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

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.

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.

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.

Heart failure: an update from the last years and a look at the near future

In the last years, major progress occurred in heart failure (HF) management. Quadruple therapy is now mandatory for all the patients with HF with reduced ejection fraction. Whilst verciguat is becoming available across several countries, omecamtiv mecarbil is waiting to be released for clinical use. Concurrent use of potassium-lowering agents may counteract hyperkalaemia and facilitate renin-angiotensin-aldosterone system inhibitor implementations. The results of the EMPagliflozin outcomE tRial in Patients With chrOnic heaRt Failure With Preserved Ejection Fraction (EMPEROR-Preserved) trial were confirmed by the Dapagliflozin in Heart Failure with Mildly Reduced or Preserved Ejection Fraction (DELIVER) trial, and we now have, for the first time, evidence for treatment of also patients with HF with preserved ejection fraction. In a pre-specified meta-analysis of major randomized controlled trials, sodium-glucose co-transporter-2 inhibitors reduced all-cause mortality, cardiovascular (CV) mortality, and HF hospitalization in the patients with HF regardless of left ventricular ejection fraction. Other steps forward have occurred in the treatment of decompensated HF. Acetazolamide in Acute Decompensated Heart Failure with Volume Overload (ADVOR) trial showed that the addition of intravenous acetazolamide to loop diuretics leads to greater decongestion vs. placebo. The addition of hydrochlorothiazide to loop diuretics was evaluated in the CLOROTIC trial. Torasemide did not change outcomes, compared with furosemide, in TRANSFORM-HF. Ferric derisomaltose had an effect on the primary outcome of CV mortality or HF rehospitalizations in IRONMAN (rate ratio 0.82; 95% confidence interval 0.66-1.02; P = 0.070). Further options for the treatment of HF, including device therapies, cardiac contractility modulation, and percutaneous treatment of valvulopathies, are summarized in this article.

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.

A year in heart failure: an update of recent findings

Major changes have occurred in these last years in heart failure (HF) management. Landmark trials and the 2021 European Society of Cardiology guidelines for the diagnosis and treatment of HF have established four classes of drugs for treatment of HF with reduced ejection fraction: angiotensin‐converting enzyme inhibitors or an angiotensin receptor‐neprilysin inhibitor, beta‐blockers, mineralocorticoid receptor antagonists, and sodium‐glucose co‐transporter 2 inhibitors, namely, dapagliflozin or empagliflozin. These drugs consistently showed benefits on mortality, HF hospitalizations, and quality of life. Correction of iron deficiency is indicated to improve symptoms and reduce HF hospitalizations. AFFIRM‐AHF showed 26% reduction in total HF hospitalizations with ferric carboxymaltose vs. placebo in patients hospitalized for acute HF (P = 0.013). The guanylate cyclase activator vericiguat and the myosin activator omecamtiv mecarbil improved outcomes in randomized placebo‐controlled trials, and vericiguat is now approved for clinical practice. Treatment of HF with preserved ejection fraction (HFpEF) was a major unmet clinical need until this year when the results of EMPEROR‐Preserved (EMPagliflozin outcomE tRial in Patients With chrOnic HFpEF) were issued. Compared with placebo, empagliflozin reduced by 21% (hazard ratio, 0.79; 95% confidence interval, 0.69 to 0.90; P < 0.001), the primary outcome of cardiovascular death or HF hospitalization. Advances in the treatment of specific phenotypes of HF, including atrial fibrillation, valvular heart disease, cardiomyopathies, cardiac amyloidosis, and cancer‐related HF, also occurred. Coronavirus disease 2019 (COVID‐19) pandemic still plays a major role in HF epidemiology and management. All these aspects are highlighted in this review.