TORONTO—Coronary artery disease (CAD) is associated with a significantly increased risk of death among people with chronic renal failure. Moreover, the prognosis is not completely benign when renal failure patients have non-obstructive CAD, a large international study has shown.
Investigators performed coronary computed tomography angiography (CCTA) on more than 5,000 patients and found those with either non-obstructive or obstructive CAD had a significantly shorter average survival than patients without CAD. Every 10-unit decrease in estimated glomerular filtration rate (eGFR) was associated with a 23% increased risk of death.
The researchers, who presented the results in poster form at the 2012 Canadian Cardiovascular Congress, are urging nephrologists to consult with a cardiologist or radiologist regarding patients at risk for atherosclerosis.
“The take-home message from this [study] is that cardiac CT can be used to detect CAD and cardiac risk stratification in chronic renal failure patients,” said the study’s first author, Girish Dwivedi, MD, PhD, a cardiac-imaging fellow at the Ottawa Heart Institute. “Cardiac CT can be safely performed in patients with moderate renal failure and also in severe renal failure if the latter are on hemodialysis.” Dr. Dwivedi advised that only the lowest possible contrast dose should be used for the imaging study in such patients. Patients should be kept well-hydrated and that nephrotoxic drugs such as metformin should be stopped before the CCTA and should be re-introduced usually 48 hrs after the test when the renal function returns to the pre-test level.
This is one of the many analyses of data from the CONFIRM (COroNary Computed Tomography Angiography Evaluation for Clinical Outcomes: An InteRnational Multicenter Registry) study, which was led by Benjamin Chow, MD, of the University of Ottawa Heart Institute. Researchers from six countries, including the United States, Canada and Europe, screened 27,125 consecutive patients undergoing CCTA from February 2003 and December 2009. The present study included only those patients who had serum creatinine, and left ventricular ejection fraction (LVEF) assessments, as well as those for whom follow-up data were available. The researchers excluded those with a history of coronary revascularization, congenital heart disease, or cardiac transplantation.
A total of 5,572 patients were included in the study. Their mean age was 55.4 years, 52% were men, and the average follow-up time was 18.6 months. Sixty-six died.
Patients’ survival was significantly shorter compared with those who had no CAD when they had either non-obstructive or obstructive CAD. Dr. Dwivedi’s group confirmed that the cardiac CT provides incremental information over and above the other well established clinical variables for the mortality prediction in such patients. When they controlled for confounding factors they found that impaired renal function was associated with a 2.3-fold increased mortality risk. CAD severity and LVEF less than 50% were also highly significantly associated with mortality.
Although the use of only clinical variables with eGFR and CAD severity was associated with a much more accurate prediction of survival than clinical variables alone, overall the most accurate prediction of mortality was obtained by the combination of clinical variables, eGFR, CAD severity, and abnormal LVEF data.