Researchers ID best techniques for cardiac risk stratification in kidney transplant candidates

Coronary artery calcium score (CACS) and coronary CT angiography (CTA) are the best predictors of all-cause mortality and major adverse cardiac events (MACE) in patients awaiting kidney transplantation, according to a new study in JACC: Cardiovascular Imaging.

Considering coronary artery disease is the leading cause of death among individuals on a kidney transplant waiting list, Danish researchers sought to analyze which cardiac imaging approaches demonstrated the best prognostic value in this patient population. In addition to CACS and coronary CTA, all 154 study participants underwent single-photon emission CT (SPECT) and invasive coronary angiography (ICA).

“Compared with traditional risk factors and other cardiac imaging modalities, CACS and coronary CTA seem superior for risk stratification in kidney transplant candidates,” wrote lead researcher Simon Winther, MD, with the department of cardiology at Aarhus University Hospital, and colleagues. “The use of a combination of risk factors and CACS and subsequent coronary CTA seems to be the most appropriate strategy for cardiac evaluation of renal transplant candidates.”

Of the 154 patients, 93.5 percent were white and 68.2 percent were men. The median follow-up time was 3.7 years, with a minimum follow-up of 2.8 years or until death.

The authors noted the ethnic uniformity of the study population was a limitation of their research.

Via candidate interviews and medical records, Winther et al. identified the following cardiovascular risk factors: smoking, high cholesterol, hypertension, established cardiovascular disease and left ventricular hypertrophy as diagnosed by echocardiography.

When grouped by CACS, scores of 0, 1 to 399 and 400 or above were associated with MACE rates of 2.0 percent, 3.1 percent and 10.1 percent per year. Yearly mortality rates were 3.3 percent, 3.8 percent and 9.4 percent for those groups.

The predictive power of CACS grew even stronger when cardiovascular risk factors were considered, according to Winther and colleagues.

“Combining risk factors and CACS in a prognostic model seems to improve risk prediction compared with using both risk factors or CACS alone,” they wrote. “This approach allowed for identification of 31% of the cohort as very-low-risk patients (less than three risk factors and CACS less than 400 with an event rate of MACE at 2.1 percent and mortality 1 percent per year) and the rest of the patients as high-risk patients (event rate of MACE at 6.2 percent and mortality 7.4 percent per year).”

Similarly, normal versus abnormal coronary CTA results helped the researchers identify half of the patients as low risk and half as high risk. Abnormal readings, which showed stenosis in a coronary artery segment, were associated with yearly rates of 7.6 percent for MACE and 7.1 percent for mortality. Patients with normal CTA results experienced yearly rates of MACE and all-cause death at 1.4 percent and 3.1 percent, respectively.

“Coronary CTA is a strong predictor of MACE and mortality and is superior to SPECT,” wrote the researchers, noting SPECT didn’t demonstrate significant prognostic power for either category.

Their findings also indicated ICA was a valid predictor of MACE but not mortality.