Spontaneous resolution of left bundle branch block and biventricular stimulation lead to reverse remodeling in dyssynchronopathy

Reversible complete left bundle branch block and a wide QRS complex following administration of sodium-glucose cotransporter-2 inhibitor and volume reduction in a patient with systolic heart failure: a case report

Background

Guidelines recommend optimal medical therapy before cardiac resynchronization therapy (CRT) implantation. Herein, we report the potential effect of sodium-glucose cotransporter-2 inhibitors (SGLT2is) in improving the QRS duration and volume reduction in a patient with complete left bundle branch block (CLBBB) and reduced cardiac function.

Case summary

A 68-year-old man with a history of ischaemic cardiomyopathy and decreased cardiac function had exacerbation of heart failure (HF) at an outpatient clinic. His QRS duration increased remarkably with a CLBBB of 143 ms on an electrocardiogram, and left ventricular desynchrony was assessed by echocardiography, suggesting an indication of CRT implantation. Administration of an SGLT2i and multimodal treatment for HF stabilized his HF condition and improved the QRS duration and volume reduction thereafter. The CLBBB recovered to incomplete LBBB with a QRS duration of 112 ms on electrocardiography after 6 months. The patient has been stably followed up with continuous medications, including SGLT2i, without requiring CRT implantation or worsening of HF for 12 months.

Discussion

This case presents a unique scenario wherein electrical and mechanical reverse remodelling occurred in a patient with systolic HF and CLBBB, highlighting the potential benefits of SGLT2i in HF management. It may be important to carefully consider CRT indications when seeking other options to treat HF conditions and recognize an unusual phenomenon of reverse LBBB in clinical cases.

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.

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

Despite being increasingly recognized as a specific disease, at the present time left bundle branch block (LBBB)-induced cardiomyopathy is neither formally included among unclassified cardiomyopathies nor among the acquired/non-genetic forms of dilated cardiomyopathy (DCM). Currently, a post-hoc diagnosis of LBBB-induced cardiomyopathy is possible when evaluating patients' response to cardiac resynchronization therapy (CRT). However, an early detection of a LBBB-induced cardiomyopathy could have significant clinical and therapeutic implications. Patients with the aforementioned form of dyssynchronopathy may benefit from early CRT and overall prognosis might be better as compared to patients with a primary muscle cell disorder (i.e. "true" DCM). The real underlying mechanisms, the possible genetic background as well as the early identification of this specific form of DCM remain largely unknown. In this review the complex relationship between LBBB and left ventricular non-ischaemic dysfunction is described. Furthermore, a multiparametric approach based on clinical, electrocardiographic and imaging red flags, is provided in order to allow an early detection of the LBBB-induced cardiomyopathy.

Transient left bundle branch block and intraventricular dyssynchrony as a cause of reversible left ventricular dysfunction: The "in vivo" documentation of spontaneous electrical remodeling

Spontaneous resolution of non-rate-dependent left bundle branch block (LBBB) has been rarely reported. We present the case of a 74-year-old woman admitted with pulmonary edema, a newly diagnosed LBBB and severe left ventricular (LV) dysfunction. Five months later, the patient was asymptomatic, the ECG recording showed complete regression of the LBBB to narrow QRS and LV function completely recovered. However, at one-year follow-up LBBB reappeared together with mild LV dysfunction. Spontaneous resolution of LBBB may be responsible for LV electrical and mechanical reverse remodeling in dyssynchronopathies.

Heart rate reduction after ivabradine might be associated with reverse electrical remodeling in patients with cardiomyopathy and left bundle branch block

Left bundle branch block increases the risk of death in patients with chronic heart failure. We herein report four clinical cases of patients with chronic heart failure caused by nonischemic cardiomyopathy with left bundle branch block that occurred when adding ivabradine to optimal medical therapy, resulting in reverse electrical and mechanical remodeling. This phenomenon might be explained by the effect of ivabradine on reverse remodeling of the left ventricle with improvement of intraventricular conduction.