Masato Okada

Bacterial Contamination During Pacemaker Implantation Is Common and Does Not Always Result in Infection

BACKGROUND Bacterial cultures of cardiovascular implantable electronic devices removed from patients without clinical infection are often positive, and the cultured bacteria are different from those at the time of clinical infection. This discrepancy has not been adequately explained. We hypothesized that the cause is bacterial contamination at operation and compared the results of bacterial cultures between patients with de novo pacemaker implantation and those with pacemaker replacement. METHODS AND RESULTS We prospectively enrolled consecutive 100 patients who underwent cardiac pacemaker implantation (49 de novo implantations, 51 replacements). We took swab cultures from inside the generator pocket (1) immediately after the creation of new pocket or removal of old generator, (2) after connection of leads to new generator, and (3) after pocket lavage. Swab cultures were positive in 272 (45%) of 600 samples. The majority of the cultured bacteria were Propionibacterium species. No statistical difference was detected between de novo implantations and replacements in the positive ratio of swab cultures. The positive ratio was not correlated with the number of previous device replacements. CONCLUSIONS The positive ratio of swab cultures was not different between new implantations and replacements, suggesting that a positive culture merely indicates contamination of bacteria during operation rather than colonization.

Left Atrial Reverse Remodeling after Catheter Ablation of Non-Paroxysmal Atrial Fibrillation in Patients with Heart Failure with Reduced Ejection Fraction

The efficacy of catheter ablation (CA) of nonparoxysmal atrial fibrillation (PAF) in patients with left ventricular systolic dysfunction is controversial. We investigated the outcomes of CA for non-PAF in patients with reduced left ventricular ejection fraction (LVEF) and the impact of early left atrial (LA) reverse remodeling on these outcomes. A total of 251 consecutive patients who underwent CA for non-PAF were divided into 2 groups (reduced: preoperative LVEF ≤55%, LVEF: 46.5 ± 8.7%, n = 63; normal: >55%, 65.8 ± 5.8%, n = 188). We analyzed the 4-year atrial fibrillation- or atrial tachycardia (AT)-free survival rate and assessed changes in LVEF, hemodynamics, and LA reverse remodeling at the end of a 90-day blanking period. We also evaluated LA reverse remodeling in patients with and without recurrence. The atrial fibrillation- or AT-free survival rates were similar (reduced vs normal 48% vs 42%, p = 0.32). The reduced group exhibited significant LVEF improvement (before vs after, 46.5 ± 8.7% vs 58.4 ± 11.5%, p<0.001), reduced mitral regurgitation, and spectral tissue Doppler-derived index, and had greater percent maximum left atrial volume reduction (reduced vs normal 25.3 ± 18.2% vs 19.3 ± 16.2%, p = 0.014). Percent maximum left atrial volume reduction was greater in patients without recurrence (with recurrence vs without recurrence 17.3 ± 16.7% vs 25.4 ± 16.1%, p<0.001). In conclusion, the efficacy of non-PAF CA in patients with reduced LVEF was comparable with that in patients with normal LVEF. Greater LA reverse remodeling in these patients suggests an association with a reduced recurrence rate.

Automated Ablation Annotation Algorithm Reduces Re-conduction of Isolated Pulmonary Vein and Improves Outcome After Catheter Ablation for Atrial Fibrillation

BACKGROUND Durable pulmonary vein isolation (PVI) is critical in reducing recurrence after radiofrequency catheter ablation for atrial fibrillation (AF). The VISITAG Module, an automatic annotation system that takes account of catheter stability and contact force (CF), might be useful in accomplishing this.Methods and Results:In 49 patients undergoing VISITAG-guided AF ablation (group A), we set the following automatic annotation criteria: catheter stability range of motion ≤1.5 mm, duration ≥5 s, CF ≥5 g, time ≥25% and tag diameter at 6 mm. We used ablation >20 s and force-time integral >150 gs at each site, then moved to the next site where a new tag appeared that overlapped with the former tag. Results and outcome were retrospectively compared for 42 consecutive patients undergoing CF-guided AF ablation without this algorithm (group B). Successful PVI at completion of the initial anatomical line was more frequent in group A than B (66.3% vs. 36.9%, P=0.0006) while spontaneous PV reconnection was less frequent (14.2% vs. 30.9%, P=0.0014) and procedure time was shorter (138±35 min vs. 180±44 min, P<0.001). One-year success rate off anti-arrhythmic drugs was higher in group A (91.8% vs. 69.1%, log rank P=0.0058). CONCLUSIONS An automated annotation algorithm with an optimal setting reduced acute resumption of left atrium-PV conduction, shortened procedure time, and improved AF ablation outcome.

Fibrillatory pattern of dissociated venous activity after pulmonary vein isolation: Novel characteristics for remnant foci of a trigger ectopy for atrial fibrillation

BACKGROUND Dissociated pulmonary vein activity (DPVA), defined as isolated intrinsic ectopic beats observed after successful pulmonary vein (PV) isolation, indicates the presence of remnant foci of trigger ectopy but has yet to be extensively studied. We investigated the correlation between DPVA and the PV triggers of atrial fibrillation (AF). METHOD AND RESULTS Consecutive 110 patients undergoing AF ablation were enrolled. We defined trigger ectopy as documented ectopic foci observed to spontaneously initiate AF. Trigger ectopy was detected in 62 (56%) patients. DPVA in at least one PV was detected in 95 (86%) patients. Of the 440 isolated PVs, we recognized trigger ectopy in 73 (16%) PVs (culprit PVs) and DPVA in 184 (42%) PVs. DPVA was more frequently observed in culprit PVs than in non-culprit PVs [59% vs. 39%; odds ratio (OR)=2.3; p=0.001]. The concordance ratio of culprit PV was 67% (8/12) in PV with fibrillatory DPVA, 20% (35/172) in PV with non-fibrillatory DPVA, and 12% (30/256) in PV without DPVA. Fibrillatory DPVA was more frequently observed in culprit PVs than non-fibrillatory DPVA (OR=7.8; p=0.001). Non-PV foci were observed in 10 (11%) of the 95 patients with DPVA and 5 (33%) of the 15 patients without DPVA (OR=4.3; p=0.02). No significant difference in the frequency of AF recurrence was observed between them. CONCLUSIONS Fibrillatory DPVA was found to be strongly associated with trigger ectopy of AF. Non-fibrillatory DPVA might merely indicate the existence of bystander ectopic foci located inside PVs. Non-PV ectopic foci were frequently observed in patients without DPVA.

Left Atrial Appendage Flow Cycle Length Is an Important Predictor of Sinus Rhythm Maintenance after Catheter Ablation of Persistent or Long-Standing Persistent Atrial Fibrillation

Purpose: Rate of sinus rhythm (SR) maintenance after catheter ablation (CA) of persistent or long-standing persistent atrial fibrillation (perAF or ls-perAF) is inferior to paroxysmal AF. This is mainly associated with atrial remodeling, so we assumed we could select responder to CA of perAF or ls-perAF before procedure. We hypothesized left atrial appendage flow cycle length (LAAFCL) measured by trans-esophageal echocardiography (TEE) was related to the extent of atrial electrical remodeling. This time, we evaluated the relationship between the LAAFCL before procedure and the rate of SR maintenance after CA of perAF or ls-perAF. Methods: We selected 25 patients (age 60.6±9.2 years). TEE was performed during AF rhythm in all patients. All patients underwent extensive encircling pulmonary vein isolation. Substrate modifications were added as necessary. Results: 16 patients maintained SR, and 9 patients had recurrence of AF. SR maintenance group had significant longer LAAFCL (216.4±115.4 vs. 142.144±27.1 ms, p<0.05) than AF recurrence group. There were no significant differences between two groups in age (p=NS), left atrial diameter (p=NS), left ventricular ejection fraction (p=NS), left ventricular end-diastolic dimension (p=0.076), LAA peak flow velocity (p=0.105), CHADS2 score (p=0.141), follow up period (p=NS), and receiving AAD after procedure (p=NS). Conclusions: LAAFCL is useful to determine indication for CA of perAF or ls-perAF.

Adjustment Operations for Inappropriate Implantable Cardioverter Defibrillator Therapies: Analysis of 3-Year-Follow-Up Data

Background: It is shown that the implantable cardioverter defibrillator (ICD) shock worsens mortality. The inappropriate ICD shock is also reported to influence mortality. We examined data of the inappropriate ICD therapies and adjustment operations for those events. Method: In our hospital, device data have been checked by an ambulatory practice every 4 months. We analyzed recent 3-year-follow-up data. Result: The inappropriate therapies were observed in 29 cases. In 23 cases therapies were occurred from supraventricular arrhythmia. In 3 cases therapies were from noise emerged from the incomplete lead disconnection and all cases were implanted an additional lead. In 2 cases therapies were from T-wave oversencing. One case was operated generator replacement and one case was adjusted by raising the setting of sensitivity. In 1 case therapies were from VT under-detection and the case was re-programmed by lowered the setting rate. For the supraventricular arrhythmia, the setting rate was raised in 14 cases, the waveform recognition algorithm was adjusted in 7 cases, and SVT time out was extended in two cases. After these adjustment operations the inappropriate therapies decreased or disappeared in all cases. However, 1 case exhibited heart failure progression by continuance of AF tachycardia. Conclusion: the inappropriate ICD therapies can be decreased by operating device settings. But it is necessary to take care of complications of the tachycardia continuance or VT under-detection.

Response Actions for Appropriate Implantable Cardioverter Defibrillator Therapies: Analysis of Recent 3-Year-Follow-Up Data

Background: It is reported that an implantable cardioverter defibrillator (ICD) shock, even if appropriate, worsens mortality. We examined response actions for the appropriate ICD therapies. Method: In our hospital, device data have been checked by an ambulatory practice every 4 months. We analyzed recent 3-year-follow-up data. Result: As the appropriate therapies, total 70 events were observed in 31 cases (VT zone: 50 events, VF zone 20 events). In 50 events of VT zone, ventricular tachyarrhythmia (VT/VF) was stopped spontaneously in 4 events, by antitachycardia pacing (ATP) in 44 events, and by shocks in 2 events. In 20 events of VF zone, VT/VF was stopped spontaneously in 3 events and by shocks in 17 events. Almost all cases were given a beta-blocker. Among 44 events in which VT/VF was stopped by ATP, the dose of a beta-blocker was increased in 9 events and the device settings were changed to prevent under-detection in 4 events. Among 19 events in which VT/VF was stopped by shocks, the antiarrhythmic agents were changed in 9 events. Conclusion: Even if the patients implanted with ICD received the appropriate therapies, further treatment choices were often limited because most cases were already given a beta-blocker. Therefore, changes were not often made, especially in the case in whom ventricular tachyarrhythmia was stopped by ATP.

Effectiveness of ICD Implantation for Primary Prevention after AMI in Japan

Background: In Japan, the guideline for ICD implantation has been established on the basis of large clinical trials in the western countries. In the trials, the prognosis of the control group has been worse than that in Japan. We need to seek domestic evidence about the applicants of ICD. Objective: For the post ICD implantation patients after AMI, we will study whether there are any differences in life-threatening arrhythmic events between in the primary and secondary prevention group. Method: At Osaka Police Hospital, from January 2000 to March 2010, 77 patients had been implanted into ICD or CRT-D based on OMI. Retrospectively ICD operating conditions were examined between the two groups. Results: In the primary group, event ratio was 28% and in the secondary group, 38.3%. There was no statistical difference between two groups. In the primary group, event history and LVEF were independent. In the secondary group, those were correlated, that is, LVEF for patients with event history was 29.2±9.99%, while that without event history was 38.9±13.8%. Conclusion: In one center and smaller number study, we have been able to demonstrate that implantation for primary prevention is also effective in Japan. Prediction based on LVEF was found to be effective only for patients for secondary prevention.