Miki Yokokawa

Dabigatran vs warfarin for radiofrequency catheter ablation of atrial fibrillation

BACKGROUND It is not clear whether dabigatran is as safe and effective as uninterrupted anticoagulation with warfarin during radiofrequency catheter ablation (RFA) of atrial fibrillation (AF). OBJECTIVE To compare the safety and efficacy of dabigatran by using a novel administration protocol and uninterrupted anticoagulation with warfarin for periprocedural anticoagulation in patients undergoing RFA of AF. METHODS In this case-control analysis, 763 consecutive patients (mean age 61±10 years) underwent RFA of AF using dabigatran (N = 191) or uninterrupted warfarin (N = 572) for periprocedural anticoagulation. In all patients, anticoagulation was started≥4 weeks before RFA. Dabigatran was held after the morning dose on the day before the procedure and resumed 4 hours after vascular hemostasis was achieved. RESULTS A transesophageal echocardiogram performed in all patients receiving dabigatran did not demonstrate an intracardiac thrombus. There were no thromboembolic complications in either group. The prevalence of major (4 of 191, 2.1%) and minor (5 of 191, 2.6%) bleeding complications in the dabigatran group were similar to those in the warfarin group (12 of 572, 2.1%; P = 1.0 and 19 of 572, 3.3%; P = .8, respectively). Pericardial tamponade occurred in 2 of 191 (1%) patients in the dabigatran group and in 7 of 572 (1.2%) patients in the warfarin group (P = 1.0). All patients who had a pericardial tamponade, including 2 in the dabigatran group, had uneventful recovery after perdicardiocentesis. On multivariate analysis, international normalized ratio (odds ratio [OR] 4.0; 95% confidence interval [CI] 1.1-15.0; P = .04), clopidogrel use (OR 4.2; 95% CI 1.5-12.3; P = .01), and CHA2DS2-VASc score (OR 1.4; 95% CI 1.1-1.8; P = .01) were the independent risk factors of bleeding complications only in the warfarin group. CONCLUSIONS When held for approximately 24 hours before the procedure and resumed 4 hours after vascular hemostasis, dabigatran appears to be as safe and effective as uninterrupted warfarin for periprocedural anticoagulation in patients undergoing RFA of AF.

Recovery from left ventricular dysfunction after ablation of frequent premature ventricular complexes.

BACKGROUND Patients with frequent premature ventricular complexes (PVCs) and PVC-induced cardiomyopathy usually have recovery of left ventricular (LV) dysfunction postablation. The time course of recovery of LV function has not been described. OBJECTIVE To describe the time course and predictors of recovery from LV dysfunction after effective ablation of PVCs in patients with PVC-induced cardiomyopathy. METHODS In a consecutive series of 264 patients with frequent idiopathic PVCs referred for PVC ablation, LV dysfunction was present in 87 patients (mean ejection fraction 40%±10%). The PVC burden was reduced to<20% of the initial PVC burden in 75 patients. In these patients, echocardiography was repeated 3-4 months postablation. If LV function did not normalize after 3-4 months, a repeat echocardiogram was performed every 3 months until there was normalization or stabilization of LV function. RESULTS The ejection fraction normalized at a mean of 5±6 months postablation. The majority of patients (51 of 75, 68%) with PVC-induced LV dysfunction had a recovery of LV function within 4 months. In 24 (32%) patients, recovery of LV function took more than 4 months (mean 12±9 months; range 5-45 months). An epicardial origin of PVCs was more often present (13 of 24, 54%) in patients with delayed recovery of LV function than in patients with early recovery of LV function (2 of 51, 4%; P<.0001). The PVC-QRS width was significantly longer in patients with delayed recovery than in patients with recovery within 4 months (170±21 ms vs 159±16 ms; P = .02). In multivariate analysis, only an epicardial PVC origin was predictive of delayed recovery of LV function in patients with PVC-induced cardiomyopathy. CONCLUSIONS PVC-induced cardiomyopathy resolves within 4 months of successful ablation in most patients. In about one-third of the patients, recovery is delayed and can take up to 45 months. An epicardial origin predicts delayed recovery of LV function.

Impact of QRS duration of frequent premature ventricular complexes on the development of cardiomyopathy

BACKGROUND Patients with frequent premature ventricular complexes (PVCs) are at risk of developing reversible PVC-induced cardiomyopathy (rPVC-CMP). Not all determinants of rPVC-CMP are known. OBJECTIVE To assess the impact of the QRS duration of PVCs on the development of rPVC-CMP. METHODS In a consecutive series of 294 patients with frequent idiopathic PVCs referred for PVC ablation, the width of the PVC-QRS complex was assessed. The QRS width was correlated with the presence of rPVC-CMP. RESULTS The PVC-QRS width was significantly greater in patients with rPVC-CMP than in patients without rPVC-CMP (164 ± 20 ms vs 149 ± 17 ms; P < .0001). The site of origin of the PVC had an impact on the PVC-QRS width, with epicardial PVCs having the broadest QRS complexes. Patients with PVCs originating from the right ventricular outflow tract or the fascicles had the narrowest QRS complexes. After adjusting for PVC burden, symptom duration, and PVC site of origin, PVC-QRS width and an epicardial PVC origin were independently associated with rPVC-CMP. Based on receiver operator characteristics analysis, a QRS duration of >150 ms best differentiated patients with and without rPVC-CMP (area under the curve 0.66; sensitivity 80%; specificity 52%). The PVC burden for developing rPVC-CMP is significantly lower in patients with a PVC-QRS width of ≥150 ms than in patients with a narrower PVC-QRS complex (22% ± 13% vs 28% ± 12%; P < .0001). CONCLUSION Broader PVCs and an epicardial PVC origin are associated with the development of rPVC-CMP independent of the PVC burden.

The role of interpolation in PVC-induced cardiomyopathy

BACKGROUND Frequent premature ventricular complexes (PVCs) can cause cardiomyopathy. The mechanism is not known and may be multifactorial. OBJECTIVE This study assessed the role of PVC interpolation in PVC-induced cardiomyopathy. METHODS In 51 consecutive patients (14 women, age 49 ± 15 years, ejection fraction (EF) 0.49 ± 0.14) with frequent PVCs, 24-hour Holter recordings were performed. The amount of interpolation was determined and correlated with the presence of PVC-induced cardiomyopathy. In addition, parameters measured during an electrophysiology study were correlated with the Holter findings. RESULTS Fourteen of the 21 patients (67%) with cardiomyopathy had interpolated PVCs, compared with only 6 of 30 patients (20%) without PVC-induced cardiomyopathy (P <.001). Patients with interpolated PVCs had a higher PVC burden than patients without interpolation (28% ± 12% vs. 15% ± 15%; P = .002). The burden of interpolated PVCs correlated with the presence of PVC cardiomyopathy (21% ± 30% vs. 4% ± 13%; P = .008). Both PVC burden and interpolation independently predicted PVC-induced cardiomyopathy (odds ratio 1.07, 95% confidence interval 1.01 to 1.13, P = .02; and odds ratio 4.43, 95% confidence interval 1.06 to 18.48, P = .04, respectively). The presence of ventriculoatrial block at a ventricular pacing cycle length of 600 ms correlated with the presence of interpolation (P = .004). Patients with interpolation had a longer mean ventriculoatrial block cycle length than patients without interpolated PVCs (520 ± 110 ms vs. 394 ± 92 ms; P = .01). CONCLUSION The presence of interpolated PVCs was predictive of the presence of PVC cardiomyopathy. Interpolation may play an important role in the generation of PVC-induced cardiomyopathy.

The Value of Defibrillator Electrograms for Recognition of Clinical Ventricular Tachycardias and for Pace Mapping of Post-Infarction Ventricular Tachycardia

OBJECTIVES The purpose of this study was to assess the value of implantable cardioverter-defibrillator (ICD) electrograms (EGMs) in identifying clinically documented ventricular tachycardias (VTs). BACKGROUND Twelve-lead electrocardiograms (ECG) of spontaneous VT often are not available in patients referred for catheter ablation of post-infarction VT. Many of these patients have ICDs, and the ability of ICD EGMs to identify a specific configuration of VT has not been described. METHODS In 21 consecutive patients referred for catheter ablation of post-infarction VT, 124 VTs (mean cycle length: 393 ± 103 ms) were induced, and ICD EGMs were recorded during VT. Clinical VT had been documented with 12-lead ECGs in 15 of 21 patients. The 12-lead ECGs of the clinical VTs were compared with 64 different inducible VTs (mean cycle length: 390 ± 91 ms) to assess how well the ICD EGMs differentiated the clinical VTs from the other induced VTs. The exit site of 62 VTs (mean cycle length: 408 ± 112 ms) was identified by pace mapping (10 to 12 of 12 matching leads). The spatial resolution of pace mapping to identify a VT exit site was determined for both the 12-lead ECGs and the ICD EGMs using a customized MATLAB program (version 7.5, The MathWorks, Inc., Natick, Massachusetts). RESULTS Analysis of stored EGMs by comparison of receiver-operating characteristic curve cutoff values accurately distinguished the clinical VTs from 98% of the other inducible VTs. The mean spatial resolution of a 12-lead ECG pace map for the VT exit site was 2.9 ± 4.0 cm(2) (range 0 to 17.5 cm(2)) compared with 8.9 ± 9.0 cm(2) (range 0 to 35 cm(2)) for ICD EGM pace maps. The spatial resolution of pace mapping varied greatly between patients and between VTs. The spatial resolution of ICD EGMs was < 1.0 cm(2) for ≥ 1 of the target VTs in 12 of 21 patients and 19 of 62 VTs. By visual inspection of the ICD EGMs, 96% of the clinical VTs were accurately differentiated from previously undocumented VTs. CONCLUSIONS Stored ICD EGMs usually are an accurate surrogate for 12-lead ECGs for differentiating clinical VTs from other VTs. Pace mapping based on ICD EGMs has variable resolution but may be useful for identifying a VT exit site.

Impact of mitral isthmus anatomy on the likelihood of achieving linear block in patients undergoing catheter ablation of persistent atrial fibrillation

BACKGROUND Although prior studies have described the anatomy of the mitral isthmus in patients undergoing left atrial (LA) ablation of atrial fibrillation (AF), none has examined the impact of isthmus anatomy on the likelihood of achieving conduction block. OBJECTIVE The purpose of this study was to identify morphologic characteristics of the mitral isthmus that may influence the acute efficacy of linear ablation at the mitral isthmus. METHODS Fifty-five patients (age 61 ± 10 years, 41 [75%] men, LA 46 ± 6 mm, ejection fraction 0.55 ± 0.11, AF duration 4 ± 3 years) underwent linear ablation at the mitral isthmus during an ablation procedure for persistent AF. Computed tomographic scan was performed before the procedure. The morphology of the mitral isthmus and its anatomic relationship to the adjacent vasculature were analyzed. RESULTS Complete block along the mitral isthmus was achieved in 35 (64%) of 55 patients, 23 (66%) of whom required radiofrequency ablation in the coronary sinus (CS). Patients with incomplete block were more likely to have a pouch at the isthmus (40% vs 9%; P = .01), a greater isthmus depth (8.1 ± 4.2 mm vs 5.7 ± 3.4 mm; P = .04), and a higher prevalence of an interposed circumflex artery between the CS and the mitral isthmus (60% vs 20%; P = .003) compared to patients with isthmus block. An interposed circumflex artery was the only independent predictor of incomplete conduction block at the mitral isthmus (odds ratio 4.9, 95% confidence interval 1.3-18.2; P = .02). CONCLUSION Preprocedural computed tomographic imaging identifies patients in whom linear ablation at the mitral isthmus is unlikely to be successful. Interposition of the circumflex artery between the mitral isthmus and the CS is associated with a lower probability of achieving complete mitral isthmus block.

Predictive Value of Programmed Ventricular Stimulation After Catheter Ablation of Post-Infarction Ventricular Tachycardia

BACKGROUND A recent meta-analysis demonstrated a survival benefit in post-infarction patients whose ventricular tachycardia (VT) was rendered noninducible by catheter ablation. Furthermore, patients with noninducible VT had a lower VT recurrence rate than did patients whose VT remained inducible after ablation. OBJECTIVES The purpose of this multicenter cohort study was to assess whether noninducibility after VT ablation is independently associated with improved survival. METHODS Data from 1,064 patients who underwent VT ablation for post-infarction VT at seven international centers were analyzed. The ablation procedure was considered successful if no VT was inducible at the end of the procedure and unsuccessful if VT remained inducible or if programmed stimulation was not performed at the end of the ablation. RESULTS Median follow-up time was 633 days. Noninducibility was independently associated with lower mortality (adjusted hazard ratio: 0.65; 95% confidence interval: 0.53 to 0.79; p<0.001). Atrial fibrillation, diabetes, and age were other independent predictors of higher mortality. Ablation of only the clinical VT in patients who also had inducible, nonclinical VTs was not associated with improved survival. CONCLUSIONS Noninducibility after VT ablation in patients with post-infarction VT is independently associated with lower mortality during long-term follow-up.

Noninducibility in postinfarction ventricular tachycardia as an end point for ventricular tachycardia ablation and its effects on outcomes a meta-analysis

Background—Although ventricular tachycardia (VT) ablation is a widely used therapy for patients with VT, the ideal end points for this procedure are not well defined. We performed a meta-analysis of the published literature to assess the predictive value of noninducibility of postinfarction VT for long-term outcomes after VT ablation. Methods and Results—We performed a systematic review of MEDLINE (1950–2013), EMBASE (1988–2013), the Cochrane Controlled Trials Register (Fourth Quarter, 2012), and reports presented at scientific meetings (1994–2013). Randomized controlled trials, case–control, and cohort studies of VT ablation were included. Outcomes reported in eligible studies were freedom from VT/ventricular fibrillation and all-cause mortality. Of the 3895 studies evaluated, we identified 8 cohort studies enrolling 928 patients for the meta-analysis. Noninducibility after VT ablation was associated with a significant increase in arrhythmia-free survival compared with partial success (odds ratio, 0.49; 95% confidence interval, 0.29–0.84; P=0.009) or failed ablation procedure (odds ratio, 0.10; 95% confidence interval, 0.06–0.18; P<0.001). There was also a significant reduction in all-cause mortality if patients were noninducible after VT ablation compared with patients with partial success (odds ratio, 0.59; 95% confidence interval, 0.36–0.98; P=0.04) or failed ablation (odds ratio, 0.32; 95% confidence interval, 0.10–0.99; P=0.049). Conclusions—Noninducibility of VT after VT ablation is associated with improved arrhythmia-free survival and all-cause mortality.

Reasons for Recurrent Ventricular Tachycardia After Catheter Ablation of Post-Infarction Ventricular Tachycardia

OBJECTIVES The purpose of this study was to assess the determinants of ventricular tachycardia (VT) recurrence in patients who underwent VT ablation for post-infarction VT. BACKGROUND The factors that predict recurrence of VT after catheter ablation in patients with prior infarctions are not well described. METHODS Catheter ablation was performed in 98 consecutive patients (88 males [90%]; mean age 67 ± 10 years; ejection fraction 27 ± 13%) with post-infarction VT. Electrograms from the implantable cardioverter-defibrillator were analyzed, and VTs were classified as clinical, nonclinical, or new clinical. RESULTS A total of 725 VTs were induced during the ablation procedure. All VTs were targeted. In 76 patients, 105 clinical VTs were inducible. Critical sites were identified with entrainment mapping and pace-mapping (≥10 of 12 matching leads) for 75 of 105 clinical VTs (71%) and for 278 of 620 nonclinical VTs (45%). Post-ablation, the clinical VT was not inducible in any patient, and all VTs were rendered noninducible in 63% of the patients. Over a mean follow-up period of 35 ± 23 months, 65 of 98 patients (66%) had no recurrent VTs and 33 (34%) had VT recurrence. A new VT occurred in 26 of 33 patients (79%), and a prior clinical VT recurred in 7 patients (21%). Patients with recurrent VT had a larger scar area as assessed by electroanatomic mapping compared with patients without recurrent VTs (93 ± 40 cm(2) vs. 69 ± 30 cm(2); p = 0.002). In patients with repeat procedures, the majority of inducible VTs for which a critical area could be identified were at a distance of 6 ± 3 mm to the prior ablation lesions. CONCLUSIONS Patients with recurrent VTs have a larger scar as assessed by electroanatomic mapping. Most recurrent VTs were new, and the majority of these VTs were mapped to the vicinity of prior ablation lesions in patients with repeat procedures.

Prevalence and Characterization of Pulmonary Vein Variants in Patients With Atrial Fibrillation Determined Using 3-Dimensional Computed Tomography

Although several branching patterns of pulmonary veins (PVs) were reported, their prevalence and characterization were not sufficiently clarified. Multislice computed tomography was performed in 428 patients who underwent catheter ablation for drug-refractory atrial fibrillation. Size and branching pattern of PVs were analyzed. A typical pattern of 4 PVs with 4 separate ostia was found in 326 patients (76%). However, a common PV trunk, defined as a PV with coalescence of superior and inferior PVs > or =1.5 cm proximal to the junction with the left atrium, was found on the left side in 34 patients (8%) and right side in 3 patients (0.76%). A discrete middle PV was found on the right side in 54 patients (13%) and left side in 9 patients (2%). A right top PV, defined as an anomalous insertion of a branch of the right superior PV into the left atrial body, was also found in 16 patients (4%). In conclusion, 24% of our patients with atrial fibrillation had PV anomalies and 3% had coexistence of 2 PV variants, indicating that PV variants are not rare.