History of cigarette smoking and heart transplant outcomes

Background: Active cigarette smoking (CS) is a contraindication for Orthotopic Heart Transplantation (OHT) with a recommendation that HT candidates be free from CS for at minimum 6 months prior to HT. Animal studies have shown that a history of CS is associated with increased risk of allograft rejection, but few studies have examined the association of past CS and HT outcomes. Methods: Data were analyzed from HT recipients captured in the United Network for Organ Sharing (UNOS) transplant registry. Adults aged 18–79 who underwent HT from 1987 to 2018 and with data for all covariates (N = 32,260) were included in this study. The cohort was categorized by past smoking history (CS vs non-CS). Post-transplant outcomes of interest included survival, graft failure, treated rejection, malignancy and hospitalization for infection. Baseline characteristics were compared between the two groups using the chi-squared analysis. Unadjusted associations between CS and patient survival were determined using the Kaplan-Meier estimations and confounding was addressed using multivariable Cox proportional hazards models. Results: HT recipients with a history of CS were older (55 vs 50, p = <0.0001), more likely to be Caucasian (75.7 vs 62.3, p = <0.0001), male (81.7 vs 68.2, p =< 0.0001), and diabetic (27.4 vs 24.4, p =< 0.0001). CS was associated with significantly worse survival (HR: 1.23, p < 0.0001). A history of CS was also associated with increased risk of acute rejection (OR: 1.20, p < 0.0001), hospitalization for infection (OR:1.24, p < 0.0001), graft failure (OR:1.23, p < 0.0001) and post-transplant malignancy (OR:1.43, p < 0.0001). Conclusion: A history of CS is associated with increased risk of adverse events post OHT.