Left bundle branch block-induced cardiomyopathy: a diagnostic proposal for a poorly explored pathological entity

Relationship between myocardial fibrosis and left bundle branch block. Does it exist?

AIM

to assess the relation of focal and diffuse left ventricular (LV) fibrosis to left bundle branch block (LBBB).

MATERIALS AND METHODS

60 patients with dilated cardiomyopathy and LBBB (DCM-LBBB), 50 DCM-nonLBBB patients, 15 patients with LBBB and structurally normal heart (idiopathic LBBB) and 10 healthy volunteers (HV) underwent cardiovascular magnetic resonance (CMR) with late gadolinium enhancement (LGE). LGE LV images were post-proceeded for core scar (CS) and gray zone (GZ) calculation. Diffuse LV fibrosis was estimated on LGE-CMR images with the diffuse intensity ratio (DIR). Endomyocardial biopsy (EMB) was performed in 15(24.6 %) DCM-LBBB and 16 (32 %) non-LBBB DCM patients and allowed the quantification of collagen volume fraction (CVF).

RESULTS

The percentage of CVF correlated with the DIR value in the same segment (r = 0.66, p < 0.001). The value of CVF in EMB and frequency of LGE in both DCM groups was comparable (p = 0.8). In DCM-nonLBBB patients the percentage of CS was significantly higher (4.0[1.6; 11.7]% versus 1.4[0.1;8.5]% in DCM-LBBB patients, p = 0.047), whereas percentage of GZ and total fibrosis in both DCM groups was comparable. DIR value was higher in patients with idiopathic LBBB than in HV (0.54±0.09 versus 0.34±0.1, р<0,001).

CONCLUSION

Neither focal nor interstitial fibrosis is associated with LBBB in DCM patients. Diffuse inflammation in DCM-LBBB patients may contribute to the progression of systolic dysfunction but is not a cause of LBBB. The increased value of interstitial fibrosis in patients with idiopathic LBBB may reflect latent diffuse process in myocardium inexorably leading to DCM development.

Left bundle branch block cardiomyopathy (LBBB-CMP): from the not-so-benign finding of idiopathic LBBB to LBBB-CMP diagnosis and treatment

Introduction Idiopathic left bundle branch block (iLBBB) is an uncommon finding. Its benignity has been increasingly questioned, though its natural history remains poorly clarified. Similarly, LBBB-cardiomyopathy (LBBB-CM) has been also increasingly recognized as a distinct entity, where electromechanical dyssynchrony seems to play a central role in left ventricular dysfunction (LVD) development. Still, it remains a scarcely studied topic. There is an urgent need for investigation and evidence reinforcement in these areas.

OBJECTIVES

two main objectives: (1) to explore the natural history of "asymptomatic" iLBBB carriers; (2) to characterize the outcomes and therapeutic approach used in a "real-world" cohort of possible LBBB-CMP patients (pts).

METHODS

tertiary care centre retrospective study of pts with iLBBB and possible LBBB-CMP, screened from a large hospital electrocardiographic database from 2011 to 2017 (LBBB = 347). To assign the 1st objective, only pts with left ventricular ejection fraction (LVEF) ≥ 50% and available follow-up (FU) data were included (n = 152). Regarding the 2nd objective, possible LBBB-CMP pts were selected and defined as iLBBB pts with LVD (LVEF < 50%) and no secondary causes for LVD (n = 53). Data were based on pts' careful review of medical records.

RESULTS

focusing our 1st objective, 152 iLBBB carriers were identified. Median FU time were 8 years, and 61% were female. During FU, approximately 25% developed LVD, 20% needed ≥ 1 cardiovascular (CV) hospitalization, and 15% needed a cardiac device implantation. The majority (2/3) of pts with LVD on FU (n = 35) had no secondary causes for LVD, being classified as possible LBBB-CMP pts. Time-to-LVD analysis showed no differences between pts with a known cause for LVD vs LBBB-CMP pts (Log-rank = 0.713). Concerning the 2nd objective, 53 possible LBBB-CMP pts were identified. Median FU time were 10 years, and 51% were female. During the FU, 77% presented heart failure (HF) symptoms, and 42% needed ≥ 1 CV hospitalization, mainly due to HF. Half presented severe LVD at some point in time, and 55% needed a cardiac device, most of them a cardiac resynchronization therapy (CRT) device. Comparing CRT with non-CRT pts, no differences were found in terms of medical therapy, but better outcomes were observed in CRT group: LVEF improvement was higher (median LVEF improvement of 11% in non-CRT vs 27% in CRT; p < 0.001), and fully recovery from LVD was more frequent (50% of CRT vs 14% non-CRT; p = 0.028).

CONCLUSION

our data strengthen current evidence on natural history of iLBBB, showing significant CV morbidity associated with the presence of iLBBB, and reinforces the need for a serial and proper FU of these carriers. Our data on "real-world" possible LBBB-CMP pts shows high rates of CV events, namely HF-related events, and supports the growing evidence pointing out CRT as this subgroup of pts' cornerstone of treatment. In conclusion, our work sheds additional light on these largely unknown topics and underlines the urgent need for larger and prospective studies addressing the identification of LVD development predictors in iLBBB carriers, as well as the establishment of diagnostic criteria and therapeutic approach for LBBB-CMP.

Left bundle branch block-Innocent bystander, silent menace, or both

Left bundle branch block (LBBB) causes immediate electrical and mechanical dyssynchrony of the left ventricle (LV) and gradual structural damages in the Purkinje cells and myocardium. Mechanical dyssynchrony reduces the LV ejection fraction (EF) instantly, but only to ≈55% in an otherwise normal heart. Because of the heart's in-built functional redundancy, a patient with LBBB does not always notice the heart's reduced efficiency straightaway. After a variable period of time (which could be from days to decades), the patient may become symptomatic with heart failure (HF), which classifies as HF with preserved EF ≥50% (HFpEF). The LVEF drops further because of continuous adverse remodeling and inefficient cardiac contraction. The patient transits to HF with moderately reduced EF 35%-50% (HFmrEF) and then reduced EF ≤35% (HFrEF) over 5-21 years. Cardiac resynchronization therapy (CRT) is currently only indicated in guidelines for HFrEF and LBBB. LBBB shortens the median survival of patients with HFmrEF by 5.5 years. Randomized controlled trials have shown that CRT improves echocardiographic indices for HFmrEF with LBBB. CRT in HFpEF with LBBB is a promising but underexplored/underused therapy. There have been anecdotal reports that CRT produced symptom relief in patients debilitated by HFpEF with LBBB, who constitute ≈6% of all patients with HF and an adequate pool of potential randomized controlled trial participants. Conduction system pacing in the form of left bundle branch area pacing is an emerging pacing strategy that might reverse and forestall the deleterious effects of LBBB.

Left bundle branch block-induced dilated cardiomyopathy: Definitions, pathophysiology, and therapy

Left bundle branch block (LBBB) is a frequent finding in patients with heart failure (HF), particularly in those with dilated cardiomyopathy (DCM). LBBB has been commonly described as a consequence of DCM development. However, a total recovery of left ventricular (LV) function after cardiac resynchronization therapy (CRT), observed in patients with LBBB and DCM, has led to increasing acknowledgement of LBBB-induced dilated cardiomyopathy (LBBB-iDCM) as a specific pathological entity. Its recognition has important clinical implications, as LBBB-iDCM patients may benefit from an early CRT strategy rather than medical HF therapy only. At present, there are no definitive diagnostic criteria enabling the universal identification of LBBB-iDCM, and no defined therapeutic approach in this subgroup of patients. This review compiles the main findings about LBBB-iDCM pathophysiology and the current proposed diagnostic criteria and therapeutic approach.

Withdrawal of drug therapy in responders to cardiac resynchronization therapy: rationale and design of the REMOVE trial

INTRODUCTION AND OBJECTIVES

Cardiac resynchronization therapy (CRT) is an effective treatment for patients with nonischemic dilated cardiomyopathy associated with left bundle branch block (LBBB). In these patients, the device can normalize left ventricular ejection fraction (LVEF). Nevertheless, it remains unclear whether CRT responders still require neurohormonal blockers. The aim of this study is to determine the long-term safety of withdrawing drug therapy in these patients.

METHODS

The REMOVE trial is a prospective, multicenter, open-label and randomized 1:1 study designed to assess the effect of withdrawing neurohormonal blockers in patients with nonischemic dilated cardiomyopathy associated with left bundle branch block who recovered LVEF after CRT. The study will include a 12-month follow-up with the option to continue into the follow-up extension phase for up to 24 months. The primary endpoint is the recurrence of cardiomyopathy defined as any of the following criteria: a) a reduction in LVEF >10% (provided the LVEF is <50%); b) a reduction in LVEF >10% accompanied by an increase >15% in the indexed end-systolic volume relative to the previous value and in a range higher than the normal values, or c) decompensated heart failure requiring intravenous diuretic administration. In patients meeting the primary endpoint, drug therapy will be restarted.

CONCLUSIONS

The results of this study will help to enhance our understanding of CRT superresponders, a specific group of patients. Registred at ClinicalTrials.gov (Identifier: NCT05151861).

Impact of DCM-Causing Genetic Background on Long-Term Response to Cardiac Resynchronization Therapy

BACKGROUND

Patients with nonischemic dilated cardiomyopathy (DCM), severe left ventricular (LV) dysfunction, and complete left bundle branch block benefit from cardiac resynchronization therapy (CRT). However, a large heterogeneity of response to CRT is described. Several predictors of response to CRT have been identified, but the role of the underlying genetic background is still poorly explored.

OBJECTIVES

In the present study, the authors sought to define differences in LV remodeling and outcome prediction after CRT when stratifying patients according to the presence or absence of DCM-causing genetic background.

METHODS

From our center, 74 patients with DCM subjected to CRT and available genetic testing were retrospectively enrolled. Carriers of causative monogenic variants in validated DCM-causing genes, and/or with documented family history of DCM, were classified as affected by genetically determined disease (GEN+DCM) (n = 25). Alternatively, by idiopathic dilated cardiomyopathy (idDCM) (n = 49). The primary outcome was long-term LV remodeling and prevalence of super response to CRT (evaluated at 24-48 months after CRT); the secondary outcome was heart failure-related death/heart transplant/LV assist device.

RESULTS

GEN+DCM and idDCM patients were homogeneous at baseline with the exception of QRS duration, longer in idDCM. The median follow-up was 55 months. Long-term LV reverse remodeling and the prevalence of super response were significantly higher in the idDCM group (27% in idDCM vs 5% in GEN+DCM; P = 0.025). The heart failure-related death/heart transplant/LV assist device outcome occurred more frequently in patients with GEN+DCM (53% vs 24% in idDCM; P = 0.028).

CONCLUSIONS

Genotyping contributes to the risk stratification of patients with DCM undergoing CRT implantation in terms of LV remodeling and outcomes.

Abnormal conduction-induced cardiomyopathy: a poorly explored entity

A dyssynchronous biventricular activation, which can be determined by left bundle branch block, chronic right ventricular pacing, frequent premature ventricular complexes, or pre-excitation, can cause a global abnormal contractility, thus leading to systolic dysfunction and left ventricular remodelling in a unique nosological entities: abnormal conduction-induced cardiomyopathies. In this clinical scenario, the mainstay therapy is eliminating or improving LV dyssynchrony, removing the trigger. This usually ensures the improvement and even recovery of cardiac geometry and left ventricular function, especially in the absence of genetic background. A multidisciplinary approach, integrating advanced multimodal imaging, is essential for the systematic aetiological definition and the subsequent evaluation and aetiology-guided therapies of patients and their families. This review aims to describe mechanisms, prevalence, risk factors, and diagnostic and therapeutic approach to the various abnormal conduction-induced cardiomyopathies, starting from reasonable certainties and then analysing the grey areas requiring further studies.

Nonischemic or Dual Cardiomyopathy in Patients With Coronary Artery Disease

BACKGROUND

Randomized trials in obstructive coronary artery disease (CAD) have largely shown no prognostic benefit from coronary revascularization. Although there are several potential reasons for the lack of benefit, an underexplored possible reason is the presence of coincidental nonischemic cardiomyopathy (NICM). We investigated the prevalence and prognostic significance of NICM in patients with CAD (CAD-NICM).

METHODS

We conducted a registry study of consecutive patients with obstructive CAD on coronary angiography who underwent contrast-enhanced cardiovascular magnetic resonance imaging for the assessment of ventricular function and scar at 4 hospitals from 2004 to 2020. We identified the presence and cause of cardiomyopathy using cardiovascular magnetic resonance imaging and coronary angiography data, blinded to clinical outcomes. The primary outcome was a composite of all-cause death or heart failure hospitalization, and secondary outcomes were all-cause death, heart failure hospitalization, and cardiovascular death.

RESULTS

Among 3023 patients (median age, 66 years; 76% men), 18.2% had no cardiomyopathy, 64.8% had ischemic cardiomyopathy (CAD+ICM), 9.3% had CAD+NICM, and 7.7% had dual cardiomyopathy (CAD+dualCM), defined as both ICM and NICM. Thus, 16.9% had CAD+NICM or dualCM. During a median follow-up of 4.8 years (interquartile range, 2.9, 7.6), 1116 patients experienced the primary outcome. In Cox multivariable analysis, CAD+NICM or dualCM was independently associated with a higher risk of the primary outcome compared with CAD+ICM (adjusted hazard ratio, 1.23 [95% CI, 1.06-1.43]; P=0.007) after adjustment for potential confounders. The risks of the secondary outcomes of all-cause death and heart failure hospitalization were also higher with CAD+NICM or dualCM (hazard ratio, 1.21 [95% CI, 1.02-1.43]; P=0.032; and hazard ratio, 1.37 [95% CI, 1.11-1.69]; P=0.003, respectively), whereas the risk of cardiovascular death did not differ from that of CAD+ICM (hazard ratio, 1.15 [95% CI, 0.89-1.48]; P=0.28).

CONCLUSIONS

In patients with CAD referred for clinical cardiovascular magnetic resonance imaging, NICM or dualCM was identified in 1 of every 6 patients and was associated with worse long-term outcomes compared with ICM. In patients with obstructive CAD, coincidental NICM or dualCM may contribute to the lack of prognostic benefit from coronary revascularization.

Assessment of myocardial strain patterns in patients with left bundle branch block using cardiac magnetic resonance

Recently, a classification with four types of septal longitudinal strain patterns was described using echocardiography, suggesting a pathophysiological continuum of left bundle branch block (LBBB)-induced left ventricle (LV) remodeling. The aim of this study was to assess the feasibility of classifying these strain patterns using cardiovascular magnetic resonance (CMR), and to evaluate their association with LV remodeling and myocardial scar. Single center registry included LBBB patients with septal flash (SF) referred to CMR to assess the cause of LV systolic dysfunction. Semi-automated feature-tracking cardiac resonance (FT-CMR) was used to quantify myocardial strain and detect the four strain patterns. A total of 115 patients were studied (age 66 ± 11 years, 57% men, 28% with ischemic heart disease). In longitudinal strain analysis, 23 patients (20%) were classified in stage LBBB-1, 37 (32.1%) in LBBB-2, 25 (21.7%) in LBBB-3, and 30 (26%) in LBBB-4. Patients at higher stages had more prominent septal flash, higher LV volumes, lower LV ejection fraction, and lower absolute strain values (p < 0.05 for all). Late gadolinium enhancement (LGE) was found in 55% of the patients (n = 63). No differences were found between the strain patterns regarding the presence, distribution or location of LGE. Among patients with LBBB, there was a good association between strain patterns assessed by FT-CMR analysis and the degree of LV remodeling and LV dysfunction. This association seems to be independent from the presence and distribution of LGE.

Early left bundle branch pacing in heart failure with mildly reduced ejection fraction and left bundle branch block

BACKGROUND

Left bundle branch pacing (LBBP) achieves resynchrony and improves cardiac function in heart failure (HF) patients with reduced ejection fraction (EF) by correcting left bundle branch block (LBBB). Few data on the efficacy of early LBBP in HF with mildly reduced EF (HFmrEF) and LBBB have been reported.

OBJECTIVE

The purpose of this study was to explore the efficacy of early LBBP in patients with HFmrEF and LBBB.

METHODS

Consecutive patients with HFmrEF (left ventricular EF [LVEF] 35%-50%) and LBBB were prospectively enrolled to receive LBBP (Early-LBBP group) plus guideline-directed medical therapy (GDMT) or GDMT alone (GDMT group). Study outcomes included changes in LVEF, LV end-diastolic diameter (LVEDD), New York Heart Association (NYHA) functional classification, and N-terminal pro-brain natriuretic peptide (NT-proBNP), and clinical events (HF rehospitalization or syncope). Subgroup analysis compared efficacy of LBBP between patients with LBBB only without comorbidities or late gadolinium enhancement (LGE) (LBBB-Only group) and patients with either comorbidities or LGE (LBBB-Combined group).

RESULTS

Fifty-four patients were enrolled and analyzed (37 Early-LBBP group; 15 GDMT group). LBBP achieved greater improvement in LVEF (+14.75% ± 7.37% vs -2.42% ± 2.84%; P <.001), reduction of LVEDD (-7.51 ± 5.40 mm vs -0.87 ± 4.36 mm; P <.001) and NYHA classification (-0.84 ± 0.76 vs -0.13 ± 0.74; P = .004), and similar reduction of NT-proBNP (-408.83 ± 920.29 pg/mL vs -229.05 ± 1579.17 pg/mL; P = .610) at 6 months. Early LBBP showed significantly reduced clinical events (0.0% vs 40.0%; P <.001) after 20.68 ± 13.55 months of follow-up. Subgroup analysis showed patients in the LBBB-Only group benefited more from LBBP with regard to LVEF improvement and LVEDD reduction than the LBBB-Combined group.

CONCLUSION

Early LBBP with GDMT demonstrated greater improvement of cardiac function and reduced clinical events than GDMT alone in patients with HFmrEF and LBBB.

CineECG analysis provides new insights into Familial ST-segment Depression Syndrome

AIMS

Familial ST-segment Depression Syndrome (Fam-STD) is a novel inherited cardiac disease associated with arrhythmias and sudden cardiac death. This study aimed at investigating the cardiac activation pathway in patients with Fam-STD, modelling the electrocardiogram (ECG) phenotype, and performing in-depth ST-segment analyses.

METHODS AND RESULTS

CineECG analysis of patients with Fam-STD and age- and sex-matched controls. The groups were compared using the CineECG software which included the trans-cardiac ratio and the electrical activation pathway. We simulated the Fam-STD ECG phenotype by adjusting action potential duration (APD) and action potential amplitude (APA) in specific cardiac regions. High-resolution ST-segment analyses were performed per lead by dividing the ST-segment into nine 10 ms subintervals. Twenty-seven Fam-STD patients (74% females, mean age 51.6 ± 6.2 years) and 83 matched controls were included. Among Fam-STD patients, electrical activation pathway analysis in the anterior-basal orientation showed significantly abnormal direction toward the basal areas of the heart starting from QRS 60-89 ms until Tpeak-Tend (all P < 0.001). Simulations with shortened APD and reduced APA in the left ventricle basal regions recapitulated the Fam-STD ECG phenotype. Detailed ST-segment analyses showed significant differences in all nine 10 ms subintervals (all P < 0.01), with the most prominent findings during the 70-79/80-89 ms intervals.

CONCLUSION

CineECG analyses indicated abnormal repolarization with basal directions, and the Fam-STD ECG phenotype was simulated by reducing APD and APA in the left ventricle basal regions. Detailed ST-analysis showed amplitudes consistent with the proposed diagnostic criteria for Fam-STD patients. Our findings provide new insight into the electrophysiological abnormalities of Fam-STD.

Dyssynchronous Heart Failure: A Clinical Review

PURPOSE OF THE REVIEW

Dyssynchrony occurs when portions of the cardiac chambers contract in an uncoordinated fashion. Ventricular dyssynchrony primarily impacts the left ventricle and may result in heart failure. This entity is recognized as a major contributor to the development and progression of heart failure. A hallmark of dyssynchronous heart failure (HF_d) is left ventricular recovery after dyssynchrony is corrected. This review discusses the current understanding of pathophysiology of HF_d and provides clinical examples and current techniques for treatment.

RECENT FINDINGS

Data show that HF_d responds poorly to medical therapy. Cardiac resynchronization therapy (CRT) in the form of conventional biventricular pacing (BVP) is of proven benefit in HF_d, but is limited by a significant non-responder rate. Recently, conduction system pacing (His bundle or left bundle branch area pacing) has also shown promise in correcting HF_d. HF_d should be recognized as a distinct etiology of heart failure; HF_d responds best to CRT.

Clinical Risk Score to Predict Pathogenic Genotypes in Patients With Dilated Cardiomyopathy

BACKGROUND

Although genotyping allows family screening and influences risk-stratification in patients with nonischemic dilated cardiomyopathy (DCM) or isolated left ventricular systolic dysfunction (LVSD), its result is negative in a significant number of patients, limiting its widespread adoption.

OBJECTIVES

This study sought to develop and externally validate a score that predicts the probability for a positive genetic test result (G+) in DCM/LVSD.

METHODS

Clinical, electrocardiogram, and echocardiographic variables were collected in 1,015 genotyped patients from Spain with DCM/LVSD. Multivariable logistic regression analysis was used to identify variables independently predicting G+, which were summed to create the Madrid Genotype Score. The external validation sample comprised 1,097 genotyped patients from the Maastricht and Trieste registries.

RESULTS

A G+ result was found in 377 (37%) and 289 (26%) patients from the derivation and validation cohorts, respectively. Independent predictors of a G+ result in the derivation cohort were: family history of DCM (OR: 2.29; 95% CI: 1.73-3.04; P < 0.001), low electrocardiogram voltage in peripheral leads (OR: 3.61; 95% CI: 2.38-5.49; P < 0.001), skeletal myopathy (OR: 3.42; 95% CI: 1.60-7.31; P = 0.001), absence of hypertension (OR: 2.28; 95% CI: 1.67-3.13; P < 0.001), and absence of left bundle branch block (OR: 3.58; 95% CI: 2.57-5.01; P < 0.001). A score containing these factors predicted a G+ result, ranging from 3% when all predictors were absent to 79% when ≥4 predictors were present. Internal validation provided a C-statistic of 0.74 (95% CI: 0.71-0.77) and a calibration slope of 0.94 (95% CI: 0.80-1.10). The C-statistic in the external validation cohort was 0.74 (95% CI: 0.71-0.78).

CONCLUSIONS

The Madrid Genotype Score is an accurate tool to predict a G+ result in DCM/LVSD.

Effects of guideline-directed medical therapy in patients with left bundle branch block-induced cardiomyopathy

INTRODUCTION AND OBJECTIVES

Left bundle branch block (LBBB)-induced cardiomyopathy occurs in patients with long-standing LBBB. These patients characteristically exhibit hyperresponsiveness to cardiac resynchronization therapies (CRT). However, there is scarce information on their response to medical treatment. The aim of this study was to assess the change in left ventricular ejection fraction (LVEF) after a 3-month period following titration of guideline-directed medical therapy for heart failure.

METHODS

This retrospective analysis included all patients assessed in the heart failure unit of a Spanish University Hospital between 2020 and 2021, who presented with de novo ventricular dysfunction (LVEF <40%) and had a history of long-standing LBBB with no other possible causes of cardiomyopathy.

RESULTS

A total of 1497 patients were analyzed, of which 21 were finally eligible. Mean time from first diagnosis of LBBB to first consultation was 4.05± 4.1 years. Mean LVEF from first consultation to end of titration improved from 29.5±5.7% to 32.7±8.6% (P = .172), but none had recovered ventricular function at the end of follow-up. New York Heart Association functional class improved from 1.91±0.46 to 1.81±0.53 (P=.542). After CRT device implantation in 8 patients, LVEF improved by 18.1±6.4% (P=.003).

CONCLUSIONS

Guideline-directed medical therapy seems to be ineffective in improving LVEF and functional class in patients with de novo heart failure and LBBB-induced cardiomyopathy. Based on a positive response to CRT on LVEF improvement, early CRT implantation could be a reasonable strategy for these patients.

Left ventricular epicardial pacing achieved hyper-responsiveness in young children with dilated cardiomyopathy with left bundle branch block

Aims

The management of heart failure (HF) in young children is challenging. The present study aimed to clarify the effect of left univentricular epicardial pacing on dilated cardiomyopathy with left bundle branch block (LBBB) in children.

Methods and results

A total of five cases (30.86 ± 16.39 months, three female) of children weighing 5.8–15 kg with dilated cardiomyopathy and LBBB were included in this study. LBBB in one child occurred after device closure of peri‐membranous ventricular septal defects, and the remaining four were idiopathically discovered early after birth. Before implantation, all children suffered from refractory HF and cardiac dilatation; the left ventricular ejection fraction was 33.48 ± 5.84% with Ross Heart Failure Classification III–IV. Electrical and mechanical dyssynchrony were observed in all children with QRS duration >140 ms and prolonged septal‐to‐left posterior wall motion delay. Left univentricular epicardial pacing was successfully implanted via left axillary minithoracotomy in the five children. Sensed atrioventricular delays (83 ± 15 ms) were optimized by velocity time integral of aortic blood flow before discharge. During the follow‐up period (10.8 ± 2.68 months), the dilated failing heart was reversed significantly in terms of decreased left ventricular dimension (55.62 ± 3.46 vs. 38.94 ± 3.69 mm, P = 0.005), while the left ventricular ejection fraction improved to 60.18 ± 8.78% (P = 0.006).

Conclusions

In young children with low body weight, if HF is caused by or related to LBBB, left ventricular epicardial pacing still has an excellent effect.

Prevalence, clinical and instrumental features of left bundle branch block-induced cardiomyopathy: the CLIMB registry

AIMS

Although increasingly recognized as a distinct pathological entity, left bundle branch block-induced cardiomyopathy (LBBB-ICMP) is not included among the possible aetiologies of acquired dilated cardiomyopathies (DCM). While diagnostic criteria have been proposed, its recognition remains principally retrospective, in the presence of clinical and instrumental red flags. We aimed to assess the prevalence and clinical and instrumental features of LBBB-ICMP in a large cohort of patients with DCM.

METHODS AND RESULTS

We analysed a cohort of 242 DCM patients from a two-centre registry. Inclusion criteria were age > 18, non-ischaemic or non-valvular DCM, and LBBB on electrocardiogram. LBBB-ICMP was defined according to previously proposed diagnostic criteria: (i) neither family history nor clinically identifiable potential causes for DCM; (ii) negative genetic testing; (iii) echocardiographic features including non-severe chamber dilation, normal absolute and relative wall thickness, marked dyssynchrony, and normal right ventricular function; and (iv) absence of late gadolinium enhancement (LGE) on cardiac magnetic resonance (CMR). From the entire cohort, we identified 30 subjects (similar in terms of New York Heart Association class I or II in 80% vs. 75%, P = 0.56; QRS width of 150 ± 22 vs. 151 ± 24 ms, P = 0.82; and cardiac remodelling of baseline end-diastolic diameter 66 ± 8 vs. 65 ± 10 mm, P = 0.53) with a comprehensive dataset including CMR and genetic testing, required to verify the presence of the diagnostic criteria proposed for LBBB-ICMP. The main characteristics of this subgroup were 73% males, age 45 ± 13 years, left ventricular ejection fraction (LVEF) 30 ± 10%, LGE in 38% of patients, and QRS complex of 150 ± 22 ms. Patients were under guideline-directed medical therapy, and 57% of them were treated with cardiac resynchronization therapy (CRT). Two patients (6.67%, 50% males, age 53 ± 13 years) fulfilled the diagnostic criteria proposed for LBBB-ICMP. After a follow-up of 44 (12-76) months, LVEF was normal and QRS width significantly reduced (from 154 ± 25 to 116 ± 52 ms) in patients with LBBB-ICMP. Both patients were under optimal medical treatment, and one was implanted with CRT-D. Neither of the two patients experienced death, malignant ventricular arrhythmia, or heart failure hospitalization at follow-up.

CONCLUSIONS

Left bundle branch block-induced cardiomyopathy emerges as a distinct pathological entity, promptly identifiable in a minority but not negligible proportion of patients with newly diagnosed DCM and LBBB, using a series of diagnostic criteria including CMR and genetic testing. Further studies are needed to better elucidate the clinical course of LBBB-ICMP.

Echocardiographic Longitudinal Strain Analysis in Heart Failure: Real Usefulness for Clinical Management Beyond Diagnostic Value and Prognostic Correlations? A Comprehensive Review

Heart failure (HF) is a highly prevalent clinical syndrome characterized by considerable phenotypic heterogeneity. The traditional classification based on left ventricular ejection fraction (LVEF) is widely accepted by the guidelines and represents the grounds for patient enrollment in clinical trials, even though it shows several limitations. Ejection fraction (EF) is affected by preload, afterload, and contractility, it being problematic to express LV function in several conditions, such as HF with preserved EF (HFpEF), valvular heart disease, and subclinical HF, and in athletes. Over the last two decades, developments in diagnostic techniques have provided useful tools to overcome EF limitations. Strain imaging analysis (particularly global longitudinal strain (GLS)) has emerged as a useful echocardiographic technique in patients with HF, as it is able to simultaneously supply information on both systolic and diastolic functions, depending on cardiac anatomy and physiology/pathophysiology. The use of GLS has proved helpful in terms of diagnostic performance and prognostic value in several HF studies. Universally accepted cutoff values and variability across vendors remain an area to be fully explored, hence limiting routine application of this technique in clinical practice. In the present review, the current role of GLS in the diagnosis and management of patients with HF will be discussed. We describe, by critical analysis of the pros and cons, various clinical settings in HF, and how the appropriate use and interpretation of GLS can provide important clues.

Contemporary etiology and prognosis of dilated non-ischemic cardiomyopathy

INTRODUCTION

Non-ischemic dilated cardiomyopathy (NI-DCM) represents a specific etiology of systolic heart failure that usually affect young individuals with a genetic background in up to 40% of cases. Behind the term NI-DCM there is a spectrum of different diseases, and an accurate etiological classification appears pivotal for the clinical management and prognostic stratification of these patients.

EVIDENCE ACQUISITION

In the last years the prognosis of NI-DCM patients dramatically improved thanks to the progresses in medical treatment/ device therapy and earlier diagnosis especially in familial context. In this review we summarize the actual state of art in the management of these patients.

EVIDENCE SYNTHESIS

In the era of precision medicine, a lot of progresses have been made to expand our knowledge on the management of NI-DCM patients. A complex interaction between genotype and external triggers is the main determinant of the clinical phenotype in NI-DCM, and a lot of efforts must be done by clinicians to systematically rule out all the possible causes involved in the pathogenesis. Progresses in cardiac imaging and familial screening led us to detect subtle abnormalities in the initial phase of the disease and also helped us to furtherly stratify the prognosis and arrhythmic risk of these patients. It is plausible that a more precise etiological classification will be needed in the near future.

CONCLUSIONS

NI-DCM contains a spectrum of different diseases. Proper etiological classification, early diagnosis and strict follow-up are essential to tailor care of these patients.

Management of nonischemic-dilated cardiomyopathies in clinical practice: a position paper of the working group on myocardial and pericardial diseases of Italian Society of Cardiology

: Nonischemic-dilated cardiomyopathy (NIDCM) is an entity that gathers extremely heterogeneous diseases. This awareness, although leading to continuous improvement in survival, has increased the complexity of NIDCM patients' management. Even though the endorsed 'red-flags' approach helps clinicians in pursuing an accurate etiological definition in clinical practice, it is not clear when and how peripheral centers should interact with referral centers with specific expertise in challenging scenarios (e.g. postmyocarditis and genetically determined dilated cardiomyopathy) and with easier access to second-line diagnostic tools and therapies. This position paper will summarize each step in NIDCM management, highlighting the multiple interactions between peripheral and referral centers, from first-line diagnostic workup and therapy to advanced heart failure management and long-term follow-up.

Expanding benefits from cardiac resynchronization therapy to exercise-induced left bundle branch block in advanced heart failure

Indications of cardiac resynchronization therapy (CRT) do not include exercise‐induced left bundle branch block, but functional impairment could be improved with CRT in such cases. A 57‐year‐old woman with idiopathic dilated cardiomyopathy (ejection fraction 23%) presented with New York Heart Association Class IV and recurrent hospitalizations. During heart transplant evaluation, a new onset of intermittent left bundle branch block was observed on the cardiopulmonary exercise test. CRT was implanted, and 97% resynchronization rate was achieved. In 12 month follow‐up, both clinical and prognostic exercise parameters improved. In patients with heart failure with reduced ejection fraction and no left bundle branch block at rest, exercise test can uncover electromechanical dyssynchrony that may benefit from CRT.