Phrenic nerve injury after coronary artery grafting: is it always benign?

Background: The purpose of this study was to evaluate the effect of phrenic nerve injury (PNI) occurring during coronary artery bypass grafting in patients with major chronic obstructive pulmonary disease (COPD).

Methods: Over a 42-month period, 1,303 patients underwent primary coronary artery bypass grafting. Sixty-seven (5.14%) had major COPD, and 29 (43.3%) of these 67 sustained PNI (group I). These patients were matched for age and ejection fraction with 29 CABG patients with COPD but without PNI (group II), 29 patients without COPD but with PNI (group III), and 29 patients with neither COPD nor PNI (group IV). The groups were compared on the basis of preoperative and operative factors and immediate and midterm morbidity and mortality.

Results: There were no significant differences between the groups with respect to hypertension, diabetes, ejection fraction, number of grafts, internal mammary artery use, cardiopulmonary bypass time, and ischemic time. Postoperatively, group I had a longer total hospitalization (group I, 11.7 days; group II, 7.8 days; group III, 7.8 days; and group IV, 6 days; p = 0.0001) and stay in the intensive care unit (I, 3.6 days; II, 2.2 days; III, 2.1 days; and IV, 1.2 days; p = 0.0023). More patients in group I required reintubation (I, 37.9%; II, 3.4%; III, 6.9%; and IV, 0%; p < 0.0001). Mean follow-up was 32.8 months (range, 7 to 48 months). Group I had more hospital readmissions (I, 78; II, 50; III, 61; and IV, 28; p < 0.007) and lower cumulative survival (I, 60.6%; II, 93%; III, 96.8%; and IV, 100%; p < 0.0015) compared with the other groups.

Conclusions: In patients with COPD, PNI during coronary artery bypass grafting has a major negative impact on immediate and midterm results.