MSA-VT Score for Assessment of Long-Term Prognosis after Electrical Storm Ablation.

INTRODUCTION: Prognosis after electrical storm (ES) ablation remains severe, especially in patients with recurrent sustained monomorphic ventricular tachycardia (SMVT) or progressive heart failure (HF). However, single-factor-based prediction is suboptimal and may be refined by more complex algorithms. We sought to evaluate if a novel score MSA-VT (M = moderate/severe mitral regurgitation, S = severe HF at admission, A = atrial fibrillation at admission, VT = inducible SMVT after ablation) may improve prediction of death and recurrences compared to single factors and previous scores (PAINESD, RIVA and I-VT). METHODS: A total of 101 consecutive ES ablation patients were retrospectively analyzed over a 32.8-month (IQR 10-68) interval. The MSA-VT score was calculated as the sum of the previously mentioned factors' coefficients based on hazard ratio values in Cox regression analysis. The AUC for death prediction by MSA-VT was 0.84 (p < 0.001), superior to PAINESD (AUC 0.63, p = 0.03), RIVA (AUC 0.69, p = 0.02) and I-VT (0.56, p = 0.3). MSA-VT ≥ 3 was associated with significantly higher mortality during follow-up (52.7%, p < 0.001). CONCLUSIONS: Prediction by single factors and previously published scores after ES ablation may be improved by the novel MSA-VT score; however, this requires further external validation in larger samples.

Long QT Syndrome and WPW Syndrome: A Very Rare Association between Two Causes of Sudden Cardiac Death in a Young Patient.

Long QT syndrome (LQT) and WPW syndrome are causes of sudden cardiac death (SCD) in the young, and their association has been rarely reported. A 26-year-old woman presented with recurrent syncope. Her ECG showed a short PR interval, wide QRS (150 ms) due to a delta wave, and QT prolongation (QT 580 ms, QTc 648 ms). ECG monitoring documented recurrent salvos of a self-terminating wide QRS tachycardia, generally slightly polymorphic, sometimes with "torsade des pointes" (TdP) appearance, which were linked to the syncopal/presyncope episodes. Electrophysiologic monitoring diagnosed a right para-hisian accessory pathway with a very short ERP (240 ms baseline, <200 ms after isoproterenol). The pathway was ablated successfully. Despite QRS narrowing (80 ms), QT prolongation persisted after ablation (QT 620 ms, QTc 654 ms), with short runs of TdP, despite beta-blocker treatment, which was increased to the maximal dosage. A dual-chamber implantable cardioverter defibrillator (ICD) was implanted. To our knowledge, this is the first case report of an association between LQT and WPW syndrome in which both conditions are associated with an increased risk of SCD.

The Association between Diagnosis-to-Ablation Time and the Recurrence of Atrial Fibrillation: A Retrospective Cohort Study.

BACKGROUND: Catheter ablation (CA) for atrial fibrillation (AF) is superior to antiarrhythmic drugs in maintaining sinus rhythm. Novel evidence suggests that increasing the time between the first diagnosis of AF and ablation, or diagnosis-to-ablation time (DAT), is a predictor for AF recurrence post-ablation. PURPOSE: Our primary objective was to investigate the relationship between DAT and AF recurrence after a first ablation. METHODS: Patients with AF who underwent CA in our center were enrolled consecutively, and a retrospective analysis was performed. DAT was treated as a continuous variable and reported as a median for the group with recurrence and the group without recurrence. DAT was also considered as a categorical variable and patients were stratified into three categories: DAT < 1 year, DAT < 2 years, and DAT < 4 years. RESULTS: The cohort included 107 patients, with a mean age of 54.3 ± 11.7 years. Mean DAT was significantly longer in those with AF recurrence: 4.9(3.06) years versus 3.99(3.5) (p = 0.04). The Kaplan-Meier curve revealed a higher likelihood of AF-free status over time for patients with DAT < 2 years compared to those with DAT > 2 years (p = 0.04). Cox multivariate analysis indicated that left atrial volume index (LAVI), obstructive sleep apnoea (OSA), and DAT > 2 years were independently associated with AF recurrence after a single AF ablation procedure (p = 0.007, p = 0.02, and p = 0.03, respectively). CONCLUSION: A shorter duration between the first AF diagnosis and AF ablation is associated with an increased likelihood of procedural success after a single AF ablation procedure.

Feasibility of Conduction System Pacing in Patients with Baseline Bundle Branch Block-A Single-Center Mid-Term Follow-Up Study.

BACKGROUND: The primary prerequisite for a successful conduction system pacing (CSP) procedure is the integrity of the conduction system, which may be impaired if a baseline bundle branch block (BBB) is present. This study aimed to evaluate the feasibility and mid-term performance of permanent CSP in patients with baseline BBB and to compare the results between left bundle branch block (LBBB) and right bundle branch block (RBBB) patterns. MATERIAL AND METHODS: A total of 101 patients with typical BBB and an attempt at CSP were retrospectively reviewed. Procedural characteristics, pacing, sensing parameters, and complications at baseline and after a mid-term follow-up were analyzed. RESULTS: The global procedural success for CSP was 93%. His bundle pacing (HBP) had a significantly lower success rate than left bundle branch area pacing (LBBAP) (50.5% vs. 86%). The paced QRS duration was significantly narrower with HBP. The pacing and sensing thresholds were significantly better with LBBAP. Procedural complications occurred only in the LBBAP group (two acute perforations in the LV cavity and one acute chest pain during lead fixation) without long-term sequelae. The HBP and the LBBAP procedural success rates were higher in the RBBB versus the LBBB group (62.5% vs. 44.9% and 100% vs. 81.5%, respectively). Baseline QRS duration, atrial volumes, and right ventricular diameters were significantly associated with HBP procedural failure. The follow-up pacing and sensing thresholds were similar to the baseline values for all pacing methods and BBB morphology. Only one device-related complication leading to pacing interruption was recorded. CONCLUSION: In patients with bundle branch blocks, CSP is a feasible procedure associated with a high success rate, stable pacing and sensing parameters, and low complication rates over a mid-term follow-up.

Predictors for Super-Responders in Cardiac Resynchronization Therapy.

BACKGROUND: Prediction of cardiac resynchronization therapy (CRT) response, particularly a super-response, is of great importance. STUDY QUESTION: The aim of our study was to assess the predictors for super-responders in CRT. STUDY DESIGN: We conducted a retrospective, observational study, which finally included 622 patients with heart failure treated with CRT between January 2008 and May 2020 who had a minimal follow-up of 6 months after CRT. MEASURES AND OUTCOMES: A total of 192 super-responders, defined by a left ventricular ejection fraction (LVEF) of at least 45%, and/or minimum 15% increase in LVEF and an improvement of the New York Heart Association functional class by at least 2 degrees at the last follow-up, and the rest of 430 patients who did not fulfill the super-responder criteria. RESULTS: The highest rate of super-responders (41.91%, n = 171) was at patients with left ventricle-only pacing with optimal fusion (OPT) compared with patients with biventricular (BiV) pacing (9.81%, n = 21, P < 0.000). In the OPT group, univariable analysis showed that nonischemic cardiomyopathy, a smaller degree of mitral regurgitation, and better left ventricle function at enrollment were predictors for super-response compared with the BiV group where a narrower QRS after implantation, nonischemic cardiomyopathy, and a better baseline LVEF were predictors for super-responders. In the multivariable analysis, both narrower QRS after implantation and nonischemic cardiomyopathy were independent predictors for super-response in the BiV group compared with OPT where nonischemic cardiomyopathy remained the only independent predictor for super-response. CONCLUSIONS: In this retrospective study, OPT CRT programing was an additional predictor of super-response to CRT besides nonischemic cardiomyopathy.

Left Atrial Low-Voltage Areas Predict the Risk of Atrial Fibrillation Recurrence after Radiofrequency Ablation.

Atrial fibrillation (AF), the most frequently encountered arrhythmia worldwide, is associated with increased cardiovascular morbidity and mortality. Left atrial (LA) and antral region of the pulmonary veins (PVs) remodeling are risk factors for AF perpetuation. Among the methods of LA fibrosis quantification, bipolar voltage mapping during three-dimensional electro-anatomical mapping is less studied. The main aim of this study was to analyze the relationship between the degree of LA fibrosis quantified in low-voltage areas and the efficacy of AF radiofrequency catheter ablation. All consecutive patients with AF ablation were included, and the degree of LA fibrosis was measured based on the low-voltage areas in the LA and the antral region of PVs (<0.5 mV for patients in sinus rhythm and <0.25 mV for patients in AF at the time of the ablation procedure). The efficacy of AF ablation was determined by the rate of recurrence after a blanking period of three months. A total of 106 patients were included; from these, 38 (35.8%) had AF recurrence after RF ablation, while 68 (64.2%) were free of events. The area and percentage of LA fibrosis were significantly higher in the patients with AF recurrence (p = 0.018 and p = 0.019, respectively). However, no significant differences were found between the patients with and without AF recurrence in terms of the area and percentage of PVs fibrosis (p = 0.896 and p = 0.888, respectively). Moreover, LA fibrosis parameters proved to be excellent predictors for AF recurrence (areas under the curve of 0.834 and 0.832, respectively, p < 0.001) even after adjustment for LA indexed volume and CHA2DS2-VASc score. In conclusion, LA fibrosis measured on bipolar voltage maps increases the risk of AF recurrence after the RF catheter ablation procedure.

Transvenous Lead Extraction of Cardiac Implantable Electronic Devices: Reimplant Strategy and Outcomes in a Single-Center Experience.

Cardiac implantable electronic devices are now widely used worldwide and the numbers are increasing exponentially. Subsequently, long-term complications have increased. Transvenous lead-extraction (TLE) is the gold standard for removing infected devices, treating systemic device-related infections including endocarditis, and removing devices for other non-infectious complications. Most patients still require device therapy after TLE for several indications, including lifesaving defibrillation or pacing in pacemaker-dependent patients. The decision to reimplant is challenging, particularly when the primary cause for device removal includes device-related infections and patients frequently are pacemaker dependent. We aim to present our strategy for reimplanting after performing TLE in 88 consecutive patients. We performed transvenous removal of 150 pacemaker and defibrillator leads, of which 74% for local or systemic infection. We report a 99.3% clinical success after TLE. Out of 88 patients who had undergone TLE and after reanalysing the device indication, 67 patients (76%) still had indication for device removal, but three of them refused to undergo reimplant and 58 were re-implanted. Of the re-implanted patients, 58.6% were implanted on the contra-lateral side, 38% on the ipsilateral side and two patients who had been previously implanted with ICD were reimplanted with a subcutaneous implantable cardioverter defibrillator (S-ICD). Up to 34.4% of patients were re-implanted during the same TLE procedure, which was performed for device up-grade in patients with venous occlusion, 24% were implanted during the same hospital admission for TLE but not during TLE, and 41.3% were discharged and reimplanted afterwards. With this strategy for reimplantation, we report no re-infections and no device-removal-related arrhythmic major events or deaths during one-year follow-up. In conclusion, most patients still require device therapy after TLE. In patients with previous infection of the device, the reimplantation strategy should be carefully analyzed to prevent infection relapse and limit the consequences of the absence of the device.

Non-revascularized chronic total occlusions impact on substrate and post-ablation results in drug-refractory electrical storm.

Background and aims: There is limited data concerning the effect of non-revascularized chronic total occlusions (NR-CTOs) after VT ablation. This study sought to evaluate the impact of NR-CTOs after ablation for electrical storm (ES). Methods: Post-hoc retrospective analysis of data regarding 64 consecutive post-myocardial infarction patients (out of which 12 patients with NR-CTOs and 52 without NR-CTOs) undergoing substrate ablation for ES with an available median follow-up of 37.53 (7.25-64.65) months. Ablation result was assessed by inducibility of sustained monomorphic VT (SMVT) during final programmed ventricular stimulation (PVS). The primary endpoints were all-cause mortality and VT/VF recurrences after ablation, respectively, stratified by the presence of NR-CTOs. The secondary endpoint was to assess the predictive effect of NR-CTOs on all-cause mortality and VT/VF recurrences in relation to other relevant prognostic factors. Results: At baseline, the presence of NR-CTOs was associated with higher bipolar BZ-to-total scar ratio (72.4% ± 17.9% vs. 52% ± 37.7%, p = 0.022) and more failure to eliminate the clinical VT (25% (3) vs. 0% (0), p < 0.001). During follow-up, overall all-cause mortality and recurrences were more frequent in the NR-CTO subgroup (75% (9) vs. 19.2% (10), log rank p = 0.003 and 58.3% vs. 23.1% (12), log rank p = 0.042 respectively). After adjusting for end-procedural residual SMVT inducibility, NR-CTOs predicted death during follow-up (HR 3.380, p = 0.009) however not recurrence (HR 1.986, p = 0.154). Conclusions: NR-CTO patients treated by RFCA for drug-refractory ES demonstrated a higher ratio of BZ-to-total-scar area. In this analysis, NR-CTO was associated with worse acute procedural results and may as well impact long-term outcomes which should be further assessed in larger patient populations.

New Score for Predicting Results after Catheter Ablation for Atrial Fibrillation: VAT-DHF.

INTRODUCTION: Catheter ablation (CA) for atrial fibrillation (AF) has been proven to have the highest efficacy in maintaining sinus rhythm. Several studies have proposed different scores for predicting post-procedural success, but most have not been validated in prospective cohorts. Further research is required to determine the optimal formulae. PURPOSE: This study aimed to identify independent predictors of AF recurrence after CA and develop a composite score. METHODS: Consecutive patients with persistent and paroxysmal AF who underwent CA were retrospectively analyzed. The independent predictors of recurrence were used to create a new predictive score. RESULTS: The cohort included 263 patients with a follow-up of 37.6 ± 23.4 months. Persistent AF, f-waves < 0.1 mV, indexed left atrium volume, the presence of type 2 diabetes, and smaller height were independent predictors of recurrence and were used to create a new scoring model, VAT-DHF (V = Volume, AT = AF Type, D = Diabetes, H = Height, F = f waves). The ROC curve for this new score showed an AUC of 0.869, p < 0.0001, 95% CI [0.802-0.936], while those for APPLE and CHA2DS2-VASc showed an AUC of 0.765, 95% CI [0.637-0.893] and an AUC of 0.655, 95% CI [0.580-0.730], respectively. Patients who had a VAT-DHF score between 0 and 3.25, 3.25 and 6, and ≥6, had success rates of 95.7%, 76.3%, and 25% (p < 0.0001), respectively. CONCLUSIONS: The novel VAT-DHF score is easy to calculate and may be a useful clinical tool for identifying patients with a low, intermediate, or high risk of AF recurrence after CA.

Monomorphic VT Non-Inducibility after Electrical Storm Ablation Reduces Mortality and Recurrences.

Background: Electrical storm (ES) is defined by clustering episodes of ventricular tachycardia (VT) and is associated with severe long-term outcomes. We sought to evaluate the prognostic impact of radiofrequency catheter ablation (RFCA) in ES as assessed by aggressive programmed ventricular stimulation (PVS). Methods: Single-center retrospective longitudinal study with 82 consecutive ES patients referred for RFCA with a median follow-up (IQR 25−75%) of 45.43 months (15−69.86). All-cause mortality and VT recurrences were assessed in relation to RFCA outcomes defined by 4-extrastimuli PVS: Class 1­no ventricular arrhythmia; Class 2­no sustained monomorphic VTs (mVT) inducible, but non-sustained mVTs, polymorphic VTs, or VF inducible; Class 3­clinical VT non-inducible, other sustained mVTs inducible; and Class 4­clinical VT inducible. Results: Class 1, Class 2, Class 3, and Class 4 were achieved in 56.1%, 13.4%, 23.2%, and 7.4% of cases, respectively. The combined outcome of Class 1 + Class 2 (no sustained monomorphic VT inducible) led to improved survival (log-rank p < 0.001) and reduced VT recurrence (log-rank p < 0.001). Residual monomorphic VT inducibility (HR 6.262 (95% CI: 2.165−18.108, p = 0.001), NYHA IV heart failure symptoms (HR 20.519 (95% CI: 1.623−259.345), p = 0.02)), and age (HR 1.009 (95% CI: 1.041−1.160), p = 0.001)) independently predicted death during follow-up. LVEF was not predictive of death (HR 1.003 (95% CI: 0.946−1.063) or recurrences (HR 0.988 (95% CI: 0.955−1.021)). Conclusions: Non-inducibility for sustained mVTs after aggressive PVS post-RFCA leads to improved survival in ES, independently of LVEF.

Case Report: Pulmonary Vein Isolation as a Tailored Treatment for Recurrent Ventricular Tachycardia During Hemodialysis in a Patient With Right Coronary Artery Chronic Total Occlusion.

Background: Catheter ablation of the ventricular substrate can reduce ventricular tachycardia (VT) recurrence and mortality in an electrical storm (ES). However, identification and specific treatment of plausible triggers is mandatory and may lead to the resolution of ES. Objective: This case presentation seeks to exemplify how pulmonary vein isolation (PVI) may represent a tailored treatment of ES in cases of ventricular substrate, which only becomes arrhythmogenic during high-rate episodes of paroxysmal atrial fibrillation (PAF). Results: A 54-year-old male with a history of inferior myocardial infarction (MI) and long-term hemodialysis was referred for repetitive implantable cardioverter-defibrillator (ICD) shocks for apparently scar-related monomorphic VT episodes preceded by PAF initiation strictly during hemodialysis. He had recently undergone ICD implantation for similar episodes of ES preceded by the rapid-ventricular response (RVR) PAF during hemodialysis. The patient had no other history of VTs. Electrocardiogram (EKG) changes occurred exclusively during PAF and suggested functional myocardial ischemia. Coronary angiography demonstrated isolated right coronary artery (RCA) chronic total occlusion (CTO). Cardiac magnetic resonance demonstrated RCA-territory residual myocardial viability and mild LV systolic dysfunction. Surgical revascularization was not feasible due to a history of bilateral above-the-knee post-traumatic amputation and severe calcification of internal mammary (IMA) and radial arteries. Subsequent CTO-percutaneous coronary intervention attempt was unsuccessful. The difficulty of assessing LV-substrate ablation end-points due to the "functional" character of the substrate, which only became arrhythmogenic during hemodialysis-related PAF, was considered. Consequently, PVI was performed rather than VT/VF substrate ablation. Twelve months after PVI, the patient remains free of PAF and VT/VF despite chronic hemodialysis sessions. Conclusion: The ES episodes can be triggered by situational factors, such as RVR-PAF and functional ischemia, during hemodialysis in patients with CTO with otherwise no episodes of VT. Tailored treatment of such factors may lead to long-term VT freedom.

Ratio between Right Ventricular Longitudinal Strain and Pulmonary Arterial Systolic Pressure: Novel Prognostic Parameter in Patients Undergoing Cardiac Resynchronization Therapy.

BACKGROUND: We aimed to evaluate whether right ventricle (RV) longitudinal strain indexed to pulmonary arterial systolic pressure (PASP) has prognostic significance in patients undergoing cardiac resynchronization therapy (CRT). METHODS: Patients undergoing CRT were prospectively included. The primary endpoint was adverse cardiovascular events (death and HF-related hospitalizations). RV global longitudinal strain (RVGLS) and RV free wall strain (RVfwS) were measured by speckle tracking and indexed to echocardiographic estimated PASP. RESULTS: A total of 54 patients (64.0 ± 13.8 years; 58% male) were included. After 33 ± 12.9 months, the primary endpoint occurred in 18 patients. Baseline RVGLS/PASP and RVfwS/PASP showed good discriminative ability for response to CRT (AUC = 0.88, 95% CI (0.74-1) and AUC = 0.87, 95% CI (0.77-1)). RVGLS/PASP and RVfwS/PASP were significantly associated with high risk of events at univariate analysis (HR 0.039, 95% CI (0.001-0.8) p < 0.05, respectively HR = 0.049, 95% CI (0.0033-0.72), p < 0.05). Upon multivariate Cox regression analysis, RVGLS/PASP and RVfwS/PASP remained associated with high risk of events (HR 0.018, 95% CI (0.0005-0.64), p = 0.02 and HR 0.015, 95% CI (0.0004-0.524), p = 0.01) after correction for gender, etiology, QRS duration and morphology. Conclusions: Indexing RV longitudinal strain (global and free wall) by PASP provides a parameter, which independently identifies patients with high risk of cardiovascular events and predicts non-response to CRT.

Right ventricular-arterial coupling - A new perspective for right ventricle evaluation in heart failure patients undergoing cardiac resynchronization therapy.

BACKGROUND: Right ventricular - arterial (RV-PA) coupling can be estimated by echocardiography using the ratio between (TAPSE) and pulmonary arterial systolic pressure (PASP). TAPSE/PASP ratio proved to be a prognostic parameter in patients with heart failure and reduced ejection fraction (HFrEF). OBJECTIVE: To evaluate the significance of RV-PA coupling in patients with HFrEF undergoing cardiac resynchronization therapy (CRT). METHODS: Patients undergoing CRT in our center between January 2017 and November 2019 were eligible. Response to CRT was defined by a reduction of more than 15% of left ventricle systolic volume (LVESV) one year after CRT. Primary endpoint was a composite of HF hospitalizations and death during follow-up. RESULTS: 54 patients (Age 64.0 ± 13.8 years; 58% male; left ventricular ejection fraction (LVEF) 28.4 ± 1.3%) were prospectively included. After a mean follow-up of 31 ± 12.9months, the primary endpoint had occurred in 18 (33.3%) patients. A lower TAPSE/PASP ratio was associated with baseline worse HF symptoms, lower LVEF and long-term less LV reverse remodeling (P < .05). After one year CRT improved RV systolic function (TAPSE, RV global longitudinal strain, P < .05), but not TAPSE/PASP ratio (P = .4). The ratio TAPSE/PASP (AUC=0.834) ≥ 0.58 mm/mm Hg showed good sensitivity (90%) and specificity (81.8%) for predicting response to CRT while a ratio <0.58 mm/mm Hg was associated with a higher risk of death and HF hospitalizations during the follow-up (HR 5.37 95%CI [1.6-18], P < .001). CONCLUSION: RV-PA coupling evaluation using TAPSE/PASP ratio predicts CRT response. A lower TAPSE/PASP ratio is associated with a higher risk of adverse cardiovascular events.

Yield of Rare Variants Detected by Targeted Next-Generation Sequencing in a Cohort of Romanian Index Patients with Hypertrophic Cardiomyopathy.

BACKGROUND: The aim of this study was to explore the rare variants in a cohort of Romanian index cases with hypertrophic cardiomyopathy (HCM). METHODS: Forty-five unrelated probands with HCM were screened by targeted next generation sequencing (NGS) of 47 core and emerging genes connected with HCM. RESULTS: We identified 95 variants with allele frequency < 0.1% in population databases. MYBPC3 and TTN had the largest number of rare variants (17 variants each). A definite genetic etiology was found in 6 probands (13.3%), while inconclusive results due to either known or novel variants were established in 31 cases (68.9%). All disease-causing variants were detected in sarcomeric genes (MYBPC3 and MYH7 with two cases each, and one case in TNNI3 and TPM1 respectively). Multiple variants were detected in 27 subjects (60%), but no proband carried more than one causal variant. Of note, almost half of the rare variants were novel. CONCLUSIONS: Herein we reported for the first time the rare variants identified in core and putative genes associated with HCM in a cohort of Romanian unrelated adult patients. The clinical significance of most detected variants is yet to be established, additional studies based on segregation analysis being required for definite classification.

Cardiac resynchronization therapy in patients with chronic heart failure is associated with anti-inflammatory and anti-remodeling effects.

OBJECTIVES: Proinflammatory cytokines, matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) play a role in left ventricular (LV) structural remodeling. We aimed to investigate the effects of cardiac resynchronization therapy (CRT) on serum levels of amino-terminal prohormone B-type natriuretic peptide (NT-proBNP), some interleukins (IL-1ß, IL-6, IL-8), MMP-2 and TIMP-2 in patients with chronic heart failure (CHF). DESIGN AND METHODS: We studied 27 patients (15 M/12 F) with CHF, III-IV NYHA class, implanted with a biventricular pacemaker/defibrillator and 40 healthy subjects (23 M/17 F). Blood samples were collected at baseline and 1 week, 3, 6, and 12 months after CRT device implantation. Cardiac function was assessed echocardiographically. RESULTS: CRT induced significant improvement in the NYHA class (baseline 3.2±0.5 vs. 1.0 at 12 months, P=0.0002) and significant LV reverse remodeling, with a 41% (P=0.001) reduction in LV end-systolic volume (LVESV). This was associated with a significant reduction in serum NT-proBNP, IL-6 and IL-8. Positive extracellular matrix remodeling was illustrated by decreasing levels of MMP-2 and increasing TIMP-2. MMP-2/TIMP-2 ratio decreased with 55% (P=0.003) from baseline value at 12 months and the correlation with LVESV reduction was 0.41 (P=0.001). CONCLUSIONS: Structural response to CRT is associated with reduced immune activation and positive extracellular matrix remodeling.