Chronotropic response to exercise after pulmonary veins isolation or Cox-maze operation

To evaluate the chronotropic response to exercise during immediate and late postoperative period after atrial fibrillation and mitral valve surgical treatment by different techniques.

Prospective controlled clinical study of 42 patients presenting chronic AF associated mitral valve disease, who underwent surgery by the techniques of pulmonary veins isolation (n=16), Modified Cox-maze procedure, without cryoablation (n=13), both with isolated mitral valve repair (n=13). The preoperative clinical characteristics, surgical indications, kind and aetiology of valve lesion were similar between groups. The patients were outpatient followed-up and underwent series of ergometric tests.

In the immediate postoperative period, chronotropic response was similar in the 3 groups with mean of 73.6 +/- 12.3% of maximal calculated heart rate. In the surgical pulmonary veins isolation group, there was an increment of heart rate, from 64.4 +/- 12.4% of maximal heart rate in the immediate postoperative period to 78.9 +/- 10.5% in the 12th month (P=0.012) of postoperative. In the Cox-maze group, heart rate varied, respectively, from 73.9 +/- 11.14% to 78.8 +/- 15.2% (P=1.000) and in the control group (only mitral valve surgery), from 67.2 +/- 14.3% to 71.9 +/- 12.9% (P=0.889).

An attenuation of immediate postoperative chronotropic response to exercise was similar in the postoperative in the three different surgical techniques. There was a significant improvement in this response concerning to postoperative outcome in the pulmonary veins isolation group. These results suggest that simple surgical pulmonary veins isolation may be related to a better preservation of atrial chronotropism.