Pre-operative Pulmonary Function Tests and Outcomes After Heart Transplantation

Abstract

The pulmonary function test (PFT) is a component of the evaluation for heart transplantation. Though data on the relationship between lung disease and post-transplantation outcomes are lacking, PFTs play a role in patient selection for transplantation. We aimed to characterize pulmonary disease in heart transplant recipients and to assess the impact of diminished lung function on post-operative outcomes. We studied a cohort of 136 patients who received a heart transplant at our institution between 2004 and 2014. Pre-operative PFTs, including forced expiratory volume in one second (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, and total lung capacity (TLC), were documented. The incidence and severity of obstructive, restrictive, and mixed obstructive-restrictive lung disease were evaluated. Primary endpoints were post-transplantation hospital length of stay (LOS), intensive care unit (ICU) LOS, and days on ventilator. Secondary endpoint was mortality one year after transplant. Unadjusted and adjusted logistic and Poisson regression analyses were conducted to determine the association between measures of lung function and post-operative outcomes. Our heart transplant recipients, consisting primarily of males (82%) and Caucasians (88%), were on average 58±12 years old. At baseline, the mean body mass index (BMI) was 27±4 kg/m2 with 59% who were prior smokers and 39% who had previously received non-transplant cardiac surgery. Mean exercise oxygen consumption at baseline was 10.1±2.8 ml/min/kg. There were 12 (10%) patients with obstructive lung disease and 57 (50%) with restrictive disease. An additional 19 (17%) had mixed obstructive-restrictive lung disease. In the restrictive and mixed groups, severe-to-very severe disease was present in 7 (12%) and 2 (11%) patients, respectively. The median post-transplantation hospital LOS was 24 days (mean: 41±53), while the median post-transplantation ICU LOS was 5 days (mean: 17±44). Patients were intubated after transplant for a median duration of 3 days (mean: 8±17). There were 15 (11%) patients who experienced 1-year post-operative mortality. After adjustment for potential confounders such as age, smoking, and BMI, decreasing FEV1 and FEV1% predicted were significantly associated with increasing post-transplantation hospital LOS, ICU LOS, and ventilator days (p<0.05). Similarly, as FVC and FVC% predicted decreased, significantly higher post-transplantation hospital LOS, ICU LOS, and ventilator days were observed (p<0.05). Declining TLC and TLC% predicted were also associated with significantly rising post-transplantation hospital LOS, ICU LOS, and ventilator days (p<0.05). No relationship was found between PFTs and mortality. Pulmonary disease is common in heart transplant recipients with restrictive lung disease being more prevalent in our cohort. Reduction in lung function is significantly associated with increased post-transplantation hospital LOS, ICU LOS, and ventilator days.