Impact of the Cox-Maze IV Procedure on Left Atrial Mechanical Function

The Cox-Maze IV procedure is a proven surgical treatment for atrial fibrillation (AF). Previous studies on the procedure and its effect on left atrial mechanical function have yielded mixed results.

Sixty-four (64) patients underwent Cox-Maze IV at St Vincent's Hospital, Melbourne between March 2010 and May 2016. Baseline characteristics were collected and outcomes assessed including rhythm analysis. Preoperative and postoperative transthoracic echocardiograms were reviewed.

Fifty-seven (57) patients had complete follow-up with all clinical measures collected. The mean age was 71.1±10.2years, 63% being male. Fifty-eight per cent (58%) (33/57) of patients were in AF and 42% (24/57) in sinus rhythm (SR) at preoperative transthoracic echocardiography. Follow-up postoperative transthoracic echocardiography was performed at a mean of 2.3±1.9years. Nineteen (19) patients with a history of paroxysmal AF were in SR both preoperatively and postoperatively. In these patients, there was a significant decrease in Mitral A wave 0.63±0.28m/s (pre-op) vs 0.47±0.29m/s (post-op), p=0.044. There was a significant decrease in left ventricular ejection fraction (LVEF) postoperatively 64.2±9.7% vs 55.0±12.9%, p=0.005. At follow-up, 28% (16/57) were in AF, 61% (35/57) in SR, and 11% (6/57) in a paced rhythm. In a multivariate analysis, predictors of AF recurrence included higher LA volumes (p=0.042) and younger age at surgery p=0.030. Preoperative AF, sex and LVEF had no impact on AF recurrence.

The Cox-Maze IV procedure, while effective in converting patients to sinus rhythm, may reduce left atrial mechanical function in patients with paroxysmal AF.