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Primary endpoints of the biventricular pacing after cardiac surgery trial
Henry M Spotnitz1, Santos E Cabreriza, Daniel Y Wang
1Department of Surgery, Columbia Presbyterian Medical Center, New York, New York 10032, USA. hms2@columbia.edu
Insights
Optimized biventricular pacing did not significantly increase overall cardiac index but showed a 29% improvement in aortic valve surgery patients. Mean arterial pressure also increased with pacing, suggesting potential benefits in specific cardiac surgery populations.
Area of Science:
- Cardiology
- Cardiac Surgery
- Biomedical Engineering
Background:
- Patients undergoing cardiopulmonary bypass for cardiac surgery are at risk of left ventricular dysfunction.
- Optimized biventricular pacing is being investigated as a method to improve cardiac output in these patients.
- This study focused on patients undergoing coronary artery bypass, aortic, or mitral valve surgery.
Purpose of the Study:
- To determine if optimized biventricular pacing enhances cardiac index in patients at risk of left ventricular dysfunction post-cardiopulmonary bypass.
- To evaluate the impact of pacing optimization on cardiac index and mean arterial pressure.
- To explore potential benefits in specific surgical subgroups.
Main Methods:
- 61 patients were randomized into pacing or control groups after screening 6,346 patients.
- Atrioventricular and interventricular delays were optimized at three time points post-bypass.
- Cardiac index was measured using thermal dilution, and statistical analysis included t-tests and linear mixed effects models.
Main Results:
- Overall cardiac index showed a non-significant 12% increase in the paced group (p=0.14).
- A significant 29% increase in cardiac index was observed in the combined aortic and aortic-mitral surgery groups (p=0.0138).
- Mean arterial pressure significantly increased with pacing across all optimization phases (p<0.01).
Conclusions:
- Optimized biventricular pacing did not significantly improve overall cardiac index but demonstrated a notable increase in specific aortic surgery patient groups.
- Pacing led to a significant increase in mean arterial pressure.
- Further research is recommended to differentiate pacing effects and assess clinical outcomes.
Background:
This study sought to determine whether optimized biventricular pacing increases cardiac index in patients at risk of left ventricular dysfunction after cardiopulmonary bypass. Procedures included coronary artery bypass, aortic or mitral surgery and combinations. This trial was approved by the Columbia University Institutional Review Board and was conducted under an Investigational Device Exemption.
Methods:
Screening of 6,346 patients yielded 47 endpoints. With informed consent, 61 patients were randomized to pacing or control groups. Atrioventricular and interventricular delays were optimized 1 (phase I), 2 (phase II), and 12 to 24 hours (phase III) after bypass in all patients. Cardiac index was measured by thermal dilution in triplicate. A 2-sample t test assessed differences between groups and subgroups.
Results:
Cardiac index was 12% higher (2.83±0.16 [standard error of the mean] vs 2.52±0.13 liters/minute/square meter) in the paced group, less than predicted and not statistically significant (p=0.14). However, when aortic and aortic-mitral surgery groups were combined, cardiac index increased 29% in the paced group (2.90±0.19, n=14) versus controls (2.24±0.15, n=11) (p=0.0138). Using a linear mixed effects model, t-test revealed that mean arterial pressure increased with pacing versus no pacing at all optimization points (phase I 79.2±1.7 vs 74.5±1.6 mm Hg, p=0.008; phase II 75.9±1.5 vs 73.6±1.8, p=0.006; phase III 81.9±2.8 vs 79.5±2.7, p=0.002).
Conclusions:
Cardiac index did not increase significantly overall but increased 29% after aortic valve surgery. Mean arterial pressure increased with pacing at 3 time points. Additional studies are needed to distinguish rate from resynchronization effects, emphasize atrioventricular delay optimization, and examine clinical benefits of temporary postoperative pacing.
