Biventricular Pacing 

Recent reports are suggesting that biventricular pacing may offer some important options in the treatment of CHF patients. A significant percentage of patients with CHF have conduction abnormalities on ECG. These conduction abnormalities result in abnormal activation of ventricular myocardium and asynchronous activation of the atrial and ventricular chambers. Biventricular pacing attempts to activate the right and left venticles simultaneously, producing what is termed "ventricular resynchronization". This therapy was discussed extensively in the July, 1999 issue of the Arrhythmia News.

Studies have confirmed acute and short-term hemodynamic benefits of biventricular pacing. In addition, studies have documented improvement in the functional status of patients with CHF. Larger, prospective studies investigating the beneficial effects of biventricular pacing and its clinical implications are currently underway. The Arrhythmia Service at St. Luke's-Roosevelt Hospital Center, in conjunction with the Heart Failure Service, has been and continues to be an active participant in these trials.

Mortality in Heart Failure 

Despite advances in heart failure therapy, mortality remains high in patients with CHF and increases with worsening functional status. Pertinent to the discussion of biventricular pacing is the fact that CHF patients with significant conduction abnormalities represent a high-risk subgroup within the CHF population with significantly increased mortality.

Ventricular arrhythmias are ubiquitous in the CHF population; 40-50% of deaths in CHF are sudden and presumably the result of these arrhythmias. In addition, sudden death is responsible for a larger proportion of deaths in CHF patients with a better functional status: 50-80% of patients with NYHA Class II CHF die suddenly as compared to 5-30% of patients with NYHA Class IV. As a result of these striking statistics, physicians increasing seek implantable cardioverter-defibrillator (ICD) therapy for their patients with CHF. However, it must be noted that the role of the ICD as primary therapy in improving survival has not yet been confirmed and is not yet considered standard therapy for CHF patients in the absence of documented sustained ventricular arrhythmias.

Potential Survival Benefit with Biventricular Pacing 

In addition to the symptomatic and functional improvements, other important changes have been noted in CHF patients treated with biventricular pacing. Parameters of cardiac function such as left ventricular dimensions and myocardial performance index have improved markedly. Elevated plasma norepinephrine levels, which are associated with increased mortality in CHF, improve in biventricular pacing. Decreased heart rate variability, also associated with increased risk of sudden death in CHF, has been shown to improve. These findings have lead investigators to hypothesize the potential for biventricular pacing to improve survival. This being said, no trial to date has demonstrated a survival benefit to biventricular pacing.

COMPANION Trial 

For biventricular pacing to become standard therapy for CHF, studies demonstrating a reduction in hospitalization and improvements in all-cause mortality will be a necessity. The COMPANION Trial, in which the Arrhythmia Service together with the Heart Failure Service at St. Luke's-Roosevelt Hospital Center have begun participation, is the first trial of biventricular pacing to date to evaluate this endpoint. The study seeks to enroll 2200 patients with NYHA Class III or IV heart failure who have LVEF <35%, LV end diastolic dimension >60 mm and a QRS duration >120 ms. All patients must be on optimal medical therapy for heart failure, defined as loop diuretics, spironolactone, beta-blockers and ACE inhibitors. Patients participating in the trial will be randomized to one of three treatment arms: 1) conventional heart failure therapy alone, 2) conventional heart failure therapy with biventricular pacing, and 3) conventional heart failure therapy with biventricular pacing/ICD. Randomization will occur in a 1:2:2 ratio for the above therapies. Thus, 80% of enrollees receive a biventricular pacing device. The study, which is sponsored by Guidant, is designed to obtain 3-year follow-up in all patients. Referring physicians with patients who qualify for the COMPANION Trial are encouraged to contact the Arrhythmia Service offices at 212-523-4025

The COMPANION Trial
Inclusion Criteria
NYHA Class III or IV heart failure
LVEF <35%
LV end diastolic dimension >60 mm
QRS duration >120 ms
Optimal medical therapy for heart failure
(diuretics, spironolactone, beta-blockers, ACE inhibitors)

Randomized Treatments (ratio 1:2:2)
Optimal heart failure therapy alone
Biventricular pacing + optimal CHF therapy
Biventricular pacing/ICD + optimal CHF therapy

Conference to Highlight Outpatient Management of Atrial Fibrillation

Outpatient Management Strategies for Atrial Fibrillation is the focus of the annual Diagnosis and Management of Arrhythmias conference, sponsored by the Arrhythmia Service of St. Luke's Roosevelt Hospital.

In addition to Arrhythmia Service faculty, guest faculty for the this year's conference will include Dr. Steven Singh from Georgetown University, who will discuss "The Value of New Antiarrhythmic Medications", and Dr. Anne Curtis from the University of Florida, who will discuss "Who Should be Referred For Catheter Ablation".

The conference will be held Saturday, May 12, 2001, in the Conference Center at Roosevelt Hospital in New York City. For information contact the CME office at 212-523-2138 or the Arrhythmia Service at 212-523-4017.

Reproduced with permission. Published by the Arrhythmia Service of St. Luke's-Roosevelt Hospital Center, New York, New York.