Leave the Pill in the Pocket: Can the Pacemaker Alone Improve Heart Failure?

Cardiac resynchronization therapy is currently indicated to prevent electrical and mechanical dyssynchrony in the setting of wide QRS, symptomatic heart-failure and severely reduced ejection fraction (EF) ≤ 35%. The benefit is greatest if the wide QRS is due to left bundle branch block (LBBB). 1 Tracy C.M. Epstein A.E. Darbar D. et al. 2012 ACCF/AHA/HRS focused update of the 2008 guidelines for device-based therapy of cardiac rhythm abnormalities: A report of the American college of cardiology foundation/american heart association task force on practice guidelines. Circulation. 2012; 126: 1784-1800https://doi.org/10.1161/CIR.0b013e3182618569 Crossref PubMed Scopus (262) Google Scholar ,2 Gold M.R. Thébault C. Linde C. et al. Effect of QRS duration and morphology on cardiac resynchronization therapy outcomes in mild heart failure: Results from the resynchronization reverses remodeling in systolic left ventricular dysfunction (REVERSE) study. Circulation. 2012; 126: 822-829https://doi.org/10.1161/CIRCULATIONAHA.112.097709 Crossref PubMed Scopus (242) Google Scholar In patients with EFs between 36% - 50% and AV block; and are expected to require ventricular pacing >40% of the time, CRT or physiologic pacing is indicated to prevent heart failure. 3 Barrett C. FhrsA Kenneth Ellenbogen et al. James Edgerton FahaR2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2019; 74: e51-e156https://doi.org/10.1016/J.JACC.2018.10.044 Crossref Google Scholar ,4 Curtis A.B. Worley S.J. Adamson P.B. et al. Biventricular Pacing for Atrioventricular Block and Systolic Dysfunction. N Engl J Med. 2013; 368: 1585-1593https://doi.org/10.1056/NEJMOA1210356/SUPPL_FILE/NEJMOA1210356_DISCLOSURES.PDF Crossref PubMed Scopus (0) Google Scholar LBBB is associated with developing cardiomyopathy even in the setting of preserved EF. 5 Sharma S. Barot H.V. Schwartzman A.D. et al. Risk and predictors of dyssynchrony cardiomyopathy in left bundle branch block with preserved left ventricular ejection fraction. Clin Cardiol. 2020; 43: 1494https://doi.org/10.1002/CLC.23467 Crossref Google Scholar In a study by Barrett et al. goal directed medical therapy (GDMT) for chronic systolic heart failure in patients with LBBB when compared to narrow QRS the EF did not significantly improve at 3 months. 3 Barrett C. FhrsA Kenneth Ellenbogen et al. James Edgerton FahaR2018 ACC/AHA/HRS Guideline on the Evaluation and Management of Patients With Bradycardia and Cardiac Conduction Delay: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines and the Heart Rhythm Society. J Am Coll Cardiol. 2019; 74: e51-e156https://doi.org/10.1016/J.JACC.2018.10.044 Crossref Google Scholar When these patients underwent CRT, a significant portion of patients were super responders indicating the role of LBBB as a causative mechanism for cardiomyopathy. 6 Wang N.C. Singh M. Adelstein E.C. et al. New-onset left bundle branch block–associated idiopathic nonischemic cardiomyopathy and left ventricular ejection fraction response to guideline-directed therapies: The NEOLITH study. Hear Rhythm. 2016; 13: 933-942https://doi.org/10.1016/J.HRTHM.2015.12.020 Abstract Full Text Full Text PDF Google Scholar Left bundle branch pacing (LBBP) is feasible and safe as a primary pacing technique for both bradycardia and heart failure and low and stable thresholds over time make it a more desirable way to achieve conduction system pacing compared to His bundle pacing.7,8,9,10 It is unclear however, if correcting this LBBB with left bundle branch pacing (LBBP) would also improve ejection fraction when compared with GDMT alone in mildly reduced EF or preserved EF population. This is the question the authors have tried to answer. Diabetes Mellitus and Cardiovascular Disease: An Evidence-Based Review of Provincial Formulary CoverageCanadian Journal of CardiologyVol. 34Issue 10PreviewCardiovascular mortality is the primary cause of death in patients with type 2 diabetes mellitus (T2DM). Recently, clinical trials of the sodium-glucose transport protein 2 (SGLT-2) inhibitors empagliflozin and canagliflozin and of the glucagon-like peptide-1 (GLP-1) agonists liraglutide and semaglutide demonstrated that the agents reduced cardiovascular events. Furthermore, empagliflozin and liraglutide reduced cardiovascular mortality. However, despite the proven cardiac benefits, many but not all provincial formularies have restrictive rules for payment and access for SGLT-2 inhibitors and GLP-1 agonists. Full-Text PDF