Peak frequency mapping of atypical atrial flutter.

INTRODUCTION: Peak frequency (PF) mapping is a novel method that may identify critical portions of myocardial substrate supporting reentry. The aim of this study was to describe and evaluate PF mapping combined with omnipolar voltage mapping in the identification of critical isthmuses of left atrial (LA) atypical flutters. METHODS AND RESULTS: LA omnipolar voltage and PF maps were generated in flutter using the Advisor HD-Grid catheter (Abbott) and EnSite Precision Mapping System (Abbott) in 12 patients. Normal voltage was defined as ≥0.5 mV, low-voltage as 0.1-0.5 mV, and scar as <0.1 mV. PF distributions were compared with ANOVA and post hoc Tukey analyses. The 1 cm radius from arrhythmia termination was compared to global myocardium with unpaired t-testing. The mean age was 65.8 ± 9.7 years and 50% of patients were female. Overall, 34 312 points were analyzed. Atypical flutters most frequently involved the mitral isthmus (58%) or anterior wall (25%). Mean PF varied significantly by myocardial voltage: normal (335.5 ± 115.0 Hz), low (274.6 ± 144.0 Hz), and scar (71.6 ± 140.5 Hz) (p < .0001 for all pairwise comparisons). All termination sites resided in low-voltage regions containing intermediate or high PF. Overall, mean voltage in the 1 cm radius from termination was significantly lower than the remaining myocardium (0.58 vs. 0.95 mV, p < .0001) and PF was significantly higher (326.4 vs. 245.1 Hz, p < .0001). CONCLUSION: Low-voltage, high-PF areas may be critical targets during catheter ablation of atypical atrial flutter.

Use of Ripple mapping to enhance localization and ablation of outflow tract premature ventricular contractions.

INTRODUCTION: Accurate localization of septal outflow tract premature ventricular contractions (PVCs) is often difficult due to frequent mid-myocardial or protected origin. Compared with traditional activation mapping, CARTO Ripple mapping provides visualization of all captured electrogram data without assignment of a specific local activation time and thus may enhance PVC localization. METHODS: Electroanatomic maps for consecutive catheter ablation procedures for septal outflow tract PVCs (July 2018-December 2020) were analyzed. For each PVC, we identified the earliest local activation point (EA), defined by the point of maximal -dV/dt in a simultaneously recorded unipolar electrogram, and the earliest Ripple signal (ERS), defined as the earliest point at which three grouped simultaneous Ripple bars appeared in late diastole. Immediate success was defined as full suppression of the clinical PVC. RESULTS: Fifty-seven unique PVCs in 55 procedures were included. When ERS and EA were in the same chamber (RV, LV, or CS), the odds ratio for the successful procedure was 13.1 (95% confidence interval [CI] 2.2-79.9, p = .005). Discordance between sites was associated with a higher likelihood of needing multi-site ablation (odds ratio [OR] 7.9 [1.4-4.6; p = .020]). Median EA-ERS distance in successful versus unsuccessful cases was 4.6 mm (interquartile range 2.9-8.5) versus 12.5 mm (7.8-18.5); (p = .020). CONCLUSION: Greater EA-ERS concordance was associated with higher odds of single-site PVC suppression and successful septal outflow tract PVC ablation. Visualization of complex signals via automated Ripple mapping may offer rapid localization information complementary to local activation mapping for PVCs of mid-myocardial origin.

Association of leadless pacing with ventricular and valvular function.

BACKGROUND: Traditional transvenous pacemakers are associated with worsening tricuspid valve function due to lead-related leaflet impingement, as well as ventricular dysfunction related to electromechanical dyssynchrony from chronic right ventricular (RV) pacing. The association of leadless pacing with ventricular and valvular function has not been well established. We aimed to assess the association of leadless pacemaker placement with changes in valvular regurgitation and ventricular function. METHODS AND RESULTS: Echocardiographic features before and after leadless pacemaker implant were analyzed in consecutive patients who received a leadless pacemaker with pre- and postprocedure echocardiography at Duke University Hospital between November 2014 and November 2019. Valvular regurgitation was graded ordinally from 0 (none) to 3 (severe). Among 54 patients, the mean age was mean age was 70.1 ± 14.3 years, 24 (44%) were women, and the most frequent primary pacing indication was complete heart block in 24 (44%). The median RV pacing burden was 45.4 (interquartile range [IQR] 3.5-97.0). On echocardiogram performed 8.9 months (IQR 4.5-14.5) after implant, there was no change in the average severity of tricuspid regurgitation (mean change 0.07 ± 1.15, p = .64) from pre-procedure echocardiogram. We observed a decrease in the average left ventricular ejection fraction (LVEF) (52.3 ± 9.3 to 47.9 ± 12.1, p = .0019) and tricuspid annular plane systolic excursion (TAPSE) (1.8 ± 0.6 to 1.6 ± 0.4, p = .0437). Thirteen patients (24%) had absolute drop in LVEF of ≥10%. CONCLUSION: We did not observe short term worsening valvular function in patients with leadless pacemakers. However, consistent with the pathophysiologic impact of RV pacing, leadless pacing was associated with a reduction in biventricular function.

Left Atrial Appendage Occlusion Versus Oral Anticoagulation in Atrial Fibrillation : A Decision Analysis.

BACKGROUND: Left atrial appendage occlusion (LAAO) is a potential alternative to oral anticoagulants in selected patients with atrial fibrillation (AF). Compared with anticoagulants, LAAO decreases major bleeding risk, but there is uncertainty regarding the risk for ischemic stroke compared with anticoagulation. OBJECTIVE: To determine the optimal strategy for stroke prevention conditional on a patient's individual risks for ischemic stroke and bleeding. DESIGN: Decision analysis with a Markov model. DATA SOURCES: Evidence from the published literature informed model inputs. TARGET POPULATION: Women and men with nonvalvular AF and without prior stroke. TIME HORIZON: Lifetime. PERSPECTIVE: Clinical. INTERVENTION: LAAO versus warfarin or direct oral anticoagulants (DOACs). OUTCOME MEASURES: The primary end point was clinical benefit measured in quality-adjusted life-years. RESULTS OF BASE-CASE ANALYSIS: The baseline risks for stroke and bleeding determined whether LAAO was preferred over anticoagulants in patients with AF. The combined risks favored LAAO for higher bleeding risk, but that benefit became less certain at higher stroke risks. For example, at a HAS-BLED score of 5, LAAO was favored in more than 80% of model simulations for CHA2DS2-VASc scores between 2 and 5. The probability of LAAO benefit in QALYs (>80%) at lower bleeding risks (HAS-BLED score of 0 to 1) was limited to patients with lower stroke risks (CHA2DS2-VASc score of 2). Because DOACs carry lower bleeding risks than warfarin, the net benefit of LAAO is less certain than that of DOACs. RESULTS OF SENSITIVITY ANALYSIS: Results were consistent using the ORBIT bleeding score instead of the HAS-BLED score, as well as alternative sources for LAAO clinical effectiveness data. LIMITATION: Clinical effectiveness data were drawn primarily from studies on the Watchman device. CONCLUSION: Although LAAO could be an alternative to anticoagulants for stroke prevention in patients with AF and high bleeding risk, the overall benefit from LAAO depends on the combination of stroke and bleeding risks in individual patients. These results suggest the need for a sufficiently low stroke risk for LAAO to be beneficial. The authors believe that these results could improve shared decision making when selecting patients for LAAO. PRIMARY FUNDING SOURCE: None.

Electrocardiographic parameters associated with pacemaker induced cardiomyopathy.

BACKGROUND: Chronic right ventricular (RV) pacing can induce left ventricular (LV) dyssynchrony and cause pacemaker induced cardiomyopathy (PiCM). Identifying which patients are at risk for PiCM is limited. METHODS: Patients receiving RV-only permanent pacemakers (PPMs) at Duke University Medical Center between 2011 and 2017 who had normal baseline ejection fractions (EFs) were identified. Patients who developed a subsequent decrease in EF, died, or underwent cardiac resynchronization therapy, left ventricular assist device, or heart transplant without a competing cause were considered as the primary endpoint. Pre-PPM and post-PPM electrocardiograms (ECGs) were analyzed to extract scalar measurements including the lead one ratio (LOR) as well as advanced-ECG (A-ECG) features to identify predictors of PiCM. Traditional and penalized Cox regression were used to identify variables predictive of the primary endpoint. RESULTS: Pre-PPM ECGs were evaluated for 404 patients of whom 140 (35%) experienced the primary endpoint. Predictors included female sex (hazard ratio [HR] 1.14), a T' wave in V6 (HR 1.31), a P' wave in aVL (HR 0.88), and estimated glomerular filtration rate (HR 0.88). Post-PPM ECGs were evaluated for 228 patients for whom 94 (41%) experienced the primary endpoint. Predictors included female sex (HR 0.50), age (HR 1.06), and a history of congestive heart failure (HR 1.63). Neither LOR nor A-ECG parameters were strong predictors of the primary endpoint. CONCLUSIONS: Baseline and paced ECG data provide limited insight into which patients are at high risk for developing PiCM.

Leadless pacemaker implantation after lead extraction for cardiac implanted electronic device infection.

BACKGROUND: Cardiac implanted electronic device (CIED) pocket and systemic infection remain common complications with traditional CIEDs and are associated with high morbidity and mortality. Leadless pacemakers may be an attractive pacing alternative for many patients following complete hardware removal for a CIED infection by eliminating surgical pocket-related complications as well as lower risk of recurrent complications. OBJECTIVE: To describe use and outcomes associated with leadless pacemaker implantation following extraction of a CIED system due to infection. METHODS: Patient characteristics and postprocedural outcomes were described in patients who underwent leadless pacemaker implantation at Duke University Hospital between November 11, 2014 and November 18, 2019, following CIED infection and device extraction. Outcomes of interest included procedural complications, pacemaker syndrome, need for system revision, and recurrent infection. RESULTS: Among 39 patients, the mean age was 71 ± 17 years, 31% were women, and the most frequent primary pacing indication was complete heart block (64.1%) with 9 (23.1%) patients being pacemaker dependent at the time of Micra implantation. The primary organism implicated in the CIED infection was Staphylococcus aureus (43.6%). Nine of the 39 patients had a leadless pacemaker implanted before or on the same day as their extraction procedure, and the remaining 30 patients had a leadless pacemaker implanted after their extraction procedure. During follow-up (mean 24.8 ± 14.7 months) after leadless pacemaker implantation, there were a total of 3 major complications: 1 groin hematoma, 1 femoral arteriovenous fistula, and 1 case of pacemaker syndrome. No patients had evidence of recurrent CIED infection after leadless pacemaker implantation. CONCLUSIONS: Despite a prior CIED infection and an elevated risk of recurrent infection, there was no evidence of CIED infection with a mean follow up of over 2 years following leadless pacemaker implantation at or after CIED system removal. Larger studies with longer follow-up are required to determine if there is a long-term advantage to implanting a leadless pacemaker versus a traditional pacemaker following temporary pacing when needed during the periextraction period in patients with a prior CIED infection.

Implantable cardioverter-defibrillator lead revision following left ventricular assist device implantation.

INTRODUCTION: Lead dysfunction can lead to serious consequences including failure to treat ventricular tachycardia or fibrillation (VT/VF). The incidence and mechanisms of lead dysfunction following left ventricular assist device (LVAD) implantation are not well-described. We sought to determine the incidence, mechanisms, timing, and complications of right ventricular lead dysfunction requiring revision following LVAD implantation. METHODS: Retrospective observational chart review of all LVAD recipients with pre-existing implantable cardioverter-defibrillator (ICD) from 2009 to 2018 was performed including device interrogation reports, laboratory and imaging data, procedural reports, and clinical outcomes. RESULTS: Among 583 patients with an ICD in situ undergoing LVAD implant, the median (interquartile range) age was 62.5 (15.7) years, 21% were female, and the types of LVADs included HeartWare HVAD (26%), HeartMate II (52%), and HeartMate III (22%). Right ventricular lead revision was performed in 38 patients (6.5%) at a median (25th, 75th) of 16.4 (3.6, 29.2) months following LVAD. Mechanisms of lead dysfunction included macrodislodgement (n = 4), surgical lead injury (n = 4), recall (n = 3), insulation failure (n = 8) or conductor fracture (n = 7), and alterations in the lead-myocardial interface (n = 12). Undersensing requiring revision occurred in 22 (58%) cases. Clinical sequelae of undersensing included failure to detect VT/VF (n = 4) and pacing-induced torsade de pointes (n = 1). Oversensing occurred in 12 (32%) and sequelae included inappropriate antitachycardia pacing ([ATP], n = 8), inappropriate ICD shock (n = 6), and ATP-induced VT (n = 1). CONCLUSION: The incidence of right ventricular lead dysfunction following LVAD implantation is significant and has important clinical sequelae. Physicians should remain vigilant for lead dysfunction after LVAD surgery and test lead function before discharge.

Performance of a novel active fixation quadripolar left ventricular lead for cardiac resynchronization therapy: Attain Stability Quad Clinical Study results.

INTRODUCTION: The Medtronic Attain Stability Quad lead is a quadripolar left ventricular (LV) lead with an active fixation helix assembly designed to fixate the lead within the coronary sinus and pace nonapical regions of the LV. The primary objective of this study was to determine the safety and effectiveness of this novel active fixation quadripolar LV lead. METHODS: Patients with standard indications for cardiac resynchronization therapy (CRT) were enrolled. All patients were followed at 3 and 6 months post-implant and every 6 months thereafter until study closure. Pacing capture thresholds (PCTs) were measured at implant and each follow-up and adverse events (AEs) were recorded upon occurrence. RESULTS: Of the 440 patients who underwent implant procedures, placement of the Attain Stability Quad lead was successful in 426 (96.8%). LV lead-related complications occurred in 10 patients (2.3%), including LV lead dislodgement in three patients (0.7%). The percentage of patients with at least one LV pacing vector with a PCT ≤2.5 V at a 6-month follow-up was 96.3%. The LV lead was successfully fixated to the prespecified pacing location in 97.4% of cases. CONCLUSIONS: This large, multinational study of the Attain Stability Quad lead demonstrated a high rate of implant success with a low complication rate. The active fixation mechanism allowed precise placement of the pacing electrodes at the desired target region with good PCTs and a very low dislodgement rate.

VVI pacing with normal QRS duration and ventricular function: MOST trial findings relevant to leadless pacemakers.

BACKGROUND: Leadless pacemakers (LPs) provide ventricular pacing without the risks associated with transvenous leads and device pockets. LPs are appealing for patients who need pacing, but do not need defibrillator or cardiac resynchronization therapy. Most implanted LPs provide right ventricular pacing without atrioventricular synchrony (VVIR mode). The Mode Selection Trial in Sinus Node Dysfunction (MOST) showed similar outcomes in patients randomized to dual-chamber (DDDR) versus ventricular pacing (VVIR). We compared outcomes by pacing mode in LP-eligible patients from MOST. METHODS: Patients enrolled in the MOST study with an left ventricular ejection fraction (LVEF) >35%, QRS duration (QRSd) <120 ms and no history of ventricular arrhythmias or prior implantable cardioverter defibrillators were included (LP-eligible population). Cox proportional hazards models were used to test the association between pacing mode and death, stroke or heart failure (HF) hospitalization and atrial fibrillation (AF). RESULTS: Of the 2010 patients enrolled in MOST, 1284 patients (64%) met inclusion criteria. Baseline characteristics were well balanced across included patients randomized to DDDR (N = 630) and VVIR (N = 654). Over 4 years of follow-up, there was no association between pacing mode and death, stroke or HF hospitalization (VVIR HR 1.28 [0.92-1.75]). VVIR pacing was associated with higher risk of AF (HR 1.32 [1.08-1.61], P = .007), particularly in patients with no history of AF (HR 2.38 [1.52-3.85], P < .001). CONCLUSION: In patients without reduced LVEF or prolonged QRSd who would be eligible for LP, DDDR, and VVIR pacing demonstrated similar rates of death, stroke or HF hospitalization; however, VVIR pacing significantly increased the risk of AF development.

Catheter ablation of atrial fibrillation in cardiac amyloidosis.

BACKGROUND: Cardiac amyloidosis is a progressive infiltrative disease involving deposition of amyloid fibrils in the myocardium and cardiac conduction system that frequently manifests with heart failure (HF) and arrhythmias, most frequently atrial fibrillation (AF), atrial flutter (AFL), and atrial tachycardia (AT). METHODS: We performed an observational retrospective study of patients with a diagnosis of cardiac amyloid who underwent catheter ablation at our institution between January 1, 2011 and December 1, 2018. Patient demographics, procedural characteristics, and outcomes were determined by manual chart review. RESULTS: A total of 13 catheter ablations were performed over the study period in patients with cardiac amyloidosis, including 10 AT/AF/AFL ablations and three atrioventricular nodal ablations. Left ventricular ejection fraction was lower at the time of AV node ablation than catheter ablation of AT/AF/AFL (23% vs 40%, P = .003). Cardiac amyloid was diagnosed based on the results of preablation cardiac MRI results in the majority of patients (n = 7, 70%). The HV interval was prolonged at 60 ± 15 ms and did not differ significantly between AV nodal ablation patients and AT/AF/AFL ablation patients (69 ± 18 ms vs 57 ± 14 ms, P = .36). The majority of patients undergoing AT/AF/AFL ablation had persistent AF (n = 7, 70%) and NYHA class II (n = 5, 50%) or III (n = 5, 50%) HF symptoms, whereas patients undergoing AV node ablation were more likely to have class IV HF (n = 2, 66%, P = .014). Arrhythmia-free survival in CA patients after catheter ablation of AT/AF/AFL was 40% at 1 year and 20% at 2 years. CONCLUSIONS: Catheter ablation of AT/AF/AFL may be a feasible strategy for appropriately selected patients with early to mid-stage CA, whereas AV node ablation may be more appropriate in patients with advanced-stage CA.

Patient selection, pacing indications, and subsequent outcomes with de novo leadless single-chamber VVI pacing.

AIMS: Patient selection is a key component of securing optimal patient outcomes with leadless pacing. We sought to describe and compare patient characteristics and outcomes of Micra patients with and without a primary pacing indication associated with atrial fibrillation (AF) in the Micra IDE trial. METHODS AND RESULTS: The primary outcome (risk of cardiac failure, pacemaker syndrome, or syncope related to the Micra system or procedure) was compared between successfully implanted patients from the Micra IDE trial with a primary pacing indication associated with AF or history of AF (AF group) and those without (non-AF group). Among 720 patients successfully implanted with Micra, 228 (31.7%) were in the non-AF group. Reasons for selecting VVI pacing in non-AF patients included an expectation for infrequent pacing (66.2%) and advanced age (27.2%). More patients in the non-AF group had a condition that precluded the use of a transvenous pacemaker (9.6% vs. 4.7%, P = 0.013). Atrial fibrillation patients programmed to VVI received significantly more ventricular pacing compared to non-AF patients (median 67.8% vs. 12.6%; P < 0.001). The overall occurrence of the composite outcome at 24 months was 1.8% with no difference between the AF and non-AF groups (hazard ratio 1.36, 95% confidence interval 0.45-4.2; P = 0.59). CONCLUSION: Nearly one-third of patients selected to receive Micra VVI therapy were for indications not associated with AF. Non-AF VVI patients required less frequent pacing compared to patients with AF. Risks associated with VVI therapy were low and did not differ in those with and without AF.

Predicting atrial fibrillation recurrence after ablation in patients with heart failure: Validity of the APPLE and CAAP-AF risk scoring systems.

BACKGROUND: Compared with medical therapy, catheter ablation of atrial fibrillation (AF) in patients with heart failure (HF) improves cardiovascular outcomes. Risk scores (CAAP-AF and APPLE) have been developed to predict the likelihood of AF recurrence after ablation, have not been validated specifically in patients with AF and HF. METHODS: We analyzed baseline characteristics, risk scores, and rates of AF recurrence 12 months postablation in a cohort of 230 consecutive patients with AF and HF undergoing PVI in the Duke Center for Atrial Fibrillation registry from 2009-2013. RESULTS: During a follow-up period of 12 months, 76 of 230 (33%) patients with HF experienced recurrent AF after ablation. The median APPLE and CAAP-AF scores were 1.5 ([Q1, Q3]: [1.0, 2.0]) and 4.0 ([Q1, Q3]: [3.0, 5.0]), respectively and were not different from those patients with and without recurrent AF. Freedom from AF was not different according to APPLE and CAAP-AF scores. Discrimination for recurrent AF with the CAAP-AF score was modest with a C-statistic of 0.60 (95% CI 0.52-0.67). Discrimination with the APPLE score was similarly modest, with a C-statistic of 0.54 (95% CI: 0.47-0.62). CONCLUSIONS: Validated predictive risk scores for recurrent AF after catheter ablation exhibit limited predictive ability in cohorts of AF and HF. Additional tools are needed to facilitate risk stratification and patient selection for AF ablation in patients with concomitant HF.

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 student's t-tests and Fisher's 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.

Catheter ablation for ventricular tachycardia in patients with an implantable cardioverter defibrillator (CALYPSO) pilot trial.

INTRODUCTION: We conducted this pilot randomized clinical trial to determine the feasibility of a large clinical trial aimed at testing whether early use of catheter ablation of ventricular tachycardia (VT) is superior to antiarrhythmic medications at reducing mortality. METHODS AND RESULTS: Patients were enrolled at 4 sites if they had ischemic heart disease, an implantable cardioverter defibrillator (ICD), and received ≥1 ICD shock or ≥3 antitachycardia pacing therapies for VT. Patients were randomized to 2 arms: (1) antiarrhythmic medication (n = 14) and (2) catheter ablation (n = 13); patients were followed at 3 and 6 months. Endpoints included recurrent VT, time to first ICD therapy for VT, and death. Of 243 screened patients, 27 were enrolled. Main reasons for screen failures were: (1) patient was already on an antiarrhythmic medication (88 [41%]), (2) VT due to a reversible cause (23 [11%]), and (3) incessant VT (20 [9%]). Fourteen patients had recurrent VT, 8 (62%) in the ablation arm and 6 (43%) in the antiarrhythmic medication arm. Median time to recurrent VT was 75 days (25th, 75th: 51, 89) in the ablation arm and 57 days (30, 145) in the antiarrhythmic arm. Four patients died, 2 in each arm. CONCLUSION: This clinical trial shows that most patients in clinical practice have already failed antiarrhythmic drug therapy before catheter ablation is considered, and the VT recurrence rates and death in these patients are high. For a large clinical trial to be feasible, factors limiting early consideration of catheter ablation need to be identified and addressed.

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.

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.

Immediate mechanical effects of acute left bundle branch block by speckle tracked strain.

INTRODUCTION: Left bundle branch block (LBBB) is a known complication of transcatheter aortic valve replacement (TAVR) and has been shown to predict worsened outcomes in TAVR patients. A regional longitudinal strain pattern, termed the "classic" pattern of left ventricular (LV) dyssynchrony, which is thought to be due to LBBB, is highly predictive of response to cardiac resynchronization therapy. Whether LBBB causes this "classic" pattern is not known. METHODS: We retrospectively studied patients undergoing TAVR who also underwent pre- and post-TAVR strain analysis to determine if the "classic" pattern arose in those who developed TAVR-induced true LBBB. After removing patients with baseline conduction abnormalities or insufficient studies 9 patients had sufficient data for analysis. Six patients developed LBBB after TAVR and 3 patients did not develop LBBB after TAVR. ECGs were analyzed for the new onset of LBBB after TAVR. Global longitudinal strain (GLS) and regional longitudinal strain patterns were analyzed for changes between pre- and immediately post-TAVR examinations. RESULTS: Patients who did not develop LBBB showed no significant changes in their regional longitudinal strain pattern. Those patients who did develop LBBB showed significant increase in their difference of time-to-onset of contraction between the septal and lateral walls post-TAVR (22 ± 14 ms vs 111 ± 49 ms; p=0.003) and in their difference of time-to-peak contraction between the septal and lateral walls post-TAVR (63 ± 56 ms vs 133 ± 46 ms; p=0.002). Early lateral wall pre-stretch and delayed lateral wall peak contraction emerged in all patients with LBBB but early septal peak contraction meeting the established criteria was present in only one patient. DISCUSSION: The onset of LBBB led to acute, measurable changes in the regional longitudinal strain pattern consisting of early lateral wall pre-stretch and delayed lateral wall peak contraction. These represent 2 of the 3 findings in the "classic" pattern of LV dyssynchrony. Early termination of septal wall contraction meeting established criteria was not routinely found. Time and/or other factors may be required to develop the full "classic" pattern.

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.