Kevin P. Jackson

Pulmonary Vein Isolation for the Maintenance of Sinus Rhythm in Patients with Atrial Fibrillation: a Meta-Analysis of Randomized Controlled Trials

Background—Catheter ablation is an established yet evolving nonpharmacologic intervention for the maintenance of sinus rhythm in patients with atrial fibrillation (AF). The efficacy and safety of pulmonary vein isolation (PVI) compared with medical therapy remain in question. Methods and Results—We conducted a meta-analysis of all randomized, controlled trials comparing PVI and medical therapy for the maintenance of sinus rhythm. The primary end point in this analysis was freedom from recurrent AF at 12 months. The relative efficacy of PVI was estimated using random-effects modeling according to intention to treat. We identified 6 trials that randomized a total of 693 patients with AF to PVI or control. PVI was associated with markedly increased odds of freedom from AF at 12 months of follow-up (n=266/344 [77%] versus n=102/346 [29%]; odds ratio, 9.74; 95% CI, 3.98 to 23.87). When we excluded the trial that only enrolled patients with persistent AF (Q-statistic, 2.485; P=0.647 after exclusion), PVI was associated with even greater odds of AF-free survival (15.78; 95% CI, 10.07 to 24.73). PVI was associated with a decreased hospitalization for cardiovascular causes (14 versus 93 per 100 person-years; rate ratio, 0.15; 95% CI, 0.10 to 0.23). Among those randomly assigned to PVI, 17% required a repeat PVI ablation before 12 months. The rate of major complications was 2.6% (n=9/344) in the catheter ablation group. Conclusions—Compared with a nonablation treatment strategy, PVI results in dramatically increased freedom from AF at 1 year. Although the procedure can be associated with major complications, the risk of these complications is comparable to other interventional procedures.

Mechanical dyssynchrony evaluated by tissue Doppler cross-correlation analysis is associated with long-term survival in patients after cardiac resynchronization therapy

AIMS Pre-implant assessment of longitudinal mechanical dyssynchrony using cross-correlation analysis (XCA) was tested for association with long-term survival and compared with other tissue Doppler imaging (TDI)-derived indices. METHODS AND RESULTS In 131 patients referred for cardiac resynchronization therapy (CRT) from two international centres, mechanical dyssynchrony was assessed from TDI velocity curves using time-to-peak opposing wall delay (OWD) ≥80 ms, Yu index ≥32 ms, and the maximal activation delay (AD-max) >35 ms. AD-max was calculated by XCA of the TDI-derived myocardial acceleration curves. Outcome was a composite of all-cause mortality, cardiac transplantation, or implantation of a ventricular assist device (left ventricular assist device) and modelled using the Cox proportional hazards regression. Follow-up was truncated at 1460 days. Dyssynchrony by AD-max was independently associated with improved survival when adjusted for QRS > 150 ms and aetiology {hazard ratio (HR) 0.35 [95% confidence interval (CI) 0.16-0.77], P = 0.01}. Maximal activation delay performed significantly better than Yu index, OWD, and the presence of left bundle branch block (P < 0.05, all, for difference between parameters). In subgroup analysis, patients without dyssynchrony and QRS between 120 and 150 ms showed a particularly poor survival [HR 4.3 (95% CI 1.46-12.59), P < 0.01, compared with the group with dyssynchrony and QRS between 120 and 150 ms]. CONCLUSION Mechanical dyssynchrony assessed by AD-max was associated with long-term survival after CRT and was significantly better associated compared with other TDI-derived indices. Patients without dyssynchrony and QRS between 120 and 150 ms had a particularly poor prognosis. These results indicate a valuable role for XCA in selection of CRT candidates.

Long-term outcomes in leadless Micra transcatheter pacemakers with elevated thresholds at implantation: Results from the Micra Transcatheter Pacing System Global Clinical Trial

BACKGROUND Device repositioning during Micra leadless pacemaker implantation may be required to achieve optimal pacing thresholds. OBJECTIVE The purpose of this study was to describe the natural history of acute elevated Micra vs traditional transvenous lead thresholds. METHODS Micra study VVI patients with threshold data (at 0.24 ms) at implant (n = 711) were compared with Capture study patients with de novo transvenous leads at 0.4 ms (n = 538). In both cohorts, high thresholds were defined as >1.0 V and very high as >1.5 V. Change in pacing threshold (0-6 months) with high (1.0 to ≤1.5 V) or very high (>1.5 V) thresholds were compared using the Wilcoxon signed-rank test. RESULTS Of the 711 Micra patients, 83 (11.7%) had an implant threshold of >1.0 V at 0.24 ms. Of the 538 Capture patients, 50 (9.3%) had an implant threshold of >1.0 V at 0.40 ms. There were no significant differences in patient characteristics between those with and without an implant threshold of >1.0 V, with the exception of left ventricular ejection fraction in the Capture cohort (high vs low thresholds, 53% vs 58%; P = .011). Patients with an implant threshold of >1.0 V decreased significantly (P < .001) in both cohorts. Micra patients with high and very high thresholds decreased significantly (P < .01) by 1 month, with 87% and 85% having 6-month thresholds lower than the implant value. However, when the capture threshold at implant was >2 V, only 18.2% had a threshold of ≤1 V at 6 months and 45.5% had a capture threshold of >2 V. CONCLUSIONS Pacing thresholds in most Micra patients with elevated thresholds decrease after implant. Micra device repositioning may not be necessary if the pacing threshold is ≤2 V.

The electrocardiogram in left ventricular hypertrophy: past and future

The electrocardiographic diagnosis of left ventricular hypertrophy (LVH) has been centered on improving the diagnostic sensitivity and specificity of the method, using criteria whose precise relationship to increased left ventricular mass are not established. Although the electrocardiogram (ECG) has been displaced to a secondary role in the prediction of left ventricular mass, ECG/LVH has been shown to be a strong predictor of morbidity and early mortality. There are strong clues that each of the parameters in ECG/LVH is related to cardiac contractility and ejection. It is suggested that research be redirected to an exploration of these relationships and predicted that this will lead to both a better understanding of this venerable tool and an improvement in its usefulness to the clinician and patient.

ECG myocardial scar quantification predicts reverse left ventricular remodeling and survival after cardiac resynchronization therapy implantation: A retrospective pilot study.

INTRODUCTION Electrocardiographic (ECG) LV scar quantification may improve prediction of CRT response. METHODS AND RESULTS Data were abstracted in 76 patients who underwent a first CRT implantation at 2 US centers. Selvester QRS scar quantification was performed using the LBBB modified QRS scoring method. Seven clinical variables previously associated with reverse LV remodeling (RLVR) and QRS score were included in logistic regression analysis. Survival was compared across QRS score quartiles using Kaplan-Meier curves. RLVR occurred more frequently in patients with QRS score ≤ 5 (63%) than QRS score>5 (22%), (OR=5.83, 95% CI=2.11-16.07). After adjustment for clinical variables using logistic regression, QRS score>5 predicted RLVR (Chi-square=20.3, P=0.005, AUC=0.782). Patients in the lowest quartile of QRS score (<4) had improved survival compared to patients in the other QRS score quartiles (P=0.037). CONCLUSION ECG quantified LV scar predicts RLVR and long-term survival in patients with LBBB undergoing CRT implantation.

Hemiazygous Coil Placement for High-Defibrillation Thresholds in a Patient with a Right-Sided Implantable Cardioverter Defibrillator

A 41‐year‐old man underwent implantation of a right‐sided implantable cardioverter defibrillator after removal of an infected left‐sided system. Defibrillation threshold (DFT) testing on the right‐sided system failed to convert ventricular fibrillation at maximum device output (35 J) compared with a DFT of less than 15 J on the previous left‐sided system. A single‐coil lead was selectively placed into the hemiazygous vein, which courses leftward of the spine in a posterior‐anterior projection, resulting in an improved shocking vector and reduction in DFTs to less than 25 J. (PACE 2012; 35:e10–e12)

Exercise training and pacing status in patients with heart failure: results from HF-ACTION.

BACKGROUND We sought to determine if outcomes with exercise training in heart failure (HF) vary according to ventricular pacing type. METHODS AND RESULTS Heart Failure: A Controlled Trial Investigating Outcomes of Exercise Training (HF-ACTION) randomized 2,331 outpatients with HF and left ventricular ejection fraction ≤35% to usual care plus exercise training or usual care alone. We examined the relationship between outcomes and randomized treatment according to ventricular pacing status with the use of Cox proportional hazards modeling. In HF-ACTION 1,118 patients (48%) had an implanted cardiac rhythm device: 683 with right ventricular (RV) and 435 with biventricular (BiV) pacemakers. Patients with pacing devices were older, more frequently white, and had lower peak VO2 (P < .001 for all). Peak VO2 improved similarly with training in groups with and without pacing devices. The primary composite end point-all-cause death or hospitalization-was reduced only in patients randomized to exercise training without a device (hazard ratio [HR] 0.79, 95% confidence interval [CI] 0.67-0.93 [P = .004]; RV lead: HR 1.04, 95% CI 0.84-1.28 [P = .74]; BiV pacing: HR 1.05, 95% CI 0.82-1.34 [P = .72]; interaction P = .058). CONCLUSIONS Exercise training may improve exercise capacity in patients with implanted cardiac devices. However, the apparent beneficial effects of exercise on hospitalization or death may be attenuated in patients with implanted cardiac devices and requires further study.

Cardiac Resynchronization Therapy in Patients with Renal Dysfunction: Keep Calm and Carry On

Renal insufficiency is present in more than half of patients with heart failure (HF). The causes of renal dysfunction in HF are multifactorial: impaired left ventricular (LV) function leads to increases in right atrial pressure and venous congestion while poor forward flow results in a release of neurohormones and natriuretic peptides, perpetuating a vicious cycle of worsening renal function referred to as the “cardiorenal syndrome.”1 In patients with cardiomyopathy, the presence of renal dysfunction is associated with excess mortality.2 Each 10 mL/min/1.73 m2 decrease in the estimated glomerular filtration rate (eGFR) is associated with a 17% increase in the risk of sudden cardiac death (SCD).3 At the extreme, patients with end-stage renal disease carry a 6to 9-fold higher risk of SCD. Data regarding the effectiveness of implantable cardioverter defibrillator (ICD) therapy in patients with renal insufficiency are largely lacking as patients with moderate to severe kidney disease were excluded from most of these trials. In MADIT-II, which did include and report on outcomes in patients with renal insufficiency, no survival advantage with ICD was seen in patients with an eGFR < 35 mL/min/1.73 m2.3 Cardiac resynchronization therapy (CRT) may provide additional benefit to patients with renal insufficiency beyond ICD therapy alone. Correction of electrical and mechanical dyssynchrony with biventricular pacing results in improved cardiac hemodynamics and function. CRT has been shown to result in an improvement in renal function in patients who also demonstrate evidence of reverse remodeling by echocardiography.4 Conversely, patients who fail to respond to CRT may show a significant and progressive decline in renal function. In the CARE-HF (Cardiac Resynchronization-Heart Failure) trial, CRT-pacing (CRT-P) was compared with no device treatment in patients with symptomatic HF, severe LV dysfunction, and evidence of ventricular dyssynchrony.5 In

Symptom challenges after atrial fibrillation ablation

Background: It is unclear what symptom challenges occur during the recovery phase after atrial fibrillation (AF) ablation. Objectives: This longitudinal pilot study explored the patient perspective of the first six months following an AF ablation. Methods: Telephone interviews and questionnaires were used with 20 patients at baseline, at 1, 3, and 6 months after AF ablation. Telephone interview data were analyzed using content analysis. Longitudinal outcomes were analyzed using repeated measures analysis of variance (ANOVA). Results: Mean age was 65 ± 7 years and the sample was 55% female. The severity and duration of fatigue was the most concerning symptom. Patient expectations differed from providers’ expectations. Recovery was a much slower process than patients expected. Conclusions: Patients struggled to manage symptoms after AF ablation. A more accurate understanding of the symptom challenges following AF ablation could lead to development of more realistic education to improve patient self‐management.

Obstructive sleep apnea is associated with increased rotor burden in patients undergoing focal impulse and rotor modification guided atrial fibrillation ablation

Aims To assess whether obstructive sleep apnea (OSA) was associated with increased rotor burden among atrial fibrillation (AF) patients. Methods and results We studied 33 consecutive patients who were scheduled for focal impulse and rotor modulation (FIRM) ablation at our institution to describe the mapping, ablation, and outcomes, among patients with and without OSA. Patients underwent biatrial FIRM mapping in AF with ablation of stable rotors in addition to conventional ablation lesion sets. Differences between groups were tested with students t-tests and Fishers exact tests, as appropriate. Survival analyses were performed using the Kaplan-Meier method. Twelve of the 33 (36%) patients had OSA and 8 (66%) used continuous positive airway pressure ventilation (CPAP). Obstructive sleep apnea patients had a higher body mass index (BMI) (33.6 vs. 28.8 kg/m2, P = 0.01) and were more commonly on beta blockers (67% vs. 29%, P = 0.03) but were otherwise similar regarding baseline characteristics, medication use, and prior AF treatments, including antiarrhythmic drugs and prior ablation. Focal impulse and rotor modulation mapping demonstrated increased rotor burden in the OSA patients (2.6 ± 0.9 vs. 2.0 ± 1.0, P =0.03). The increased rotor burden was more evident in the right atrium (RA) (1.0 ± 0.7 vs. 0.5 ± 0.7, P =0.04 compared with left atrium (1.7 ± 0.8 vs. 1.4 ± 0.7, P = 0.15). There was no correlation between BMI and total number of rotors (r = 0.0961, P = 0.59). Among the population of patients with OSA, CPAP therapy was associated with a lower number of RA rotors (0.8 ± 0.7 vs. 1.5 ± 0.6, P = 0.05) but no significant difference in overall rotors (P = 0.33). Conclusion Obstructive sleep apnea patients demonstrate increased rotor prevalence, driven predominantly by an increase in RA rotors. CPAP therapy was associated with fewer RA rotors.