Diaphragm Dysfunction after Coronary Artery Bypass Grafting is Associated with Increased Postoperative Morbidity

Objective We sought to describe the incidence, postoperative outcomes, and rate of recovery in CABG patients who develop postoperative diaphragm dysfunction (DD). Methods We retrospectively reviewed patients undergoing isolated CABG at our institution between July 2015 and May 2025. Diagnosis of DD was based on diaphragmatic elevation on routine postoperative chest X-ray and was confirmed by sniff test. Postoperative outcomes were compared between patients with and without DD using inverse probability of treatment weighting (IPTW). Results The incidence of postoperative DD after CABG was 3.1% (111/3594), with 60 left-sided DD, 50 right-sided DD, and 1 patient with bilateral DD. Preoperative characteristics were similar between those with and without DD. Only seven patients developed DD without ipsilateral IMA harvest; all seven were right-sided DD after isolated LIMA harvest (0.3%, 7/2084). After IPTW weighting, patients with DD had longer lengths of stay (8 vs 7 days; p=0.01), as well as increased rates of postoperative pneumonia (5.7% vs 2.3%, p=0.02), reintubation (7.4% vs 2.1%, p=0.001), ICU readmission (5.0% vs 1.9%, p=0.04), and cardiac arrest (3.8% vs 1.1%, p=0.03). Early mortality was similar between groups (p=0.52). Of patients with left DD, 45% (27/49) demonstrated recovery at a median of 7.5 months (IQR 3.1-18.9), while 50% (19/38) of patients with right DD demonstrated recovery at a median of 3.6 months (IQR 3.1-33). Conclusions While the overall rate of diaphragm dysfunction after CABG surgery is low, it is associated with increased postoperative morbidity. Further investigations into DD after CABG are necessary.