The following are key points to remember from this state-of-the-art review on electrical management of heart failure:

1. There are four distinct types of electrical cardiomyopathy: tachymyopathy, irregulopathy, atrioventricular (AV) dissociation, and cardiac dysfunction caused by nonsynchronous ventricular activation.
2. Irregular rhythm may be the result of premature ventricular contractions (PVCs), premature atrial contractions (PACs), and atrial fibrillation (AF). Irregular rhythm results in post-extrasystolic potentiation, characterized by Ca²⁺ overload, and altered profile of gene and protein expression.
3. Ventricular dyssynchrony is present when ventricular activation occurs outside the normal conduction system, such as in left bundle branch block (LBBB), ventricular tachycardia (VT), chronic right ventricular pacing, pre-excitation syndrome, and PVCs.
4. The mechanism of tachymyopathy is multifactorial, including subclinical ischemia due to underperfusion caused by short diastolic periods and reduced blood pressure combined with increased demands, abnormalities in cellular energetics, redox stress, and calcium overload.
5. AV dissociation can be complete (random intervals between the atrial and ventricular contraction) or a constantly prolonged interval between the two (in the case of a persistently prolonged PR interval on the electrocardiography).
6. Tachycardia-mediated cardiomyopathy may be due to AF, atrial flutter, atrial tachycardia, or permanent junctional reciprocating tachycardia. The diagnosis should be suspected in patients with left ventricular (LV) dysfunction, absence of other etiology, and confirmed by the recovery of the LV function following the initiation of antiarrhythmic drug or ablation treatment. Despite the resolution of the LV function, myocardial fibrosis may remain and contribute to sudden cardiac death in patients with VT despite the resolution of cardiomyopathy.
7. PVC-mediated cardiomyopathy generally requires frequent (>5-10%) PVCs. PVCs with longer QRS duration and epicardial location are more often associated with PVC cardiomyopathy. Absence or minimal scar burden and well as unifocal PVCs are more often associated with PVC-mediated cardiomyopathy than in patients with cardiomyopathy producing PVCs. PVC ablation is usually preferred to antiarrhythmic therapy due to its greater efficacy in a select group of patients.
8. Several prospective randomized clinical trials showed that AF ablation in patients with LV dysfunction may be preferable to medical therapy to improve LV function. AV nodal ablation and pacemaker implantation should be considered when medication for rate control fails, especially in combination with cardiac resynchronization therapy (CRT) for patients with reduced LV function.
9. The largest benefit of CRT is commonly observed in patients with a ‘true’ LBBB and no evidence of ischemic heart disease, and commonly women. Improvement of patient selection with the use of echocardiographic markers of mechanical dyssynchrony has not been consistently demonstrated. Recently evolving and physiologically superior approaches to resynchronization are endocardial CRT, His bundle pacing, left bundle pacing, and deep LV septal pacing.
10. There are significant gender differences in the application of various therapies, with women being less likely than men to receive AF ablation, implantable cardioverter-defibrillator, and CRT implants. Interestingly, women are more likely to both benefit from CRT and have higher complication rates.

Clinical Topics: Arrhythmias and Clinical EP, Heart Failure and Cardiomyopathies, Noninvasive Imaging, Implantable Devices, EP Basic Science, SCD/Ventricular Arrhythmias, Atrial Fibrillation/Supraventricular Arrhythmias, Acute Heart Failure, Echocardiography/Ultrasound

Keywords: Anti-Arrhythmia Agents, Arrhythmias, Cardiac, Atrial Fibrillation, Atrial Flutter, Atrial Premature Complexes, Blood Pressure, Bundle-Branch Block, Cardiac Resynchronization Therapy, Cardiomyopathies, Catheter Ablation, Death, Sudden, Cardiac, Defibrillators, Implantable, Echocardiography, Electrocardiography, Heart Failure, Myocardial Ischemia, Pacemaker, Artificial, Pre-Excitation Syndromes, Tachycardia, Ventricular, Ventricular Dysfunction, Left, Ventricular Premature Complexes

< Back to Listings