Arrhythmias in heart failure-Where the past meets the future.

Welcome to the Heart Rhythm O Special Issue Arrhythmias in Heart Failure. This issue includes 8 original articles, 1 case report, and 9 review papers, covering topics of patient evaluation, device implant and management, and ablation for both ventricular and atrial arrhythmias.

Tremendous changes have occurred over the past decade in the management of patients with heart failure (HF) and coexisting arrhythmias. The years encompassing the early 2000s firmly established the implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy (CRT) as life-saving therapies for patients with reduced left ventricular ejection fraction heart failure (HFrEF). The final primary prevention trial of that era was the Sudden Cardiac Death in Heart Failure Trial (SCD-HEFT), which demonstrated a survival benefit of ICD therapy for patients with both an ischemic and nonischemic cause of HF.

CRT with or without a defibrillator in multiple large, randomized trials was demonstrated to improve survival and measures of cardiac function and to reduce HF hospitalizations across the spectrum of HFrEF (NYHA class I–IV). Nonetheless, not all patients benefit equally from these device therapies. This was most dramatically demonstrated in the MADIT CRT, where patients with a non–left bundle branch QRS morphology had no benefit. Furthermore, not all “ideal” CRT candidates receive benefit.

It was not until the DANISH trial was published that new information was added to the body of randomized clinical trials examining the role of an ICD in HF patients. This study focused on nonischemic HF patients and did not show a survival benefit of the ICD. There was a high use of CRT (∼60%) in both randomized groups and a high use of guideline-directed medical therapy (GDMT) for HFrEF. The critical role for GDMT remains a fundamental tenet in treating HFrEF, including the addition of new therapies targeting other maladaptive mechanisms. The use of angiotensin-converting enzyme inhibitors or aldosterone receptor blockers, beta blockers, and mineralocorticoid antagonists has been shown to reduce sudden death mortality by 60%. In addition, the beneficial effect of sacubitril/valsartan and, more recently, the promise of sodium-glucose co-transporter-2 (SGLT2) inhibitors provide substantial evidence that GDMT reduces all-cause, HF, and sudden death mortality to levels heretofore not seen.

It is therefore more important than ever to identify patients with a proportionally high risk of sudden cardiac death and tailor ICD therapy to those who most may benefit. Novel therapy such as conduction system pacing or endovascular left ventricular electrodes may move the needle towards improving CRT benefit.

The management of recurrent ventricular tachyarrhythmias in HF patients can be challenging. Antiarrhythmic drugs are limited by side effects and reduced efficacy. Frequent ventricular tachycardia (VT) can worsen HF and patients often experience ICD shocks, which, while generally effective, produce significant anxiety. VT ablative therapy can be effective to reduce recurrent episodes of VT and may improve survival in selected populations. Maturation of technology and technique have promoted the use of VT ablation early in the course of a patient’s recurrent VT. The importance of high premature ventricular contraction (PVC) burden is recognized to worsen or cause HFrEF, and a more aggressive use of PVC ablation is supported by societal guidelines.

Atrial fibrillation (AF) is associated with worsened heart failure and stroke risk. The evolution of catheter ablative therapies has led to use of catheter ablation as first-line or secondary therapy for patients with symptomatic paroxysmal AF. Ablation of AF in HF patients was demonstrated to improve survival in the CASTLE AF trial. In a post hoc analysis of the CABANA trial, mortality was decreased in a population of HF patients that was dominated by patients with preserved or mid-range ejection fraction HF.

Patients with HF now live longer and live better than 20 years ago—in part owing to improved arrhythmia therapies developed and tested over these years. Still, there is more work to be done to improve efficacy and safety of HF therapies, marching ever closer to the Heart Rhythm Society’s vision: To end death and suffering due to heart rhythm disorders.

Enjoy this December Special Issue of Heart Rhythm O!

Jeanne E. Poole, MD, FHRS

Editor-in-Chief, Heart Rhythm O