During a seven year follow-up study, researchers found that people with mild chronic kidney disease (CKD) face double the risk of death from all causes after angioplasty or bypass surgery, and triple the risk of death from cardiovascular disease, compared to those without CKD. “Our data suggests that mild CKD should raise a red flag for doctors to monitor patients more closely for heart disease,” says lead author Lynda Anne Szczech, M.D., M.S.C.E., an assistant professor of medicine at Duke University Medical Center in Durham, N.C.
This is the first randomized trial to examine the effects of CKD on the outcomes of angioplasty and coronary artery bypass surgery, says Szczech. “We found that even a small decrease in kidney function increases the risk for post-procedure complications, recurrent hospitalizations and repeat angioplasty within seven years of the initial procedure.” One manifestation of kidney disease is end-stage renal disease (ESRD), which affects more than 300,000 people in the United States and requires blood-cleansing treatment on a dialysis machine. Many people with ESRD die of cardiovascular causes.
“We know the risk of cardiovascular disease begins well before ESRD, during the period of CKD,” she says. Mild CKD can have few symptoms—sometimes showing up only as blood tests for kidney function that fall out of the usual range. The condition is expected to become more common due to increasing rates of diabetes in this country and an aging population. The 3,608 patients in the study were part of a larger trial called the Bypass Angioplasty Revascularization Investigation (BARI), which randomly assigned patients to angioplasty or bypass surgery. In angioplasty, a balloon is threaded into an artery and inflated to open up areas blocked by atherosclerosis, the buildup of fats and cellular debris. Bypass surgery uses a blood vessel taken from the chest or leg to route blood around severe blockages in the coronary arteries. The subjects included 76 with CKD, 30 of whom also had diabetes.
All-cause mortality for those with both mild CKD and diabetes was 70 percent, she adds. “The presence of both conditions is worse than the sum of their parts. I don’t know why they are synergistic,” she says. “Perhaps it is that while renal dysfunction is a strike against a person in and of itself, when it is caused by a multi-organ disease such as diabetes, it not only contributes to its risk but acts as a marker for the amount of damage done to organs other than the kidney.”
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