CRT-defibrillator Implantation Research Articles

PO-707-07 SUDDEN CARDIAC DEATH AND APPROPRIATE DEFIBRILLATOR THERAPIES IN PATIENTS WITH IMPROVED EJECTION FRACTION >35%

Implantable cardioverter-defibrillators (ICDs) and CRT-defibrillator (CRT-D) improve survival in indicated patients with left ventricular ejection fraction (LVEF) less than 35%. Approximately 75% of patients with ICD implantation for primary prevention do not experience an appropriate ICD Tachyarrhythmia Therapy (ITT) in the initial generator lifespan. The role of continued arrhythmia monitoring and therapies(and need for generator change) in those with improved left ventricular ejection fraction(LVEF) is not well studied. Evaluation of rates of ITT and incidence of sudden cardiac death(SCD) among patients with improved LVEF>35% after defibrillator placement. A retrospective study of patients who underwent CRT-D and ICD implantation for primary prevention was done. Patients >18 years of age with ischemic(ICM) or non-ischemic cardiomyopathy(NICM) with an initial EF<35%, and who had an improvement in LVEF post-implantation were included. Patients whose LVEF remained <35% after implantation were excluded. We stratified the patients based on their improved EF, as 36-45%, 46-55%, and >55%, respectively. Of 337 patients evaluated, LVEF improved >35% in 79 patients. The mean age for the study population was 59 ± 15 years; NICM was the etiology for heart failure in 65.8% of patients. Over a median follow-up of 73 months, LVEF improved to 36-45% in 44 patients, 46-55% in 25 patients, and > 55% in 10 patients. Eight patients died during the follow-up; none from sudden cardiac death. Overall, patients with NICM received more appropriate therapies than ICM patients. Of 41 ITT events in NICM, 85% occurred in patients before EF improvement >35% (OR 8.0,95% CI: 1.12-56.79). 60% of the ITT events in ICM group were observed before EF improved >35%. Patients with NICM whose EF improved to >45 % were more likely to receive inappropriate than appropriate therapies. No events were reported in either NICM or ICM groups after LVEF improvement beyond 55%(Table 1). Among patients who receive an ICD for primary prevention, most events occurred before EF improvement. Among patients with NICM, patients experienced only inappropriate therapies once their EF improved >45%. Larger prospective studies are needed to evaluate the necessity of ICD generator change in this subgroup.

47CRT-D versus CRT-P: are we on the right track?

Abstract Introduction Implantable cardioverter defibrillators (ICD) and cardiac resynchronisation therapy (CRT) have both proven to reduce mortality in patients with heart failure (HF). However, randomised trials comparing CRT-pacemaker (CRT-P) vs CRT-defibrillator (CRT-D) are lacking. Understanding a patient’s primary mode of death is therefore important as this may guide the proper use of CRT systems and avoid risks that are associated with under -or overtreatment with an ICD. Purpose This study aims to analyse the mode of death and the occurrence of life-threatening ventricular arrhythmias (VAs) in patients who received a CRT-P or CRT-D. This may help in the future selection for an appropriate cardiac device in patients with HF. Methods Patients with HF undergoing CRT-P or CRT-D implantation in a tertiary hospital between January 2008 and December 2018 were retrospectively evaluated. CRT indications were in compliance with the ESC guidelines. The decision to implant CRT-D or CRT-P in primary prevention was left at the discretion of the treating physician but was based on ESC clinical guidance. Life threatening VAs (sustained ventricular tachycardia &amp;gt; 30s not requiring therapy or appropriate therapy for VAs) and mode of death were analysed. Results 511 patients were implanted with a CRT (CRT-D/CRT-P; n = 311/200) of which 410 (CRT-D/CRT-P; n= 245/165) were followed in our centre for 63,5 ± 38,1 months. Patients with CRT-P were older (77,6 ± 8,1 vs 66,8 ± 9,5 years; p &amp;lt;0,001), more often female (39,4 vs 26,9%; p 0,006), had more a non-ischaemic cause (61,2 vs 44,9%; p 0,001) and a significant higher comorbidity burden. They also received less treatment with neurohumoral blockers. Baseline LVEF was higher in the CRT-P group (33,1 ± 8,9 vs 28,0 ± 7,6%, p &amp;lt;0,001). 6 months follow-up showed a similar increase in LVEF in the CRT-P vs CRT-D group (+10,3 ± 9,6 vs +11,4 ± 10,8%, p 0,38). Main reasons to choose for CRT-P were RV-pacing induced cardiomyopathy (CMP) (26,1%), multiple comorbidities (18,8%), HF complicated by high degree AV block or AV junction ablation (18,2%), non-ischaemic CMP with suspected good CRT response (10,3%), age (7,3%), other (19,3%). 6/165 patients with CRT-P (3,6%), of which 5 were detected by remoted telemonitoring, vs 51/245 with CRT-D (20,8%) experienced episodes of life-threatening arrhythmias (p &amp;lt;0,001). All-cause mortality was higher in the CRT-P vs CRT-D group (36,4 vs 25,3%, p 0,005). However, the CRT-P group had a predominant non-cardiac mode of death (70,9 vs 43,3%, p &amp;lt;0,001). Death secondary to a tachyarrhythmic event was present in only 1 patient (1,7%) in the CRT-P group. Conclusions Guided by clinical parameters and presence of competitive non-cardiac causes of death, adequate decision between CRT-P or CRT-D implantation can be made. In our cohort, sudden cardiac death in the CRT-P group occurred only once. Remote monitoring is able to identify a subgroup of patients potentially benefiting from an upgrade from CRT-P to CRT-D.

P3800Defibrillation for right ventricular dysfunction - An echocardiographic method for therapy selection

Abstract Introduction Cardiac resynchronization therapy (CRT) is recommended for heart failure (HF) patients with left ventricular ejection fraction (LVEF) &lt;35% and QRS&gt;130 mseg. We aim to identify if baseline transthoracic echocardiographic (TTE) data can predict the need for defibrillation therapies in a primary prevention HF population referred for CRT implant. Methods We analyzed 119 consecutive HF patients in primary prevention referred for CRT implantation between 2004 and 2016. All patients underwent TTE before implantation. During a mean follow-up time of 58.4±33.9 months, all patients were evaluated with device interrogation every 6 months. In order to determine which parameters can predict sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) occurrence, a multivariate analysis was performed including previous medical history, baseline laboratorial, electro and echocardiographic data. Results We included 86.6% (n=106) males, mean age at implant 65.5±9.7 years. A CRT-defibrillator (CRT-D) was implanted in 82 (64.2%) patients and a VT or VF was documented in 16 patients (13.4%). Baseline characteristics are presented in the table. After multivariate analysis, baseline right ventricular dysfunction (defined as TAPSE≤18mm) was an independent predictor for VT or VF occurrence (OR=4.83, 95CI 1.67–6.25, p=0.002). Baseline characteristics VT/VF (n=16) No VT/VF (n=103) P-value Age (years, mean ± SD) 62,4±7,9 66,2±9,5 0,135 Female gender (n, %) 2 (12,5) 14 (15,1) 0,572 Ischemic cardiomyopathy (n, %) 7 (43,8) 21 (22,6) 0,073 NYHA III + IV (n, %) 13 (81,3) 76 (73,8) 0,984 QRS width (mseg, mean ± SD) 168,5±19,5 177,6±22,2 0,142 Atrial fibrillation (n, %) 5 (31,3) 17 (18,3) 0,089 LVEF (%, mean ± SD) 24,6±4,8 26,3±6,3 0,302 TAPSE (mm, mean ± SD) 14,9±4,9 17,9±4,3 0,034 PASP (mmHg, mean ± SD) 48,5±9,4 43,5±14,6 0,419 Mitral regurgitation (moderate or greater, n, %) 5 (31,3) 24 (28,9) 0,077 iVol (mL/m2, mean ± SD) 134,2±36,6 128,7±44,1 0,690 CRT-D implantation (n, %) 16 (100,0) 60 (64,5) 0,002 Conclusion In a real-world HF population, right ventricular dysfunction defined by echocardiography was an independent predictor for VT or VF occurrence. This may help more accurate patient selection for CRT-D implantation.

The role of interventricular conduction delay to predict clinical response with cardiac resynchronization therapy

Pacing at sites with late electrical activation or greater interventricular delay is associated with improvement in measures of cardiac resynchronization therapy (CRT) response, primarily reverse remodeling. However, little is known about whether such lead positions improve heart failure (HF) clinical outcomes. The purpose of this study was to assess the association between interventricular electrical delay and HF clinical outcomes. The Pacing Evaluation-Atrial SUpport Study was a multicenter randomized trial of patients undergoing CRT-defibrillator implantation. Interventricular delay was measured as the unpaced right ventricle-left ventricle (RV-LV) interval in sinus rhythm. The HF clinical composite score was the primary end point. In addition, the time to first HF hospitalization or death was measured and events were adjudicated by a blinded core laboratory. The cohort was divided at the median RV-LV interval into short (<67 ms) and long (≥67 ms) subgroups. In addition, receiver operating characteristic curves were constructed to identify the optimal cutoff of the RV-LV interval and spline analysis was performed to assess RV-LV interval as a continuous variable. A total of 1342 patients were included in this study. The clinical composite score at 1 year differed between groups, with more patients improving and fewer patients worsening in the long RV-LV group (P = .014). The time to first HF hospitalization or mortality also differed with a lower risk of an event in the long RV-LV group (hazard ratio 0.62; P = .002). Multivariate analysis showed that RV-LV time (hazard ratio 0.71; P = .038) and sex were independent predictors of this outcome. Baseline interventricular delay is a strong independent predictor of clinical response to CRT.

ECG score to predict ICD therapies in patients with nonischemic cardiomyopathy and primary prophylactic CRT-D

Recently published results of the DANISH study raise concerns, if primary prophylactic ICD implantations in patients with nonischemic cardiomyopathy (NICM) and severe reduced left ventricular ejection fraction (LVEF) should be performed without further risk stratification. There was no significant difference in the overall mortality of patients with or without ICD and CRT defibrillator (CRT-D) or CRT pacemaker (CRT-P), respectively. Clinical risk scores to identify patients with ischemic cardiomyopathy (ICM) who benefit most from an ICD have been recommended. The need for risk stratification systems concerning patients with NICM has been emphasized. A retrospective study of 434 consecutive patients with CRT-D implantation was performed. Patients with no regular follow-up at our institution (n= 132), secondary prophylactic ICD indication (n= 61), and upgrade to CRT (n= 95) were excluded. The occurrence of an adequate ICD therapy was defined as the endpoint. Left ventricular ejection fraction (LVEF), genesis of the cardiomyopathy as well as the modified Selvester ECG score (MSES) for evaluation of the left ventricular scar burden were documented among other characteristics. Within a median follow-up of 605 days, 24% of the patients experienced an adequate ICD therapy. These patients had significantly lower LVEF (20% vs. 23%), and the MSES was higher (7 vs. 3points). There was no significant difference in patients suffering from ICM vs NICM. Areceiver-operating-characteristic (ROC) analysis revealed asensitivity of 0.914 and aspecifity of 0.586 for MSES ≥4 to predict the occurrence of an ICD therapy. None of 35patients suffering from NICM with MSES <4 experienced an ICD therapy. The evaluation of the left ventricular scar burden using MSES can be useful for the decision between CRT-D and CRT-P in patients suffering from NICM.

Acute and Chronic Changes and Predictive Value of Tpeak-Tend for Ventricular Arrhythmia Risk in Cardiac Resynchronization Therapy Patients.

Background:Prolongation of the Tpeak-Tend (TpTe) interval as a measurement of transmural dispersion of repolarization (TDR) is an independent risk factor for chronic heart failure mortality. However, the cardiac resynchronization therapy's (CRT) effect on TDR is controversial. Therefore, this study aimed to evaluate CRTs acute and chronic effects on repolarization dispersion. Furthermore, we aimed to investigate the relationship between TpTe changes and ventricular arrhythmia.Methods:The study group consisted of 101 patients treated with CRT-defibrillator (CRT-D). According to whether TpTe was shortened, patients were grouped at immediate and 1-year follow-up after CRT, respectively. The echocardiogram index and ventricular arrhythmia were observed and compared in these subgroups.Results:For all patients, TpTe slightly increased immediately after CRT-D implantation, and then decreased at the 1-year follow-up (from 107 ± 23 to 110 ± 21 ms within 24 h, to 94 ± 24 ms at 1-year follow-up, F = 19.366, P < 0.001). No significant difference in the left ventricular reverse remodeling and ventricular tachycardia/ventricular fibrillation (VT/VF) episodes between the TpTe immediately shortened and TpTe immediately nonshortened groups. However, patients in the TpTe at 1-year shorten had a higher rate of the left ventricular (LV) reverse remodeling (65% vs. 44%, χ2 = 4.495, P = 0.038) and less VT/VF episodes (log-rank test, χ2 = 10.207, P = 0.001) compared with TpTe 1-year nonshortened group. TpTe immediately after CRT-D independently predicted VT/VF episodes at 1-year follow-up (hazard ratio [HR], 1.030; P = 0.001).Conclusions:Patients with TpTe shortened at 1-year after CRT had a higher rate of LV reverse remodeling and less VT/VF episodes. The acute changes of TpTe after CRT have minimal value on mechanical reverse remodeling and ventricular arrhythmia.

Novel measure of electrical dyssynchrony predicts response in cardiac resynchronization therapy: Results from the SMART-AV Trial

Cardiac resynchronization therapy (CRT) reduces mortality and morbidity in selected heart failure patients. However, not all patients respond to CRT. We hypothesized that a novel measure of electrical dyssynchrony, sum absolute QRST integral (SAI QRST), predicts CRT response independent of QRS duration and morphology. We retrospectively analyzed baseline 12-lead electrocardiograms of SmartDelay Determined AV Optimization: A comparison to other AV delay methods used in cardiac resynchronization therapy (SMART-AV) trial study participants (N = 234; mean age 67 years; 163 (70%) men; 140 (60%) ischemic cardiomyopathy; mean left ventricular ejection fraction 25%; mean QRS duration 152 ms; 179 (77%) had left bundle branch block). Baseline pre-implant electrocardiograms were digitized, transformed into orthogonal XYZ, and analyzed automatically by customized MATLAB software. SAI QRST was measured as an averaged arithmetic sum of absolute areas under the QRST curve. Patients were followed prospectively 6 months after CRT-defibrillator implantation. Patients with a decrease in left ventricular end-systolic volume ≥15 mL after 6 months of CRT were considered responders. The logistic regression model was adjusted for age, sex, bundle branch block morphology, left ventricular ejection fraction, cardiomyopathy type, and QRS duration. Patients with the high mean SAI QRST (third tertile) had 2.5 times greater odds of response than those with the low mean SAI QRST (first tertile: odds ratio [OR] 2.5; 95% confidence interval [CI] 1.3-5.0; P = .010) and 1.9 times greater than the lower 2 tertiles combined (OR 1.9; 95% CI 1.1-3.5; P = .03). Adjustment for renal function (OR 2.33; 95% CI 1.32-4.11; P = .003) and left ventricular lead position in right anterior oblique and left anterior oblique views (OR 1.7; 95% CI 0.9-3.2; P = .087) did not attenuate association of SAI QRST with outcome. High SAI QRST independently predicts CRT response in the SMART-AV study.

Circulation : Clinical Summaries

<i>Circulation</i> : Clinical Summaries

Super-responders to cardiac resynchronization therapy remain at risk for ventricular arrhythmias and benefit from defibrillator treatment.

Mortality and ventricular arrhythmias are reduced in patients responding to cardiac resynchronization therapy (CRT). This response is accompanied by improvement in LVEF, and some patients even outgrow original eligibility criteria for implantable cardioverter-defibrillator (ICD) implantation. It is however unclear if these patients still benefit from ICD treatment. The current study aimed to evaluate if the incidence of ICD therapy is related to the extent of CRT response. All patients who underwent primary prevention CRT-defibrillator implantation were included. They were divided into subgroups according to the reduction in LV end-systolic volume (LVESV) 6 months after implantation. Pre-defined subgroups were: negative responders (increased LVESV), non-responders (decreased LVESV 0-14%), responders (decreased LVESV 15-29%), and super-responders (decreased LVESV ≥30%). During a median follow-up of 57 months (25th-75th percentile 39-84), 512 patients were studied [101 (20%) negative responders, 101 (20%) non-responders, 149 (29%) responders, and 161 (31%) super-responders]. In the first year of follow-up super-responders received significantly less appropriate ICD therapy (3% vs. 12%; P < 0.001). The 5-year cumulative incidence of appropriate ICD therapy was 31% [95% confidence interval (CI) 19-43] in negative responders, 39% (95% CI 25-53) in non-responders, 34% (95% CI 25-43) in responders, and 27% (95% CI 18-35) in super-responders, respectively (p = 0.13). The extent of CRT response was associated with a parallel reduction of appropriate device therapy during the first year of follow-up. Thereafter, no association was observed. Furthermore, 23% of super-responders were treated for potentially life-threatening arrhythmias and benefit from ICD treatment.

Cardiac Resynchronization Therapy Plus Coupled Pacing Improves Acutely Myocardial Function in Heart Failure Patients

Coupled pacing (CP), which consists of an additional beat delivered after ventricular refractory period, has been proposed to reduce ventricular rate and increase ventricular contractility. We hypothesized that CP may be added to cardiac resynchronization therapy (CRT) to improve CRT effect in heart failure (HF) patients. The study included 20 consecutive HF patients in sinus rhythm referred for CRT-defibrillator (CRT-D) implantation (baseline left ventricular ejection fraction [LVEF] 27 ± 6%, baseline QRS duration 149 ± 33 ms, age = 63 ± 11 years). CP associated with CRT (CRT + CP) was delivered during CRT-D implantation from the right and left ventricular leads simultaneously. Echocardiography data were collected at baseline, during CRT and CRT + CP to assess changes in LVEF, cardiac output (CO), longitudinal global strain assessed by speckle tracking, and LV dyssynchrony (opposing wall delay using tissue Doppler imaging). Compared to the conventional CRT, heart rate (HR) markedly decreased during CRT + CP (79 ± 20 beats/min vs 51 ± 8 beats/min, P < 0.0001) and was associated with a significant increase in LVEF (30 ± 8% vs 35 ± 8%, P = 0.0002) and peak of longitudinal global strain (-6 ± 2% vs -8 ± 2%, P < 0.0001). Importantly, during CRT + CP, CO increased (3.8 ± 1.0 L/min vs 4.4 ± 1.4 L/min, P = 0.004) and cardiac synchronicity remained unchanged (38 ± 24 ms for CRT alone vs 27 ± 18 ms for CRT + CP, P = 0.1). In sinus rhythm HF patients, acute CP application in addition to CRT decreases HR and contributes to myocardial contractility and CO improvement without deleterious impact on ventricular synchronicity.

181: Cardiac resynchronization device implantation procedure in real life. The French Electra survey

Cardiac resynchronization therapy (CRT) has been a major breakthrough in cardiac failure management. However, implantation procedure is not standardized. To evaluate routine implantation procedure habits in french practice. A survey was e-mailed to 100 French CRT implanters in November 2011. Physicians were interviewed on their own strategy in the center. Answers had to concern the most frequent routine attitude. If appropriate, physicians could answer “no standardized attitude or “other”. Among the 62 physicians who answered, 45% practise in a university hospital, 24% in a non-university hospital and 23% in a private institution. The rate of physician implantations is <30/year, 30-50/year and >50/year in 42%, 25% and 33%, respectively. Implantations are performed by a single operator in 49%, and in 43% by two physicians, 16% of implants being done under general anaesthesia. CRT-Pacemaker (CRT-P) implantations are right-sided in 18%, left-sided in 51%, unsettled in 20%, and for CRT-Defibrillator (CRT-D) 8%, 82 and 10% respectively. The venous approach is “all cephalic” in 21%, all subclavian in 18% and combined in 62%. First implanted lead is the right ventricular lead (RV) in 74%, and the coronary sinus (CS) lead in 23%. RV lead is placed in apical position in 26% and in septal position in 67%. To catheterize the CS, a sheath isused in first intention in 81%. CS angiography is performed in 90%, with an inflated balloon in 59%. In case of atrial fibrillation with CHA2DS2-vasc<2, 38% implant without VKA interruption, 57% stop VKA without substitution, and unfractionned heparin (UH) or low weight heparin (LWH) substitution is chosen in 5%, vs respectively 69% and 11% and 19% if CHA2DS2-vasc >4. Most of implantations are performed under local anesthesia. Left sided is prefered, especially in case of CRT-D implantation. Most physicians combine the venous accesses, start with the RV septal lead, and perform a CS angiogram via an inflated balloon. In AF patient, VKA interruption is preferred in low risk patients but not in high risk ones. Few implanters choose VKA substitution.

Intrathoracic Impedance Changes Reflect Reverse Left Ventricular Remodeling in Response to Cardiac Resynchronization Therapy in Chronic Heart Failure Patients

Intrathoracic impedance monitoring has been reported to be useful for prediction of worsening chronic heart failure (CHF). However, it has not revealed the relation between changes in intrathoracic impedance and improvement of cardiac function in CHF patients with cardiac resynchronization therapy (CRT) implantation. Therefore, we investigated whether intrathoracic impedance change reflects reverse left ventricular (LV) remodeling in response to CRT in patients with CHF. The study subjects consisted of 29 CHF patients (23 males, mean age 64 ± 12 years) with CRT-defibrillator (CRT-D) implantation. The patients were divided into two groups based on whether the Opti-vol Fluid Index® reached over 60 ohms (group A, n = 7) or not (group B, n = 22) within 6 months of observation after CRT-D implantation. Levels of plasma B-type natriuretic peptide (BNP) were measured, and LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), and LV ejection fraction (LVEF) were evaluated before and 6 months after CRT-D implantation. In group B, BNP (556 ± 88 pg/mL versus 330 ± 70 pg/mL, P < 0.05), LVEDV (177 ± 18 mL versus 149 ± 14 mL, P < 0.01), and LVESV (128 ± 14 mL versus 100 ± 12 mL, P < 0.01) were significantly decreased 6 months after CRT-D implantation. LVEF (28 ± 2% versus 35 ± 2%, P < 0.01) was significantly increased after CRT-D implantation. On the other hand, no significant changes were detected in any parameters in group A. These data showed intrathoracic impedance changes reflected reverse LV remodeling in response to CRT in patients with CHF. Therefore, the monitoring of changes in intrathoracic impedance is useful for predicting CRT responders in patients with CHF.

Informed Consent in Cardiac Resynchronization Therapy

Cardiac resynchronization therapy (CRT) for the treatment of heart failure (HF) raises complex problems for informed consent. CRT with and without defibrillator backup has been demonstrated in clinical trials to improve symptoms from HF and decrease mortality.1–4 A CRT pacemaker (CRT-P) may improve symptoms and reduce mortality in selected patients, even without offering the specific protection from malignant arrhythmias afforded by a CRT defibrillator (CRT-D). Further, CRT-P may prevent disease progression even in earlier stages of HF.4,5 Implantable cardioverter-defibrillators (ICDs) alone are effective in preventing sudden cardiac death (SCD) in selected patients.6,7 Although most patients eligible for CRT-P will similarly meet guidelines for an ICD, the decision to include ICD backup with a CRT implant may not be straightforward.8 The decision for CRT-P or CRT-D implantation includes not only the medical facts, but also the important considerations based on values and principles. Patients and physicians may wrestle with fundamental questions about quality and quantity of life and struggle to come together toward a truly informed consent process. There are no formal guidelines or standards that argue for specific content to be included in the informed consent process for CRT. This article examines 4 categories of questions regarding CRT based on an understanding of autonomy and shared decision-making as elements of informed consent: (1) control over the manner of death, (2) quality versus quantity of life, (3) therapeutic flexibility, and (4) clinical uncertainty. This article may help to guide clinicians and patients by clarifying the clinical and moral considerations and the principles behind particular treatment decisions. Autonomy refers to an understanding and knowledge of available options and the ability to choose between them through rational deliberation.9,10 Respect for patient autonomy is the foundation of modern bioethics and, in …

Association between Characteristics of Left Ventricular Pacing Lead and Reverse Remodeling in Response to Cardiac Resynchronization Therapy

Backgrounds: It has been shown that the position of left ventricular (LV) pacing lead and viability of the LV wall may affect on the response to cardiac resynchronization therapy (CRT). However, little is known about the association between characteristics of LV pacing lead and LV reverse remodeling in chronic heart failure (CHF) patients with CRT implantation. Methods: The study subjects consisted of 32 CHF patients (23 males, mean age, 64±11 years) with CRT-defibrillator (CRT-D) implantation. We measured LV end-systolic volume (LVESV) by echocardiography before and 6 months after CRT-D implantation and defined the CRT responder as >15% reduction of LVESV at 6 months. The patients were divided into 2 groups based on CRT responder (group-A, n=20) or not (group-B, n=12). We compared the LV R-wave amplitude at CRT-D implantation and the change of LV pacing threshold 6 months after CRT-D implantation between 2 groups. Results: LV R-wave amplitude did not differ between 2 groups (A, 15.1±8.1 mV vs. B, 14.5±8.6 mV). In addition, the change in LV pacing threshold was similar between two groups (improving: 5% vs. 8%; worsening: 25% vs. 25%). Conclusions: These results suggest that electrophysiological properties of regional left ventricle at CRT implantation site do not predict the LV reverse remodeling in response to CRT in CHF patients.

Long-Term Increase of Intrathoracic Impedance after Cardiac Resynchronization Therapy Is Associated with Left Ventricular Reverse Remodeling

Backgrounds: Although acute decrease of intrathoracic impedance measured by cardiac resynchronization therapy (CRT) is effective to detect pulmonary congestion, it is unclear about the association with long-term change of intrathoracic impedance and left ventricular (LV) function in chronic heart failure (CHF) patients with CRT. Methods: Twenty six CHF patients who received CRT-defibrillator (CRT-D) were enrolled. LV dimensions, LV ejection fraction (LVEF) and B-type natriuretic peptide (BNP) were measured before and 6 months after CRT-D implantation. LV reverse remodeling was defined as >15% reduction in LV end-systolic volume after 6 months. In addition, intrathoracic impedance at 1 and 6 months after CRT-D implantation was investigated. The study subjects were divided into 2 groups: 18 patients with increased levels of intrathoracic impedance (Group-A) and 8 patients with decreased (Group-B). We compared LVEF, BNP levels and LV reverse remodeling between two groups. Results: In Group-A, BNP levels decreased and LVEF increased at 6 months after CRT-D implantation (P=0.01, each). In contrast, BNP levels and LVEF did not change in group-B. In Group-A, 15 patients (83%) were classified as LV reverse remodeling despite of 3 patients (37%) in Group-B (P=0.01). Conclusions: These results suggest that long-term increase of intrathoracic impedance is a novel predictor for LV reverse remodeling in CHF patients with CRT.

Scar burden by myocardial perfusion imaging predicts echocardiographic response to cardiac resynchronization therapy in ischemic cardiomyopathy

About 30% of patients with heart failure do not respond to cardiac resynchronization therapy (CRT). We hypothesized that scar burden can predict poor response to CRT in patients with ischemic cardiomyopathy (ICM). Fifty patients (age, 68.5 +/- 9.2 years; 84% men; mean left ventricular ejection fraction (LVEF), 19.7% +/- 5.2%) with ICM who underwent CRT-defibrillator implantation and 201Tl single photon emission computed tomography myocardial perfusion imaging were included. Myocardial perfusion imaging studies were read quantitatively, generating a summed perfusion score (SPS). Left ventricular (LV) lead position was determined by chest radiography. Echocardiograms were performed before and after (median, 11.0 months) CRT. Echocardiographic response, defined as > or = 15% relative increase in LVEF, was documented in 28 (56%) patients. The mean SPS (18.8 +/- 11.3 vs 33.7 +/- 11.1; P = .000025) and the average scar density in the segments immediately adjacent to the LV lead (0.70 +/- 0.91 vs 1.64 +/- 0.82; P = .0004) were significantly lower in responders versus nonresponders. Global scar burden (r = -0.53; P = .00007), scar burden near the LV lead (r = -0.49; P = .0003), and the number of segments with a score of 4 (r = -0.53; P = .0007) inversely correlated with increase in LVEF after CRT. The hazard ratio for nonresponse increased with increasing tertiles of global SPS, scar density in the vicinity of the LV lead, and number of segments with transmural scar (ie, perfusion score = 4). Higher overall scar burden, a larger number of severely scarred segments, and greater scar density near the LV lead tip portend an unfavorable response to CRT in ICM patients. Prospective confirmation of these findings is warranted.