Updated guidelines on device-based treatment for cardiac rhythm abnormalities include several changes in the use of cardiac resynchronization therapy, according to a report issued jointly by the American College of Cardiology Foundation, the American Heart Association, and the Heart Rhythm Society and published online Sept. 10 in Circulation.
The most significant changes are the expanded use of cardiac resynchronization therapy (CRT) to include patients with mild heart failure (New York Heart Association class II) and to patients with particular ECG abnormalities indicating irregular, slow rhythms, said Dr. Cynthia M. Tracy, chair of the guideline writing group and director of electrophysiology at George Washington University, Washington, and her associates.
"These are patients who had previously been excluded from receiving CRT, but studies have shown they can benefit from this procedure. It can really improve their lives by delaying or avoiding worsening heart failure," she said in a press statement accompanying the update.
The guidelines also now reflect the "growing evidence that patients with the widest, most abnormal–looking ECG potentially benefit most, compared with patients whose ECG is less abnormal." In particular, patients with left bundle branch block and a QRS duration of 150 milliseconds or more appear to benefit greatly from CRT, she noted.
The updated guidelines are also being published in the Journal of the American College of Cardiology and Heart Rhythm. They were developed in collaboration with the American Association for Thoracic Surgery, the Heart Failure Society of America, and the Society of Thoracic Surgeons.
The original guidelines on devise-based treatment of cardiac rhythm abnormalities were issued in 2008. The updated guidelines "extend and clarify current best practices and will continue to evolve as technology advances," Dr. Tracy added.
In the updated guidelines, the class I recommendations for CRT have been expanded to include patients with milder heart failure. But these, as with all other class I recommendations, are limited to those with left bundle branch block and a QRS of 150 milliseconds or more. In addition, a class IIb recommendation for CRT has been added for patients with aleft ventricular ejection fraction (LVEF) of 30% or less, an ischemic etiology of their heart failure (HF), sinus rhythm, left bundle branch block with a QRS duration of 150 milliseconds or more, and functionally mild HF, Dr. Tracy and her colleagues said (Circulation 2012 Sept. 10 [doi:10.1161/CIR.0b013e3182618569]).
Regarding terminal care, the recommendations "on management of cardiovascular implantable electronic devices in patients nearing the end of life or requesting withdrawal of therapy were expanded upon ... in an effort to provide guidance to caregivers dealing with this increasingly prevalent and difficult issue," according to the update.
This change was prompted by the observation that more such patients are surviving longer – long enough to develop comorbid conditions such as dementia or malignancy, which may take precedence over their rhythm abnormality.
Remote follow-up and monitoring of cardiovascular implantable electronic devices – including pacemakers, implantable cardioverter defibrillators, CRTs, implantable loop recorders, and implantable cardiovascular monitors – also has changed dramatically since the 2008 guidelines were formulated. "The standard approach was routine in-person office follow-up supplemented by transtelephonic monitoring with limited remote follow-up," but that approach is now considered "dated."
In contrast, "contemporary remote monitoring uses bidirectional telemetry with encoded and encrypted radiofrequency signals, allowing transmission and receipt of information from [these devices]." Many devices use wireless cellular technology to extend telemetry links to wherever the patient is located and to allow clinicians to access the data through the Internet. Almost all of the information that could be obtained in an in-office visit now is available remotely, including battery voltage, ICD charge time, percent pacing, sensing thresholds, automatically measured pacing thresholds, pacing and shock impedance, and stored arrhythmia events with ECGs, Dr. Tracy and her colleagues said.
No changes have been made in guideline recommendations regarding ICD implantation for arrhythmogenic right ventricular dysplasia/cardiomyopathy, asymptomatic genetic arrhythmia syndromes, primary prevention of sudden cardiac death in patients with congenital heart disease and advanced ventricular dysfunction, idiopathic ventricular fibrillation, short QT syndrome, Brugada syndrome, or catecholaminergic polymorphic ventricular tachycardia.
The full text of the update guidelines is available on the websites of the American College of Cardiology, the American Heart Association, and the Heart Rhythm Society.