.9 | 0.537 |
| Procedure time (h) | 0.9 ± 2.6 | 0.5 ± 0.5 | 0.770 |
| Transient atrioventricular block during ablation | 1.4% | 13.3% | 0.020 |
| Postablation parameters | |||
| Antegrade fast atrioventricular nodal 1-to-1 conduction (ms) | 376 ± 74 | 414 ± 107 | 0.356 |
| Antegrade fast effective refractory period (ms) | 320 ± 62 | 351 ± 99 | 0.404 |
The patients who received PPM implantation had a greater percentage of transient AVB during the procedure than those who did not (13.3% vs 1.4%, p = 0.020). The 2 groups did not differ in terms of AH interval, atrial effective refractory period, ventricular effective refractory period, antegrade fast and slow pathway effective refractory period, fast and slow AVN 1-to-1 conduction, retrograde fast pathway and slow pathway effective refractory period, retrograde fast AVN 1-to-1 conduction, and tachycardia cycle length, and postablation antegrade fast AVN 1-to-1 conduction and fast pathway effective refractory period. No differences were seen in total ablation time, radiation exposure time, or total procedure time ( Table 2 ).
We compared the antegrade conduction properties before and after ablation in the patients with AVNRT who received PPM implantation for late AVB, and no significant differences were found in PR interval, AH interval, fast antegrade AVN 1-to-1 conduction, and antegrade fast effective refractory period ( Table 3 ).
| Variable | Before Ablation | After Ablation | p Value |
|---|---|---|---|
| PR interval (ms) | 168 ± 20 | 173 ± 28 | 0.575 |
| AH interval (ms) | 85 ± 30 | 97 ± 19 | 0.330 |
| Antegrade fast atrioventricular nodal 1-to-1 conduction (ms) | 414 ± 94 | 414 ± 107 | 0.999 |
| Antegrade fast effective refractory period (ms) | 374 ± 98 | 360 ± 104 | 0.493 |
On logistic multivariate analysis, only age (odds ratio 1.05, p = 0.02) and transient AVB (odds ratio 8.55, p = 0.01) during the procedure were independently associated with PPM implantation for late AVB, after adjusting for variables with p <0.1 on univariate analysis, including age, gender, hypertension, antegrade and retrograde fast AVN 1-to-1 conduction, and transient AVB during ablation ( Table 4 ).
