Biventricular Versus Right Ventricular Pacing in Heart Failure Patients With Atrioventricular Block (BLOCK HF)

Heart failure is a progressive disease that decreases the pumping action of the heart. This
may cause a backup of fluid in the heart and may result in heart beat changes. When there
are changes in the heartbeat, sometimes a pacemaker is used to control the rate and rhythm
of the heartbeat. In this trial, the researchers will test if pacing both the left and
right lower half of the heart (ventricles) will:

- decrease the number of hospital and clinic visits due to heart failure symptoms

- extend life

- delay heart failure symptoms as compared to those who are paced in only one ventricle
(the right ventricle)