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App helps predict cardiovascular complications after liver transplant

Researchers developed a simple scoring model — accessible via web or smartphone apps — to assess the risk for cardiovascular disease after orthotopic liver transplantation, a transplant procedure with high cardiovascular risks.

Lisa B. VanWagner

“Knowing the patient’s risk is critical to help prevent the frequent cardiac complications that accompany liver transplant surgery and to determine which patients are likely to survive the transplant,” Lisa B. VanWagner, MD, assistant professor of medicine and preventive medicine at Northwestern University Feinberg School of Medicine and a Northwestern Medicine, said in a press release. “Identifying persons who are at highest risk may mean restricting transplantation so that we maximize the benefit of scarce donor organs to persons who have a lower risk of a cardiac event and are more likely to survive the stress of a liver transplant.”

To determine potential risk factors or markers for major cardiovascular complication within 1 year after orthotopic liver transplantation, the researchers gathered data from 1,024 patients who underwent initial liver transplant between Feb. 1, 2002, and Dec. 31, 2011, with follow-up data through Dec. 31, 2012.

There were 498 cardiovascular complications among 329 patients within 1-year posttransplant, 75.1% of which occurred in the early perioperative period. Complications included heart failure (n = 154), atrial fibrillation (n = 130), stroke or transient ischemic attack (n = 90) and myocardial infarction (n = 60). Of the 120 deaths in the first year posttransplant, 17 were related to cardiovascular complications.

The significant CVD-related risks after adjustment included not working for income status (RR = 1.7; 95% CI, 1.28-2.11), high school education or lower (RR = 1.31; 95% CI, 1.07-1.58), positive history of atrial fibrillation (RR = 2.52; 95% CI, 1.98-2.84), hypertension (RR = 1.27; 95% CI, 1.02-1.53), pulmonary hypertension (RR = 1.62; 95% CI, 1.22-1.96) and diabetes (RR = 1.26; 95% CI, 1.01-1.52), negative history of hepatocellular carcinoma (RR = 1.42; 95% CI, 1.17-1.67), and current respiratory failure on ventilator at transplant (RR = 1.88; 95% CI, 1.47-2.23).

Additionally, the risk for cardiovascular disease became significant at 55 to 59 years old (RR = 1.15; 95% CI, 0.75-1.63) and increased with age. Other significant factors included African-American ethnicity (RR = 1.7; 95% CI, 1.28-2.11) and Caucasian ethnicity (RR = 1.48; 95% CI, 1.11-1.84). There was a minor factor for female sex (RR = 1.06; 95% CI, 0.84-1.31).

Based upon the significance of each factor, the researchers assigned points related to predictive risk to develop the CAR-OLT score. Points on the CAR-OLT score reflect a 1-year absolute predicted risk percentage. Below nine points represents a less than 5% risk, while above 40 points represents a 45% or higher risk.

In this study, 691 patients had a CAR-OLT score below 40, indicating a predicted probability of developing cardiovascular complications within 1-year of less than 40%. This was compared with 30.1% of patients with scores above 40 points, who had more than a 45% predicted risk. The predicted number of cardiovascular complications generally matched the study outcomes.

The model demonstrated good discrimination (C statistic = 0.78) and calibration (Hosmer-Lemeshow, P = .33).

“Whether use of the CAR-OLT score for risk stratification and the decision to proceed with more intensive cardiovascular testing or targeted risk factor reduction would be helpful to improve CVD outcomes after OLT requires external validation in a future multicenter clinical trial,” the researchers concluded.

The app can be accessed at http://carolt.us or via iTunes and Google Play. – by Talitha Bennett

Disclosure: Van Wagner reports she is on the speakers bureau for Valeant and received grants from Novartis. Please see the full study for the other researchers’ relevant financial disclosures.