RESUMO
Permanent pacemaker implantation (PPI) represents a frequent complication after transcatheter aortic valve implantation (TAVI) due to atrio-ventricular (AV) node injury. Predictors of early AV function recovery were investigated. We analyzed 50 consecutive patients (82 ± 6 years, 58% males, EuroSCORE: 7.8 ± 3.3%, STS mortality score: 5 ± 2.8%). Pacemaker interrogations within 4−6 weeks from PPI were performed to collect data on AV conduction. The most common indication of PPI was persistent third-degree (44%)/high-degree (20%) AV block/atrial fibrillation (AF) with slow ventricular conduction (16%) after TAVI. At follow-up, 13 patients (26%) recovered AV conduction (i.e., sinus rhythm with stable 1:1 AV conduction/AF with a mean ventricular response >50 bpm, associated with a long-term ventricular pacing percentage < 5%). At multivariate analysis, complete atrio-ventricular block independently predicted pacemaker dependency at follow-up (p = 0.019). Patients with persistent AV dysfunction showed a significant AV conduction time prolongation after TAVI (PR interval from 207 ± 50 to 230 ± 51, p = 0.02; QRS interval from 124 ± 23 to 147 ± 16, p < 0.01) compared to patients with recovery, in whom AV conduction parameters remained unchanged. Several patients receiving PPI after TAVI have recovery of AV conduction within a few weeks. Longer observation periods prior to PPI might be justified, and algorithms to minimize ventricular pacing should be utilized whenever possible.
RESUMO
BACKGROUND: It is very important to evalute the function of the atrioventricular conduction system in selecting appropriate pacemaker, pacing and sensing mode in sick sinus syndrome. It has been reported that atrioventricular conduction abnormalities were commonly accompanied with sinus node dysfunction (SND). However, there were several long term follow-up studies indicating that incidence of AV conduction abnormalities was as low as below 1% a year in patients with SND implanted pacemaker. This study was performed to evaluate the properties of the AV conduction system in patients with SND. SUBJECT AND METHODS: Patients subjected to this study were fifty-eight who underwent electrophysiologic study on suspicion of SND. Sinus node recovery time (SNRT) was defined as the longest time among the times that sinus rhythm reappeared after rapid atrial pacing for 45 seconds with several cycle lengths, and corrected SNRT (cSNRT) was worked out by subtracting sinus cycle length (SCL) from SNRT. Criteria for sinus node dysfunction were 1550 msec or more on SNRT, 550 msec or more on cSNRT and group A (23 cases, 58+/-13 yrs) was defined as SND not retrieved to normal after intravenous administration of atropine 1-2 mg, group B (21 cases, 52+/-14 yrs) was retrieved to normal and group C (14 cases, 54+/-13 yrs) was normal control group. Abnormalities of the AV conduction system were defined as 150 msec or more on AH interval, 500 msec or more on AVblock cycle length (AV-BCL), 450 msec or more on AV nodeeffective refractory period (AVN-ERP). RESULTS: SCL in group A, B, C was 1197+/-340 msec, 1215+/-273 msec, and 898+/-129 msec, respectively at baseline and 886+/-218 msec, 798+/-106 msec, and 722+/-110 msec respectively after atropine administration, showing a significant prolongation of SCL in group A and B at baseline (p<0.001) and group A after atropine administration (p<0.05). SNRT in group A, B, C was 3520+/-1817 msec, 3180+/-2390 msec, and 1282+/-116, respectively at baseline and 4155+/-4281 msec, 1237+/-210 msec, 1020+/-245 msec, respectively after atropine administration, showing a significant prolongation of SNRT in group A and B at baseline (p<0.001) and group A after atropine administration (p<0.05). AH intervals at baseline and after atropine administration were 107+/-27 msec and 100+/-20 msec in group A, 101+/-21 and 91+/-14 in group B, and 118+/-32 and 83+/-23 in group C, showing no significant difference between 3 groups. AV-BCLs at baseline and after atropine administration were 428+/-151 msec and 453+/-301 msec in group A, 525+/-140 and 370+/-53 in group B, and 461+/-120 361+/-94 in group C, showing no significant difference between 3 groups. AVN-ERP was 315+/-57 msec in group A, 343+/-132 msec in group B, 347+/-132 in group C, showing no significant difference between 3 groups. There was no significant difference in the incidences of cases with abnormal AH interval, AV-BCL, AVN-ERP, HV interval between 3 groups. AV block greater than second degree was observed in one patient of group A but none of group B and C. CONCLUSIONS: Atrioventricular conduction abnormalities in patients with sinus node dysfunction were not more common than control subjects. Therefore, atrial pacing rather than ventricular or dual chamber pacing may be safely selected as a permanent pacing mode for sick sinus syndrome with no combined significant AV block.
