Optimizing cardiac resynchronization therapy in heart failure patients by measuring transient changes in sinus rate during pacing

To optimize cardiac resynchronization therapy (CRT) for chronic heart failure (CHF) patients, acute studies show that left ventricular pacing site and atrio-ventricular (AV) delay can be individualized to maximize aortic pulse pressure (PP) increase. In the normal patient it is known that atrial cycle length (ACL) increases as PP increases via the baroreceptor reflex. Therefore, we evaluated another parameter for optimization of pacing parameters - transient ACL, or inversely, sinus heart rate. In a retrospective study, 29 CHF patients, acutely implanted to measure ACL and aortic PP, each received atrial-triggered ventricular pacing in 15 different randomized combinations of 3 pacing sites and 5 AV delays. Each trial contained 15 intrinsic beats (no pacing) and 5 paced beats; PP and ACL changes with pacing were averaged over. the 5 trials. The pacing combination with maximum ACL increase was hypothesized to be statistically related to maximum PP increase. For patients responding to pacing therapy (N = 20), the ACL algorithm predicted optimal or near-optimal (PP increase > 75% of optimal) pacing combinations for most of these patients (85%) and predicted combinations yielding 50-75% of optimal for the rest (15%). This paper describes an algorithm for optimizing PP response via transient ACL measurements. The ACL algorithm may allow rapid and minimally invasive optimization of pacing site and AV delay for CRT in CHF patients.