Clinical outcomes of automatic algorithms in cardiac resynchronization therapy: Systematic review and meta-analysis

Algorithms to automatically adjust atrioventricular (AV) and interventricular (VV) intervals in cardiac resynchronization therapy (CRT) devices are common, but their clinical efficacy is unknown.

The purpose of this study was to evaluate automatic CRT algorithms in patients with heart failure for the reduction of mortality, heart failure hospitalizations, and clinical improvement.

We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) in patients with CRT using automatic algorithms that change AV and VV intervals dynamically without manual input, on a beat-to-beat basis. We performed a subgroup analysis including intracardiac electrogram-based (EGM) algorithms and contractility-based algorithms.

Nine RCTs with 8531 participants were included, of whom 4275 (50.1%) were randomized to automatic algorithm. Seven of the 9 trials used EGM-based algorithms, and 2 used contractility sensors. There was no difference in all-cause mortality (10.3% vs 11.3%; odds ratio [OR] 0.90; 95% confidence interval [CI] 0.71-1.03; P = .13; I² = 0%) or heart failure hospitalizations (15.0% vs 16.1%; OR 0.924; 95% CI 0.81-1.04; P = .194; I² = 0%) between the automatic algorithm group and the control group. Study-defined clinical improvement was also not significantly different between groups (66.6% vs 63.3%; risk ratio 1.01; 95% CI 0.95-1.06; P = .82; I² = 50%). In the contractility-based subgroup, there was a trend toward greater clinical improvement with the use of the automatic algorithm (75% vs 68.3%; OR 1.45; 95% CI 0.97-2.18; P = .07; I² = 40%), which did not reach statistical significance. The overall risk of bias was low.

Automatic algorithms that change AV or VV intervals did not improve mortality, heart failure hospitalizations, or cardiovascular symptoms in patients with heart failure and CRT.