Repeat ablation of atrial fibrillation using electrogram dispersion to identify additional areas of mechanistic significance.

Background: Electrogram dispersion identifies putative atrial fibrillation (AF) drivers in first time ablation procedures, with high acute termination rates and long-term outcomes akin to extensive ablation approaches. Its use in a population that had undergone repeat ablation is unknown, particularly where the pulmonary veins are already isolated. Objective: This purpose of this study was to assess electrogram dispersion mapping during repeat ablation procedures for persistent AF. Methods: One hundred sixty-seven patients from the United Kingdom and Denmark, all with persistent AF recurrence after prior ablation procedure(s), were mapped using a five splined catheter for electrogram dispersion before ablation. Areas were manually tagged on biatrial electroanatomic maps and ablated once pulmonary vein isolation was confirmed or reisolated if required. All patients had 12-month continuous monitoring, with most of the cohort having follow-up beyond 24 months. Results: Of the 167 patients [53 (32%) female; mean age 66 ± 8 years; mean left atrial (LA) diameter 4.8 cm; mean ejection fraction 53%], 108 had pulmonary veins already isolated. Dispersion sites occurred in both atria (3.2 LA, 1.4 right atrium). Acute termination to sinus rhythm occurred in 71 (42%) of the cohort patients, with a further 73 (44%) terminating to atrial tachycardia/flutter. At 12-month follow-up, 95% of patients were free of AF, with 74% overall freedom from all atrial arrhythmias. Heart failure and severely enlarged LA predicted recurrence, and termination to sinus improved freedom from all atrial arrhythmias. Conclusion: Dispersion mapping is a promising approach at repeat ablation procedures for persistent AF, with high acute termination rates and good clinical outcomes. Further prospective randomized trials are needed to evaluate this approach in a population that had undergone repeat ablation.

Social determinants of health and recurrence of atrial fibrillation after catheter ablation: a Danish nationwide cohort study.

AIMS: To examine the associations between three social determinants of health (SDOH) and recurrence of AF after ablation. METHODS AND RESULTS: We selected patients who underwent a first ablation after an incident hospital diagnosis of AF between 2005 and 2018 from the entire Danish population. Educational attainment, family income, and whether the patient was living alone were assessed at the time of ablation. We used cause-specific proportional hazard models to estimate hazard ratios (HR) with 95% confidence interval (CI) adjusted for age and sex. In secondary analyses, we adjusted for comorbidities, antiarrhythmic medication, and prior electrical cardioversion.We selected 9728 patients (mean age 61 years, 70% men), and 5881 patients had AF recurrence over an average of 1.37 years after ablation (recurrence rate 325.7 (95% CI 317.6-334.2) per 1000 person-years). Lower education (HR 1.09 [1.02-1.17] and 1.07 [1.01-1.14] for lower and medium vs. higher), lower income [HR 1.14 (1.06-1.22) and 1.09 (1.03-1.17) for lower and medium vs. higher], and living alone [HR 1.07 (1.00-1.13)] were associated with increased rates of recurrence of AF. We found no evidence of interaction between sex or prior HF with SDOH. The association between family income and AF recurrence was stronger among patients < 65 years compared with those aged ≥ 65 years. The associations between SDOH and AF recurrence did not persist in the multivariable model. CONCLUSION: AF was more likely to recur among patients with lower educational attainment, lower family income, or those living alone. Multidisciplinary efforts are needed to reduce socioeconomic inequity in the effect of ablation.

Reproducibility and repeatability of identifying the latest electrical activation during mapping of coronary sinus branches in CRT recipients.

INTRODUCTION: Studies have shown an association between the outcome in cardiac resynchronization therapy (CRT) and longer interventricular delay at the site of the left ventricular (LV) lead. Targeted LV lead placement at the latest electrically activated segment increases LV function further as compared with standard treatment. We aimed to determine reproducibility and repeatability of identifying the latest electrically activated segment during mapping of all available coronary sinus (CS) branches in patients receiving CRT. METHODS: We included 35 patients who underwent CRT implantation with protocolled mapping guided LV lead implantation aiming for the site of the latest electrical activation. Three different doctors experienced in electrophysiology and implantation of CRT devices independently measured time interval from the local bipolar right ventricular (RV) electrogram (EGM) to the local unipolar LV EGM at all mapped sites (RV-LV). The segment with the latest electrical activation was defined as the target segment (TS) and the CS tributary containing TS was defined as the target vein (TV). Weighted κ statistics with 95% confidence intervals were computed to assess intra- and interobserver agreement for TS and TV. RESULTS: We mapped 258 segments within 131 veins. Weighted κ values for repeatability were 0.85 (0.81-0.89) for TS and 0.92 (0.89-0.93) for TV, and weighted κ values of interobserver agreement ranged from 0.70 (0.61-0.73) to 0.80 (0.76-0.83) for TS and 0.73 (0.64-0.78) to 0.86 (0.83-0.89) for TV among all three observers. CONCLUSION: The reproducibility and repeatability of identifying the latest electrically activated segment during mapping of all available CS branches in patients receiving CRT range from good to very good.

Transmural Myocardial Scar Assessed by Cardiac Computed Tomography: Predictor of Echocardiographic Versus Clinical Response to Cardiac Resynchronization Therapy?

OBJECTIVES: Before cardiac resynchronization therapy (CRT) implantation, cardiac computed tomography (CT) can provide assessment of cardiac venous anatomy and visualize left ventricular (LV) myocardial scar. We hypothesized that localization and burden of transmural myocardial scar verified by cardiac CT are associated with echocardiographic and clinical response to CRT. METHODS: We prospectively included 140 CRT recipients undergoing preimplant cardiac CT. We assessed transmural scar, defined as hypoperfusion involving more than one-half of the myocardial wall in each LV segment using a 17-segment model. Echocardiographic nonresponse was defined as less than 5% absolute improvement in LV ejection fraction at 6 months' follow-up. Clinical nonresponse was defined as 1 or more of the following at 6 months' follow-up: death, heart failure hospitalization, or no improvement in New York Heart Association class and less than 10% increase in 6-minute walk-test distance. RESULTS: Higher burden of myocardial scar was associated with echocardiographic nonresponse (adjusted odds ratio, 3.02; 95% confidence interval, 1.03-8.91; P = 0.045). Scar concordant or adjacent to LV pacing site was associated with echocardiographic nonresponse (adjusted odds ratio, 8.2; 95% confidence interval, 1.51-44.27; P = 0.015). No association between scar and clinical nonresponse was demonstrated. CONCLUSIONS: Higher scar burden and scar in proximity to the LV pacing site assessed by cardiac CT are associated with echocardiographic nonresponse to CRT. Burden and location of scar were not associated with clinical nonresponse. Further large-scale studies are needed to assess the potential association between myocardial scar detected by cardiac CT and clinical CRT outcome.

His or para-His pacing preserves left ventricular function in atrioventricular block: a double-blind, randomized, crossover study.

AIMS: To compare left ventricular function after a long-term His or para-His pacing (HP) and right ventricular septal pacing (RVSP) in patients with atrioventricular block (AVB). METHODS AND RESULTS: We included consecutive patients with AVB, a narrow QRS < 120 ms, and a preserved left ventricular ejection fraction (LVEF) >0.40, in a prospective, randomized, double-blinded, crossover design. All patients were treated with 12 months HP and 12 months RVSP. A total of 38 patients [mean age, 67 ± 10 years; 30 (79%) men] were included. The primary endpoint was LVEF, which was significantly lower after a 12 months RVSP (0.50 ± 0.11) than after 12 months of HP (0.55 ± 0.10), P = 0.005. We measured the difference in time-to-peak systolic velocity between opposite basal segments in the apical views by using tissue Doppler imaging. In the four-chamber view, the difference was 58 (±7) ms after RVSP and 49 (±7) ms after HP, P = 0.27; in the two-chamber view, the difference was 45 (±5) ms after RVSP and 31 ±(4) ms after HP, P = 0.02, and in the apical long-axis view, the difference was 63 (±6) after RVSP and 44 (±7) after HP, P = 0.03. There was no difference in New York Heart Association class, 6-min hall walk test, quality-of-life assessments, or device-related complications. The mean threshold was significantly higher in HP leads than in RVSP leads. CONCLUSION: His or para-His pacing preserves LVEF and mechanical synchrony as compared with RVSP after 12 months pacing in patients with AVB, narrow QRS, and LVEF > 0.40.

Simple regional strain pattern analysis to predict response to cardiac resynchronization therapy: rationale, initial results, and advantages.

BACKGROUND: A classical strain pattern of early contraction in one wall and prestretching of the opposing wall followed by late contraction has previously been associated with left bundle branch block (LBBB) activation and short-term response to cardiac resynchronization therapy (CRT). Aims of this study were to establish the long-term predictive value of an LBBB-related strain pattern and to identify changes in contraction patterns during short-term and long-term CRT. METHODS AND RESULTS: Sixty-seven patients with standard CRT criteria were prospectively enrolled between early 2009 and late 2010. Echocardiography including regional strain analysis by 2-dimensional speckle tracking was performed 1 week before implantation, at day 1, and 6 months after. Response was defined as a decrease in left ventricular end-systolic volume ≥ 15%. The predictive ability of a classical pattern was compared with time-to-peak measurements from velocity and deformation analysis. Forty-three patients (65%) were classified as responders. The presence of a classical pattern showed 91% specificity and 95% sensitivity for response and performed significantly better than time-to-peak parameters in prediction of response to CRT (P < .001, all). In responders, CRT acutely increased septal longitudinal peak systolic strain (-8.7% ± 3.6% to -11.1% ± 3%, P < .001) but not in nonresponders. CONCLUSIONS: The classical pattern is highly predictive of response to CRT and superior to time-to-peak methods. Patients who obtain long-term reverse remodeling are characterized by short-term reversal of the classical strain pattern. These findings emphasize the value of recognizing potentially reversible strain patterns in selection of CRT candidates.

Degenerative processes in bioprosthetic mitral valves in juvenile pigs.

BACKGROUND: Glutaraldehyde-treated bioprosthetic heart valves are commonly used for replacement of diseased heart valves. However, calcification and wear limit their durability, and the development of new and improved bioprosthetic valve designs is needed and must be evaluated in a reliable animal model. We studied glutaraldehyde-treated valves 6 months after implantation to evaluate bioprosthetic valve complications in the mitral position in juvenile pigs. MATERIALS: The study material comprised eight, 5-month old, 60-kg pigs. All pigs received a size 27, glutaraldehyde-treated, stented, Carpentier-Edwards S.A.V. mitral valve prosthesis. After six months, echocardiography was performed, and the valves explanted for gross examination, high resolution X-ray, and histological evaluation. RESULTS: Five pigs survived the follow-up period. Preexplant echocardiography revealed a median peak and mean velocity of 1.61 m/s (range: 1.17-2.00) and 1.20 (SD = ±0.25), respectively, and a median peak and mean pressure difference of 10.42 mmHg (range: 5.83-16.55) and 6.51 mmHg (SD = ±2.57), respectively. Gross examination showed minor thrombotic depositions at two commissures in two valves and at all three commissures in three valves. High resolution X-ray imaging revealed different degrees of calcification in all explanted valves, primarily in the commissural and belly areas. In all valves, histological evaluation demonstrated various degrees of fibrous sheath formation, limited immunological infiltration, and no overgrowth of host endothelium. CONCLUSIONS: Bioprosthetic glutaraldehyde-treated mitral valves can be implanted into the mitral position in pigs and function after 6 months. Echocardiographic data, calcification, and histological examinations were comparable to results obtained in sheep models and human demonstrating the suitability of the porcine model.

Electrocardiographic patterns and long-term clinical outcome in cardiac resynchronization therapy.

AIMS: The present study aims to identify the predictive value of electrocardiographic (ECG) patterns on long-term clinical and echocardiographic outcome in patients treated with cardiac resynchronization therapy (CRT). METHODS AND RESULTS: Clinical information including a standard 12-lead ECG was collected from patient files in consecutive patients treated with CRT from 1997 to 2007. Symptomatic response was defined as improvement in New York Heart Association class (> or =1) and echocardiographic response as improvement in left ventricular ejection fraction of > or =5% absolute. We included 659 patients [median age 66 years, 526 (80%) male]. There was a higher all-cause and cardiac mortality in patients with left bundle branch block (LBBB), prolonged PR interval, right-axis deviation combined with LBBB in the pre-implant ECG, and no QRS reduction after CRT. Patients with right bundle branch block and patients with an intermediate QRS duration (150-200 ms) had a higher chance of symptomatic improvement, and patients with normal PR interval and normal axis in LBBB had a higher chance of echocardiographic improvement. CONCLUSION: Cardiac resynchronization therapy does not change the predictive value of ECG patterns in heart failure patients with bundle branch block, where LBBB, a prolonged PR, and an abnormal axis in LBBB are signs of a more severe degree of myocardial disease, and therefore a worse outcome. Lack of electrical resynchronization defined as an unchanged or prolonged QRS duration is associated with higher all-cause and cardiac mortality in patients treated with CRT.