Short-Term Atrial Pacing and Hemodynamics After Cardiac Surgery

Cardiac surgery under cardiopulmonary bypass (CPB) frequently leads to immediate postoperative rhythm or conduction disturbances, especially atrial fibrillation or atrioventricular block (AV Block), along with hemodynamic instability and transient reduction in cardiac output due to myocardial contractility impairment. Temporary pacing wires are placed in the operating room and have been used since the 1960s to manage cardiac conduction disorders in these patients, allowing for atrial (AAI) or dual-chamber (DDD) pacing if necessary. Atrial pacing, by restoring synchronized atrial contraction with ventricular filling, helps maintain optimal cardiac output. Cardiac output is defined as the product of heart rate (HR) and stroke volume (SV). To optimize cardiac output, increasing heart rate is possible, hence the need for atrial pacing. A pacing rate slightly higher than spontaneous sinus rhythm appears to prevent pauses, limit rhythm instability, and reduce the risk of atrial fibrillation. However, the optimal pacing rate postoperatively has not been clearly defined, and data comparing different rates (70, 80, or 90 bpm) are scarce. In our center, postoperative atrial pacing is nearly routine and commonly set at 90 bpm, a rate we consider optimal due to its alignment with the Frank-Starling curve. This rate maximizes venous return and stroke volume, thereby optimizing postoperative cardiac output. Nevertheless, several studies have suggested that routine postoperative temporary pacing wire insertion may not always be necessary and should be reserved for patients identified as high-risk for postoperative rhythm disturbances. Nowadays, in many international centers, the absence of routine temporary pacing has become the norm. Although 90 bpm is theoretically the optimal rate for atrial pacing, important questions remain: Is postoperative pacing absolutely necessary? If so, could a rate lower than 90 bpm suffice to maintain adequate hemodynamic profile (HDP)? This study aims at determining whether routine temporary pacing is necessary during the first 24 hours after cardiac surgery under CPB, and what the optimal pacing rate is (AAI or DDD: 70 bpm vs. 80 bpm vs. 90 bpm) in terms of its impact on the HDP.