Sustained and self-terminating atrial fibrillation induced immediately after pulmonary vein isolation exhibit differences in coronary sinus electrical activity from onset.

INTRODUCTION: Little data exists on the electrophysiological differences between sustained atrial fibrillation (sAF; >5 minutes) vs self-terminating nonsustained AF (nsAF; <5 minutes). We sought to investigate the electrophysiological characteristics of coronary sinus (CS) activity during postpulmonary vein isolation (PVI) sAF vs nsAF. METHODS AND RESULTS: We studied 142 patients post-PVI for paroxysmal AF (PAF). In a 50-patient subset, CS electrograms in the first 30 seconds of induced AF were analyzed manually. A custom-made algorithm for automated electrogram annotation was derived for validation on the whole patient set. In patients with sAF post-PVI, CS fractionated potentials were ablated. Manual analysis showed that patients with sAF exhibited higher activation pattern variability (2.1 vs 0.5 changes/sec; P < .001); fewer proximal-to-distal wavefronts (25 vs 61%; P < .001); fewer unidirectional wavefronts (60 vs 86%; P < .001); more pivot locations (4.3 vs 2.1; P < .001); shorter cycle lengths (190 vs 220 ms; P < .001); and shorter cumulative isoelectric segments (35 vs 44%; P = .045) compared to nsAF. These observations were confirmed on the whole study population by automated electrogram annotation and sample entropy computation (SampEn: 0.29 ± 0.15 in sAF vs 0.15 ± 0.05 in nsAF; P < .0001). The derived model predicted sAF with 78% sensitivity, 88% specificity; agreement with manual model: 88% (Cohen's kappa= 0.76). CS defragmentation resulted in AF termination or noninducibility in 49% of sAF. CONCLUSION: In PAF patients post-PVI, induced sAF shows greater activation sequence variability, shorter cycle length, and higher SampEn in the CS compared to nsAF. Automated electrogram annotation confirmed these results and accurately distinguished self-terminating nsAF episodes from sAF based on 30-second recordings at AF onset.

Idiopathic basal crux ventricular arrhythmias with left bundle branch block and superior axis: A comparison with inferior-septal valvular arrhythmias.

INTRODUCTION: Left bundle branch block (LBBB) with superior axis is common in patients with idiopathic-ventricular arrhythmia (VA) originating from the tricuspid annulus (TA) and rarely from the cardiac basal crux and mitral annulus (MA). We described the electrocardiography and electrophysiological findings of idiopathic-VA presenting with LBBB and superior axis. METHODS AND RESULTS: We described 42 idiopathic-VA patients who had an LBBB and superior axis; 15 basal crux-VA, 17 TA-VA, and 10 MA-VA. No patient had a structural heart disease. Among patients with idiopathic-VA referred for ablation, we investigated the electrocardiogram and clinical characteristics of basal crux-VA as compared with other LBBB and superior axis-VA. The left ventricular ejection fraction with MA-VA was significantly lower in comparison with basal crux-VA (P = .01). All patients had a positive R wave in lead I and aVL. The maximum deflection index with basal crux-VA was significantly higher in comparison with TA-VA or MA-VA (P = .01). Patients with basal crux-VA presented with QS wave in lead II more frequently as compared with TA-VA or MA-VA (P = .001). All MA-VA patients had Rs wave in V6, and basal crux-VA, and TA-VA patients had a monophasic R wave or Rs wave in V6. Basal crux-VA patients underwent ablation in the middle cardiac vein (MCV) or coronary sinus (success rate: 94%, recurrence rate: 6%). CONCLUSIONS: We could distinguish basal crux-VA, TA-VA, and MA-VA, using a combination of clinical and electrocardiographic findings. These findings might be useful for counseling patients about an ablation strategy. Ablation via the MCV is effective for eliminating basal crux-VA.

Electrically vs. imaging-guided left ventricular lead placement in cardiac resynchronization therapy: a randomized controlled trial.

AIMS: To test in a double-blinded, randomized trial whether the combination of electrically guided left ventricular (LV) lead placement and post-implant interventricular pacing delay (VVd) optimization results in superior increase in LV ejection fraction (LVEF) in cardiac resynchronization therapy (CRT) recipients. METHODS AND RESULTS: Stratified according to presence of ischaemic heart disease, 122 patients were randomized 1:1 to LV lead placement targeted towards the latest electrically activated segment identified by systematic mapping of the coronary sinus tributaries during CRT implantation combined with post-implant VVd optimization (intervention group) or imaging-guided LV lead implantation by cardiac computed tomography venography, 82Rubidium myocardial perfusion imaging and speckle tracking echocardiography targeting the LV lead towards the latest mechanically activated non-scarred myocardial segment (control group). Follow-up was 6 months. Primary endpoint was absolute increase in LVEF. Additional outcome measures were changes in New York Heart Association class, 6-minute walk test, and quality of life, LV reverse remodelling, and device related complications. Analysis was intention-to-treat. A larger increase in LVEF was observed in the intervention group (11 ± 10 vs. 7 ± 11%; 95% confidence interval 0.4-7.9%, P = 0.03); when adjusting for pre-specified baseline covariates this difference did not maintain statistical significance (P = 0.09). Clinical response, LV reverse remodelling, and complication rates did not differ between treatment groups. CONCLUSION: Electrically guided CRT implantation appeared non-inferior to an imaging-guided strategy considering the outcomes of change in LVEF, LV reverse remodelling and clinical response. Larger long-term studies are warranted to investigate the effect of an electrically guided CRT strategy.

Unique electrocardiographic pattern "w" wave in lead I of idiopathic ventricular arrhythmias arising from the distal great cardiac vein.

BACKGROUND: The ECG characteristics of the distal coronary venous system ventricular arrhythmias (VAs) share common features with VAs arising from the aortic cusps or the endocardial left ventricular outflow tract (LVOT) beneath the cusps. The purpose of this study was to identify specific electrocardiographic and electrophysiological characteristics of VAs originating from the distal great cardiac vein (GCV). METHODS: Based on the successful ablation site, patients with idiopathic VAs from the distal GCV, left coronary cusp (LCC) or the subvalvular left ventricular outflow tract (LVOT) area were included in the present study. RESULTS: The final population consisted of 39 patients (35 males, mean age 51 ± 23 years). All VAs displayed a right bundle branch block (RBBB) morphology with inferior axis. Among these patients, 15 were successfully ablated at the GCV, 15 at the LCC and 9 at the subvalvular region. A "w" pattern in lead I was present in 12 out of 15 (80%) VAs originating from the distal GCV compared to none of VAs arising from the other two sites (p < 0.01). VAs with a GCV origin exhibited more commonly increased intrinsicoid deflection time, higher maximum deflection index and wider QRS duration compared to LCC and subvalvular sites (p < 0.05). Acceptable pace mapping at the successful ablation site was achieved in 10 patients. After an average of 36 ± 24 months follow up, 14 (93.3%) patients were free from VAs recurrence. CONCLUSION: A "w" pattern in lead I may distinguish distal GCV VAs from VAs arising from the LCC or the subvalvular region.

Pseudoblock of the Posterior Mitral Line With Epicardial Bridging Connections Is a Frequent Cause of Complex Perimitral Tachycardias.

BACKGROUND: The mitral isthmus is the critical element of perimitral reentrant tachycardias. Prolongation in transisthmus conduction time and differential pacing techniques are commonly used to determine block. However, these may not distinguish block from slow conduction or conduction via epicardial bridging connections. The aim of this study was to examine these standard criteria for mitral line block with endocardial and epicardial activation mapping. METHODS: In 56 patients, posterior mitral line was performed using radiofrequency ablation. Conduction block was defined as transisthmus time (≥100 ms) and reversal of coronary sinus activation during pacing from the left atrial appendage. These results were compared with high-resolution activation mapping (Rhythmia) of the endocardium and epicardium via the coronary sinus. RESULTS: Mitral block determined by pacing was achieved in 51 out of 56 (91%) patients. In 11 out of 51 (21.6%), activation mapping demonstrated residual endocardial (3/11; 27.2%) or epicardial (8/11; 72.7%) connections. Epicardial bridging connections were distant from the line (2.4±1.6 cm), inserting laterally at the proximal-middle coronary sinus and septally at the left atrial ridge. Patients with residual conduction were prone to complex circuits involving the epicardium (7/11; 63.6%). Mitral line block was achieved in 75% by targeting these insertion site(s). The transisthmus conduction time had limited predictive value for distinguishing block from pseudoblock. CONCLUSIONS: Standard criteria for posterior mitral line block may not distinguish block from pseudoblock. In particular, epicardial bridging connections can result in prolonged transisthmus conduction time and reversal in coronary sinus activation to falsely suggest block. These connections are a frequent cause for complex circuits, and their insertion site(s) can be targeted for ablation.

Is adenosine useful for the identification of atrial fibrillation triggers?

INTRODUCTION: Both isoproterenol (Iso) and adenosine (Ado) are used to induce atrial fibrillation (AF) in the electrophysiology lab. However, the utility of Ado has not been systematically established. OBJECTIVE: The purpose of this study was to compare Ado to Iso for the induction of paroxysmal AF. METHODS: Forty patients (16 women; mean age, 60 ± 12 years) with paroxysmal AF, presenting for ablation were prospectively included of whom 36 (90%) received Ado (18-36 mg) and/or Iso (3-20 µg/min incremental dose) in a randomized order (26 [72%] received both drugs). RESULTS: AF was induced with Iso in 15 of 32 (47%) and with Ado in 12 of 30 (40%) patients (P = 0.9). Iso-triggered AF started from the left pulmonary veins (PVs) in 11 of 15 (73%), from the right PVs in 3 of 15 (20%), and from the coronary sinus (CS) in 1 of 15 (7%) cases. Ado-induced AF episodes originated from the left PVs in 6 of 12 (50%), from the right atrium (RA) in 4 of 12 (33%), and from the CS in 2 of 12 (17%) cases. Altogether, Iso-induced AF was more likely initiated from the PVs (93%) compared with Ado (50%) ( P = 0.02). Ado-induced non-PV triggers were not predictive of arrhythmia recurrence after PV isolation. CONCLUSION: Ado much more frequently induces non-PV triggers, especially from the RA. The clinical significance of these foci, however, is questionable.

Effect of radiofrequency on epicardial myocardium after ablation of ventricular arrhythmias from within coronary sinus.

BACKGROUND: Radiofrequency (RF) ablation of idiopathic ventricular arrhythmias (IVA) from the coronary venous system (CVS) has been increasingly performed, but real effect of ablation lesions from CVS on epicardial myocardium has not been studied. OBJECTIVE: To compare effects of RF delivered inside the distal CVS during ablation of IVAs originating from left ventricular summit (LVS) with IVAs ablated from right ventricular outflow tract (RVOT) using cardiac magnetic resonance imaging (CMRI). METHODS: Twenty consecutive patients with IVAs who underwent acutely successful RF ablation at initial appropriate sites, i.e., distal CVS (Group 1, n = 10) or RVOT (Group 2; n = 10) were enrolled. Detailed contrast-enhanced CMRI of each patient was performed 3 months later. Presence and location of scars, distance of CVS to epicardial ventricular myocardium were measured and analyzed. RESULTS: Group 1 consisted of 10 and Group 2 consisted of 10 patients. Three months after the ablation, only three patients in Group 1 had detectable late gadolinium enhancement (LGE) on CMRI while nine out of 10 patients in Group 2 had evident LGE on CMRI (P: 0.02). The mean distance of distal CVS to epicardial anterobasal myocardium was measured to be 8.8 ± 1.6 mm in Group 1. In three cases that had detectable scar on superior anterobasal LV epicardium, the mean distance was 7.4 ± 1.1 mm. CONCLUSIONS: RF delivery inside the CVS is less likely to produce detectable LGE on CMRI compared to RVOT. This may partially explain less than ideal long-term results after ablation of LVS IVAs from within the great cardiac vein/anterior interventricular vein.

Idiopathic ventricular arrhythmias originating from the right coronary sinus: Prevalence, electrocardiographic and electrophysiological characteristics, and catheter ablation.

BACKGROUND: Ventricular arrhythmias (VAs) of the right coronary cusp (RCC) are not fully characterized. OBJECTIVES: To investigate the electrocardiographic and electrophysiological characteristics, mapping and ablation of RCC-VAs. METHODS: Among 256 consecutive patients undergoing electrophysiological evaluation and ablation of VAs of ventricular outflow tract origin, data were compared among 27 RCC-VAs, 50 VAs of the septal aspect of right ventricular outflow tract (RVOT), including from pulmonary artery, and 9 VAs of left coronary cusp (LCC). RESULTS: The only electrocardiographic characteristic that differentiated VAs originating from the RCC and RVOT was the amplitude of the R wave in lead I. During VAs of the RCC, the earliest activation site (EAS) in the right ventricle was localized in the middle-posterior septal region of the RVOT. The distance between the His bundle and the EAS in the RVOT in the RCC group was shorter than that in the RVOT and LCC group; the distance ≤ 29.4 mm, which rules out an RVOT and LCC origin, had 92.6% sensitivity and 100% specificity for RCC-origin speculation. Double or complex potentials were recorded in RVOT middle-posterior septal area surrounding the EAS in 20 of 27 RCC-VA patients (70%). Most of the successful ablation sites (24/27) were located in the anterior and upper margin of the RCC, close to the middle-posterior septal region of the RVOT. The prepotential (P1) amplitude and the P1-to-QRS complex interval may be indicators of successful RCC-VA ablation sites. CONCLUSIONS: RCC-VAs are not uncommon and have unique electrocardiographic and electrophysiological characteristics that distinguish an RCC origin of VA from RVOT and LCC origins. Most RCC-VAs were ablated successfully in the anterior and upper aspects of the RCC.

Frequency Gradient Within Coronary Sinus Predicts the Long-Term Outcome of Persistent Atrial Fibrillation Catheter Ablation.

BACKGROUND: The coronary sinus (CS), as a junction of the atria, contributes to atrial fibrillation (AF) by developing unstable reentry, and isolating the atria by ablation at the CS could terminate AF. The present study evaluated whether AF activities at the CS in a subset of patients contributed to AF maintenance and predicted clinical outcome of ablation. METHODS AND RESULTS: We studied 122 consecutive patients who had a first-time radiofrequency ablation for persistent AF. Bipolar electrograms were obtained from multiple regions of the left atrium by a Lasso mapping catheter before ablation. Pulmonary vein isolation terminated AF in 12 patients (9.8%). Sequential stepwise ablation was conducted in pulmonary vein isolation nontermination patients and succeeded in 22 patients (18%). In the stepwise termination group, AF frequency in the proximal CS (CSp) was significantly higher (10.2±2.1 Hz versus 8.3±1.8 Hz, P<0.001), and the ratio of distal CS (CSd) to proximal CS (CSd/CSp ratio, 56.6%±10.11% versus 70.7%±9.8%, P<0.001) was significantly lower than that in the nontermination group. The stepwise logistic regression analysis indicated that the CSd/CSp ratio was an independent predictor with an odds ratio of 1.131 (95%CI 1.053-1.214; P=0.001). With a cutoff of 67%, the patients with lower CSd/CSp ratios had significantly better index and long-term outcomes than those with higher ratios during a follow-up of 46±18 months. CONCLUSIONS: Rapid repetitive activities in the musculature of the proximal CS may contribute to maintenance of AF after pulmonary vein isolation alone in persistent AF. A cutoff at 67%, of the CSd/CSp frequency ratio might be an indicator to stratify the subset of patients who might benefit from CS ablation.