PITA-HF: Feasibility, Safety, and Tolerability

Heart failure affects over 25 million people worldwide and nearly 7 million adults in the United States alone. Nearly 25% of patients with heart failure have worsened disease burden from dyssynchronous ventricular contraction due to abnormal electrical impulse propagation. These patients may benefit from cardiac resynchronization therapy (CRT) where contraction between the ventricles is coordinated by simultaneous electrical stimulation of the right and left ventricles. In animal models, CRT changes molecular and cellular biology by improving myofilament function, ion channel regulation, beta-receptor signaling, and overall mitochondrial energetics. In randomized clinical outcomes trials, the use of CRT further reduced the incidence of heart failure events and improved overall mortality. However, nearly 75% of patients with heart failure have synchronous ventricular contraction and therefore do not qualify for CRT. CRT profoundly alters underlying molecular and cellular biology as a result of the transition from dyssynchronous to resynchronized contraction, enhancing myocyte function and adrenergic responsiveness. The investigators previously hypothesized CRT-like benefits could be achieved in otherwise synchronous heart failure by purposely inducing dyssynchrony for several hours each day and then reversing this for the remainder of the time. The investigators termed this pacemaker induced transient dyssynchrony, or PITA, and tested its impact in a canine dilated cardiomyopathy model. Following several weeks of rapid atrial pacing to induce heart failure in the animals, the investigators compared implementing 4-weeks of PITA - consisting of dyssynchronous rapid right ventricular pacing for 6 hours each night and atrial pacing for the remaining time - to animals that always received rapid atrial pacing. The fast rate is used to generate a heart failure phenotype. PITA improved chamber dilation, increased beta-adrenergic responsiveness and contractile function, and i