Their value immediately after surgery is being questioned.
Drugs known as angiotensin-converting enzyme (ACE) inhibitors can make all the difference in the world to length and quality of life for some people with heart disease and high blood pressure, one of the risk factors for heart disease. ACE inhibitors work by blocking hormones that regulate blood vessel constriction. This can reduce damage to the heart and kidneys in many ways—for example, by slowing deterioration of the heart muscle that occurs over time following a heart attack or deterioration of the kidneys in people with diabetes and kidney disease. The first ACE inhibitor, captopril (Capoten), was approved by the FDA in 1981 to lower blood pressure. Nine more are available today (see box).
In the early 1990s, the ability of ACE inhibitors to prolong survival in people with heart failure was discovered, along with their ability to lower the risk of having a heart attack. Soon thereafter, Harvard researchers led by Dr. Marc Pfeffer found that people taking ACE inhibitors were less likely to die from their heart attacks. These unique benefits secured the place of ACE inhibitors mong the most significant drugs for the treatment of heart disease.
Value in CABG unclear
But for people undergoing coronary artery bypass grafting (CABG)—a highly stressful time for the heart—the benefits of ACE inhibitors remain controversial.
In 2007, Canadian physicians found that starting an ACE inhibitor within seven days after CABG made no difference in the rate of cardiovascular death, nonfatal heart attack, need for another procedure to open blood vessels, angina, hospitalization for heart failure, or stroke.
Last year, researchers in the United States and Israel decided to see what happens when ACE inhibitor therapy is discontinued after CABG. They examined 4,224 people for whom ACE inhibitors were stopped, continued, added, or never given. They found that continuing treatment with an ACE inhibitor, or adding an ACE inhibitor for the first time after CABG, substantially reduced the risk of dying in the hospital or suffering a heart attack, heart failure, stroke, or kidney failure. This directly contradicted the Canadian findings. On the other hand, stopping ACE inhibitor therapy after CABG increased the risk for these events.
What does this mean for people about to undergo CABG? Dr. Pfeffer is not convinced that this study proved that starting an ACE inhibitor is beneficial or that stopping one is harmful in the period immediately following CABG. “It is not possible to ascertain the reasons why some patients were continued on ACE inhibitors and others were taken off their medication. There could be some important reasons that influenced the outcomes,” he says.
“I want to emphasize that the benefits of ACE inhibition are the results of long-term treatment, especially for those with impaired heart function. During cardiac surgery, your caregivers will reassess the more short-term benefits versus risks of continuing this important therapy.”