Biventricular Pacing In Patients With Left Ventricular Dysfunction After Cardiovascular Surgery

Congestive heart failure (CHF) is a medical condition that is due to left ventricular systolic dysfunction (LVSD). LVSD is a decreased ability of the heart to pump blood forward. There are 5 million people in the United States that have CHF and 52,828 new cases are diagnosed annually. There are 995,000 hospital visits and 52,828 deaths annually due to CHF. Previous studies have shown that people with this condition are at a higher risk for complications immediately after any type of heart surgery than are normal individuals. This includes increased dependence on medications and devices to improve the pumping function of the heart and blood pressure. Additionally, they also have longer lengths of hospital stay and higher rates of death compared to normal individuals.

Some patients with LVSD not only have a decreased pumping ability of the heart, they also have an inefficient pumping function. These patients have been shown to benefit from a device therapy known as biventricular pacing. Biventricular pacing involves simultaneously electrically stimulating the two major pumping chambers of the heart known as ventricles using a pacemaker and wires. This causes a more coordinated contraction of the heart chambers resulting in improvement in the pumping ability of the heart and blood pressure. Studies have confirmed that in these patients, implantation of a biventricular pacemaker improves patients' symptoms and quality of life as well as decreasing a need for future hospitalizations. Whether biventricular pacing in patients with LVSD improves patient outcomes after heart surgery has not been investigated.

Some patients temporarily develop slow heart rates after cardiovascular surgery. These slow heart rates can cause a decrease in the blood pumped from the heart and result in low blood pressures. Therefore, all patients undergoing cardiovascular surgery, regardless of left ventricular function, receive temporary pacing wires that are placed on one of the ventricles during the surgery. Temporary pacing will result in an increase in heart rate and improvement in the amount of blood pumped by the heart and in blood pressure. The placement of these wires is precautionary as only a few patients need to be paced for slow heart rates. Once patients are felt to no longer require them, the wires are easily removed. The purpose of this study is to determine whether biventricular pacing immediately after heart surgery in patients with LVSD will improve in-hospital outcomes.

Patients that are scheduled for heart surgery and meet the inclusion criteria will be approached for consent to participate in this study. Once consented, they will be randomized to one of three treatment arms: usual care, RV pacing (single ventricle pacing), or biventricular pacing. Randomization is a process similar to picking numbers out of a hat. The patients will then undergo surgery as scheduled. During the surgery, the patients will receive the temporary pacing wires on both ventricles instead of one. Immediately after surgery, the patients will receive either usual care, RV pacing, or biventricular pacing depending upon the treatment arm that they were randomized to. The pacing wires will be removed as soon as the patients become stable as per routine. The clinical, operative, and in-hospital characteristics of these patients will be recorded on specialized forms. The characteristics of those that received biventricular pacing will be compared to those that had RV or no pacing to see whether there was any benefit to this mode of therapy.