Air pollution may increase mortality risk after heart transplantation
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Air pollution may be associated with mortality in patients after undergoing a heart transplant, according to a study published in the Journal of the American College of Cardiology.
“We carried out this large analysis of heart transplant recipients in the United States and showed a linear relationship between ambient air pollution and mortality,” Sadeer G. Al-Kindi, MD, cardiologist at Harrington Heart and Vascular Institute at University Hospitals in Cleveland, told Healio. “This relationship appears qualitatively stronger that those seen in other less susceptible populations and raises the possibility of increased interaction between heart transplant status and air pollution. The relationship between air pollution and mortality continued despite adjustment for various recipient and donor characteristics.”
Heart transplant registry
Researchers analyzed data from 21,800 patients (mean age, 53 years; 75% men; 69% white; 39% ischemic etiology of HF) from the United Network for Organ Sharing/Organ Procurement and Transplantation Network who underwent heart transplantation between January 2004 and September 2015. Data were collected in the registry at the time of listing, during transplantation and regularly afterward and included clinical, demographics, hemodynamic and laboratory data, in addition to mortality, residential ZIP code, delisting reason, long-term outcomes and procedural outcomes.
The outcome of interest was defined as all-cause mortality. A ZIP code level, average annual particulate matter less than 2.5 mm in diameter (PM2.5) was the primary exposure of interest.
There were 86,713 patient-years of follow-up data collected during a median follow-up of 4.8 years. During follow-up, 23.9% of patients died. The mean annual exposure to PM2.5 during the study was 10.6 µg/m3.
The estimated mortality HR with each 10 µg/m3 increase in annual PM2.5 was 1.34 (95% CI, 1.21-1.49). After adjusting for donor, recipient and neighborhood variables, the estimated mortality HR was 1.26 with each 10 µg/m3 increase in annual PM2.5 (95% CI, 1.11-1.43).
The link between PM2.5 and mortality was consistent across subgroups including sex (P for interaction = .69), age (P = .85), bridging with mechanical circulatory support (P for interaction = .28), diabetes (P for interaction = .88), etiology (P for interaction = .94) and year of transplantation (P for interaction = .9).
“There are two main implications,” Al-Kindi said in an interview. “First, this study confirms prior observations about air pollution and mortality and expands it to this high-risk population. This will help shape policies that can drive air pollution levels down in the U.S. and globally. Second, there is growing evidence of the beneficial impact of air filtration on health parameters including immune activation. The current study will pave the way to test air filtration interventions in mitigating risk in heart transplant recipients.”
‘Remarkable’ excess risk
C. Arden Pope III, PhD, professor in the department of economics and Mary Lou Fulton Professor of Economics at Brigham Young University in Provo, Utah, and Aruni Bhatnagar, PhD, FAHA, professor of medicine, distinguished university scholar, Smith and Lucille Gibson Professor of Medicine, chief of the division of environmental medicine and director of the Christina Lee Brown Envirome Institute at University of Louisville in Kentucky, wrote an editorial about this study: “As the investigators point out, mortality in heart transplantation remains high, reaching 50% by 11 years. Given the large baseline mortality risk in cardiac transplant recipients, the relatively large excess mortality risk associated with PM2.5 air pollution is remarkable. These results may demonstrate the broader risks of chronic exposure to air pollution in diminishing health and further complicating those who already have chronic illness.” – by Darlene Dobkowski
For more information:
Sadeer G. Al- Kindi, MD, can be reached at sadeer.al-kindi@uhhospitals.org.
Disclosures: The authors of the study and the editorial report no relevant financial disclosures.
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