Impact of left bundle branch block in patients with takotsubo cardiomyopathy

Abstract

Background Takotsubo cardiomyopathy (TCM) is a syndrome characterized by reversible left-ventricular regional systolic dysfunction in the absence of obstructive coronary artery disease (CAD). The presence of left bundle branch block (LBBB) has been described as an independent predictor of mortality in patients with CAD. One study using the National Inpatient Sample (NIS) for 2016 found that the presence of LBBB was associated with worse outcomes in patients with TCM. Purpose To better clarify the association between LBBB and various in-hospital outcomes in patients with TCM. Methods The NIS database was queried from 2016–2019 to identify all admissions with a primary diagnosis of TCM that had a cardiac catheterization to improve the specificity of the diagnosis. International classification of diseases, tenth revision clinical modification (ICD-10-CM) codes were used to divide patients based on the presence or absence of LBBB. A 1:3 propensity score matching based on age, race, gender, and risk factor stratification was used to reduce selection bias. Multivariate linear and logistic regression analysis was performed to compare various outcomes among both groups. Results A total of 27,125 patients admitted with a primary diagnosis of TCM that also underwent diagnostic coronary angiography were identified. In the study sample, 955 (3.5%) were determined to have a LBBB. After calculating propensity scores, 955 patients with LBBB were paired to 2,865 patients without LBBB. LBBB was associated with higher rates of ventricular arrhythmias (AOR=3.098, 95% CI 1.483–6.471, p=0.003); however, it was not statistically associated with cardiogenic shock, sudden cardiac arrest (SCA), acute kidney injury, acute heart failure, and hospital length of stay. In addition, there was no statistical difference in intra-hospital mortality. Conclusions LBBB is associated with left ventricular dyssynchrony. It has been proposed that intraventricular dyssynchrony might be a predisposing factor for ventricular arrhythmias (VA) and SCA. Several trials have demonstrated that cardiac resynchronization therapy alone (i.e., without defibrillation) reduces the rate of VA and SCA. The mechanism for this improvement is unclear but may be related to hemodynamic improvement from ventricular synchrony in heart failure (HF). In fact, LBBB has been reported as an independent risk factor for all-cause mortality and SCA at one year in patients with HF. Our analysis did not find any significant association between LBBB and SCA but did find an association with VA. Moreover, there were not enough events of intra-hospital mortality to assess a possible association between LBBB and mortality. Therefore, a prospective study with a longer follow-up would be needed to clarify the role of LBBB in mortality and establish causality between LBBB and VA in patients with TCM. Funding Acknowledgement Type of funding sources: None.