Resposta cronotrópica ao exercício após isolamento das veias pulmonares ou cirurgia de Cox-maze Chronotropic response to exercise after pulmonary veins isolation or Cox-maze operation

Objective: To evaluate the chronotropic response to exercise during immediate and late postoperative period after atrial fibrillation and mitral valve surgical treatment by different techniques. Methods: 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 crioablation (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. Results: 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 12 th 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). Conclusion: 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.