Tracy Webster

Atrioventricular nodal ablation predicts survival benefit in patients with atrial fibrillation receiving cardiac resynchronization therapy

BACKGROUND Cardiac resynchronization therapy (CRT) benefits patients with advanced heart failure. The role of atrioventricular nodal (AVN) ablation in improving CRT outcomes, including survival benefit in CRT recipients with atrial fibrillation, is uncertain. OBJECTIVE The purpose of this study was to assess the impact of AVN ablation on clinical and survival outcomes in a large atrial fibrillation and heart failure population that met the current indication for CRT and to determine whether AVN ablation is an independent predictor of survival in CRT recipients. METHODS Of 154 patients with atrial fibrillation who received CRT-D, 45 (29%) underwent AVN ablation (+AVN-ABL group), whereas 109 (71%) received drug therapy for rate control during CRT (-AVN-ABL group). New York Heart Association (NYHA) class, electrocardiogram, and echocardiogram were assessed before and after CRT. Survival data were obtained from the national death and location database (Accurint). RESULTS CRT comparably improved left ventricular ejection fraction (8.1% +/- 10.7% vs 6.8% +/- 9.6%, P = .49) and left ventricular end-diastolic diameter (-2.1 +/- 5.9 mm vs -2.1 +/- 6.7 mm, P = .74) in both +AVN-ABL and -AVN-ABL groups. Improvement in NYHA class was significantly greater in the +AVN-ABL group than in -AVN-ABL group (-0.7 +/- 0.8 vs -0.4 +/- 0.8, P = .04). Survival estimates at 2 years were 96.0% (95% confidence interval [CI] 88.6%-100%) for +AVN-ABL group and 76.5% (95% CI 68.1%-85.8%) for-AVN-ABL group (P = .008). AVN ablation was independently associated with survival benefit from death (hazard ratio [HR] 0.13, 95% CI 0.03-0.58, P = .007) and from combined death, heart transplant, and left ventricular assist device (HR 0.19, 95% CI 0.06-0.62, P = .006) after CRT. CONCLUSION Among patients with atrial fibrillation and heart failure receiving CRT, AVN ablation for definitive biventricular pacing provides greater improvement in NYHA class and survival benefit. Larger-scale randomized trials are needed to assess the clinical and survival outcomes of this therapy.

Upgrade and de novo cardiac resynchronization therapy: Impact of paced or intrinsic QRS morphology on outcomes and survival

BACKGROUND Cardiac resynchronization therapy (CRT) improves outcomes in patients with left bundle branch block (LBBB), but the benefits of CRT in patients with other QRS morphologies or previous pacing are uncertain. OBJECTIVE The purpose of this study was to describe outcomes in patients with prior right ventricular pacing and non-LBBB morphologies. METHODS We studied 505 patients who underwent de novo CRT (n = 338) or CRT upgrade (n = 167). De novo patients were categorized by underlying QRS morphology: LBBB (67%), right bundle branch block (RBBB; 11%), intraventricular conduction delay (IVCD; 13%), and QRS <120 ms (9%). Upgrade patients were categorized by the percentage of previous ventricular pacing. RESULTS Patients were followed for death over a median of 2.6 years (interquartile range 1.6-4.0). New York Heart Association (NYHA) functional class and echocardiographic improvements were similar in de novo and upgrade patients. However, within the de novo group, NYHA improvements were less in patients with RBBB (0.3 +/- 0.8; P = .014) or IVCD (0.2 +/- 0.7; P = .001) than in those with LBBB (0.7 +/- 0.8). These patients had less left ventricular functional improvement as well. Survival was comparable after de novo versus upgrade CRT (61% vs 63% at 4 years; P = .906). No clinical or survival differences were noted in upgrade patients based on the percentage of previous pacing. However, survival in de novo CRT recipients with RBBB (32%) was lower than in those with LBBB (66%; P <.001), and RBBB independently predicted death (hazard ratio 3.5, confidence interval 1.9-6.5; P <.001). CONCLUSION RBBB and IVCD result in less clinical improvement or worsened survival after CRT. Additional selection criteria may be beneficial in identifying potential responders with RBBB, IVCD, or narrow QRS.

Differential outcome of cardiac resynchronization therapy in ischemic cardiomyopathy and idiopathic dilated cardiomyopathy.

BACKGROUND Cardiac resynchronization therapy (CRT) is a therapy of proven benefit in patients with advanced heart failure. Identifying potential responders remains challenging, and whether the etiology of the heart failure is related to the potential hemodynamic benefit and long-term outcome of CRT is unclear. OBJECTIVE The purpose of this study was to evaluate whether heart failure etiology (ischemic cardiomyopathy [ICM] vs nonischemic dilated cardiomyopathy [DCM]) was associated with CRT outcome and implantable cardioverter-defibrillator (ICD) shocks. METHODS The study included 503 CRT recipients (CRT-D 90%) in a longitudinal CRT database: ICM (n = 312) and DCM (n = 191). Clinical variables and echocardiographic measures preimplant and postimplant were collected. Actuarial survival and ICD therapy data were assessed with Kaplan-Meier curve and log rank tests. RESULTS Pre-CRT, ICM patients were older and had higher creatinine levels (P <.001). At median follow-up of 7.1 months, the DCM group experienced greater improvement in left ventricular ejection fraction (8.3% ± 10% vs 6.2% ± 10%, P = .05) and left ventricular end-diastolic volumes than did those with ICM (-28%.4 ± 53 mL vs -15.3 ± 46 mL, P = .024). Survival estimates at 4 years were 55% for ICM and 77% for DCM groups (P <.001), respectively, whereas no significant difference in the incidence of appropriate/inappropriate ICD shocks was observed. The ICM group remained at higher risk for death compared to the DCM group after controlling for preimplant variables (hazard ratio 1.6, 95% confidence interval 1.1-2.3, P = .008). CONCLUSION In response to CRT and in contrast to ICM, DCM patients experienced greater improvement in left ventricular systolic function and reverse remodeling while also sustaining a greater survival benefit.

Cardiac Sympathetic Reserve and Response to Cardiac Resynchronization Therapy

Background— The objective of the present study was to investigate the effect of cardiac resynchronization therapy (CRT) on cardiac autonomic function. Methods and Results— This prospective study included 45 consecutive patients with heart failure who received CRT devices with defibrillator and 20 age-matched, healthy control subjects. At baseline and 3 months and 6 months after CRT, we assessed New York Heart Association (NYHA) class, 6-minute walk distance, plasma sympathetic biomarker nerve growth factor, echocardiography, heart rate variability and cardiac presynaptic sympathetic function determined by iodine 123 metaiodobenzylguanidine scintigraphy. After CRT, NYHA class improved by 1 class (P<0.001), and left ventricular ejection fraction increased by 8% (P<0.001). Along with improvement in the standard deviation of all normal-to-normal R-R intervals (85.63±31.66 ms versus 114.79±38.99 ms; P=0.004) and the standard deviation of the averaged normal-to-normal R-R intervals (82.62±23.03 ms versus 100.50±34.87 ms; P=0.004), the delayed heart/mediastinum (H/M) ratio increased (1.82 [0.58] versus 1.97 [0.59]; P=0.03), whereas the mean (SD) H/M washout rate was reduced (48% [19%] versus 37% [22%]; P=0.01). Twenty-two of 45 study patients responded to CRT, with a reduction of left ventricular end-systolic volume index >15%. Compared with nonresponders, responders had a higher delayed H/M ratio (2.11 versus 1.48; P=0.003) and lower H/M washout rate (37% versus 62%; P=0.003) at baseline. Conclusions— CRT improved sympathetic function. Cardiac sympathetic reserve may be a marker for the reversibility of failing myocardial function.

Features and Outcomes of Patients Who Underwent Cardiac Device Deactivation

IMPORTANCE Little is known about patients who undergo cardiovascular implantable electronic device deactivation. OBJECTIVE To describe features and outcomes of patients who underwent cardiovascular implantable electronic device deactivation. DESIGN, SETTING, AND PARTICIPANTS Retrospective review of medical records of 150 patients at a tertiary academic medical center (Mayo Clinic, Rochester, Minnesota). EXPOSURE Cardiovascular implantable electronic device deactivation. MAIN OUTCOMES AND MEASURES Demographic and clinical data and information regarding advance directives, ethics consultations, palliative medicine consultations, and cardiovascular implantable electronic device deactivations. RESULTS Of the 150 patients (median age, 79 years; 67% were male), 149 (99%) had poor or terminal prognoses. Overall, 118 patients (79%) underwent deactivation of tachycardia therapies only, and 32 (21%) underwent deactivation of bradycardia therapies with or without tachycardia therapies (6 patients [4%] were pacemaker-dependent). Half of the deactivation requests (51%) were made by surrogates. A majority of deactivations (55%) were carried out by nurses. Although 85 patients (57%) had advance directives, only 1 mentioned the device in the directive. Ethics consultations occurred in 3 patients (2%) and palliative medicine consultations in 64 (43%). The proportions of patients who died within 1 month of device deactivation were similar for those who underwent deactivation of tachycardia therapies only and those who underwent deactivation of bradycardia therapies with or without tachycardia therapies (85% vs 94%; P = .37). CONCLUSIONS AND RELEVANCE Most requests for cardiovascular implantable electronic device deactivation were for implantable cardioverter-defibrillator-delivered tachycardia therapies only. Many of these requests were made by surrogates. Advance directives executed by patients with these devices rarely addressed device management. Regardless of device therapy, most patients died shortly after device deactivation. Hence, a device deactivation decision may reflect the seriousness of a given patients underlying illness. Patients with devices should engage in advance care planning to ensure that future care is consistent with their preferences.

Outcomes of cardiac resynchronization therapy in the elderly.

Octogenarians (>80 years) have been underrepresented in clinical trials of cardiac resynchronization therapy (CRT).

Right Parasternal Lead Placement Increases Eligibility for Subcutaneous Implantable Cardioverter Defibrillator Therapy in Adults With Congenital Heart Disease.

BACKGROUND The subcutaneous implantable cardioverter defibrillator (S-ICD) provides an attractive option for patients with congenital heart disease (CHD) in whom a transvenous defibrillator is contraindicated. Given the unusual cardiac anatomy and repolarization strain, the surface electrocardiogram (ECG) is frequently abnormal, potentially increasing the screen failure rate. METHODSANDRESULTS We prospectively screened 100 adult CHD patients regardless of the presence of clinical indication for ICD utilizing a standard left sternal lead placement, as well as a right parasternal position. Baseline patient and 12-lead ECG characteristics were examined to assess for predictors of screen failure. Average patient age was 48±14 years, average QRS duration was 134±37 ms, and 13 patients were pacemaker dependent. Using the standard left parasternal electrode position, 21 patients failed screening. Of these 21 patients with screen failure, 9 passed screening with the use of right parasternal electrode positioning, reducing screening failure rate from 21% to 12%. QT interval and inverted T wave anywhere in V2-V6 leads were found to be independent predictors of left parasternal screening failure (P=0.01 and P=0.04, respectively). CONCLUSIONS Utilization of both left and right parasternal screening should be used in evaluation of CHD patients for S-ICD eligibility. ECG repolarization characteristics were also identified as novel predictors of screening failure in this group. (Circ J 2016; 80: 1328-1335).

Long‐term Stability of Endocardial Left Ventricular Pacing Leads Placed via the Coronary Sinus

Background: Left ventricular endocardial pacing leads placed via the coronary sinus (CS) are increasingly implanted to achieve cardiac resynchronization therapy (CRT); however, the long‐term stability of these leads is unknown. We sought to determine the implant success and long‐term stability of CS leads in our single center experience.

Outcomes After Implantable Cardioverter-Defibrillator Generator Replacement for Primary Prevention of Sudden Cardiac Death.

Background—The effectiveness of implantable cardioverter-defibrillators (ICDs) for primary prevention of sudden death in patients with an ejection fraction (EF) ⩽35% and clinical heart failure is well established. However, outcomes after replacement of the ICD generator in patients with recovery of EF to >35% and no previous therapies are not well characterized. Methods and Results—Between 2001 and 2011, generator replacement was performed at 2 tertiary medical centers in 253 patients (mean age, 68.3±12.7 years; 82% men) who had previously undergone ICD placement for primary prevention but subsequently never received appropriate ICD therapy. EF had recovered to >35% in 72 of 253 (28%) patients at generator replacement. During median (quartiles) follow-up of 3.3 (1.8–5.3) years after generator replacement, 68 of 253 (27%) experienced appropriate ICD therapy. Patients with EF ⩽35% were more likely to experience ICD therapy compared with those with EF >35% (12% versus 5% per year; hazard ratio, 3.57; P=0.001). On multivariable analysis, low EF predicted appropriate ICD therapy after generator replacement (hazard ratio, 1.96 [1.35–2.87] per 10% decrement; P=0.001). Death occurred in 25% of patients 5 years after generator replacement. Mortality was similar in patients with EF ⩽35% and >35% (7% versus 5% per year; hazard ratio, 1.10; P=0.68). Atrial fibrillation (3.24 [1.63–6.43]; P<0.001) and higher blood urea nitrogen (1.28 [1.14–1.45] per increase of 10 mg/dL; P<0.001) were associated with mortality. Conclusions—Although approximately one fourth of patients with a primary prevention ICD and no previous therapy have EF >35% at the time of generator replacement, these patients continue to be at significant risk for appropriate ICD therapy (5% per year). These data may inform decisions on ICD replacement.

Effects of Tricuspid Valve Regurgitation on Outcome in Patients With Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) has a symptomatic and survival benefit for patients with heart failure (HF), but the percentage of nonresponders remains relatively high. The aims of this study were to assess the clinical significance of baseline tricuspid regurgitation (TR) or worsening TR after implantation of a CRT device on the response to therapy. This is a multicenter retrospective analysis of prospectively collected databases that includes 689 consecutive patients who underwent implantation of CRT. The patients were divided into groups according to baseline TR grade and according to worsening TR within 15 months after device implantation. Outcome was assessed by clinical and echocardiographic response within 15 months and by estimated survival for a median interquartile range follow-up time of 3.3 years (1.6, 4.6). TR worsening after CRT implantation was documented in 104 patients (15%). These patients had worse clinical and echocardiographic response to CRT, but worsening of TR was not a significant predictor of mortality (p = 0.17). According to baseline echocardiogram, 620 patients (90%) had some degree of TR before CRT implant. Baseline TR was an independent predictor of worse survival (p <0.001), although these patients had significantly better clinical and echocardiographic response compared with patients without TR. In conclusion, worsening of TR after CRT implantation is a predictor of worse clinical and echocardiographic response but was not significantly associated with increased mortality. Baseline TR is associated with reduced survival despite better clinical and echocardiographic response after CRT implantation.