Bypass surgery results in better five-year survival than balloon angioplasty and
stent procedures for patients with serious
coronary artery disease and additional health conditions such as
diabetes, according to a study published in today’s rapid access issue of
Circulation: Journal of the American Heart Association.
In a group of patients with multiple clogged coronary arteries and other high-risk characteristics, death rates after five years for those who underwent coronary artery bypass grafting (CABG) were almost half the rate of patients who received percutaneous coronary intervention (PCI). PCI involves angioplasty or stenting to widen a narrowed blood vessel in the heart.
“The sicker the patient the more bypass surgery helped,” said study author Sorin J. Brener, M.D., assistant professor of medicine and medical director of the Angiography Core Laboratory at the Cleveland Clinic Foundation in Ohio. “The findings were somewhat surprising. Even in this era of advanced PCI with stents and glycoprotein IIb/IIIa antiplatelet therapy, bypass surgery saved more lives.”
Glycoprotein (GP) IIb/IIIa inhibitors are antiplatelet drugs administered intravenously to reduce blood clotting.
This is one of the largest studies to compare five-year survival rates in groups of bypass and contemporary PCI patients, most of whom received stents and GP IIb/IIIa inhibitors. The survival advantage was evident even though patients in the CABG group had considerably higher overall health risks. The advantage was even greater among those with diabetes and advanced heart failure.
Brener and his colleagues examined survival records for 5,161 patients who underwent bypass surgery and 872 who had PCI at Cleveland Clinic. Roughly one-half of patients in both groups had diabetes or significant left ventricular dysfunction. While overall survival rates were similar between the two groups, significant differences emerged as the researchers used propensity analysis, a process whereby individual patient cardiovascular risk characteristics – hypertension, smoking, diabetes and other factors – as well as many other procedural elements are factored into the comparison matrix.
“Mortality rates for patients who underwent surgical bypass were almost half the rate of those treated with angioplasty who had similar cardiovascular risk profiles,” said Brener. The one- and five-year unadjusted mortality rates were 5 and 16 percent for PCI, and 4 and 14 percent for CABG. However after propensity analysis adjustment, PCI was associated with a significantly higher death rate across all categories, including patients with left ventricular dysfunction and diabetes. One of the likely explanations is that bypass grafts helped prevent damage from subsequent artery blockages, he said.
Because patients who undergo bypass surgery at the Cleveland Clinic have mortality rates that are one-third the national average during the initial hospital stay, the results may not as be good in other hospitals, cautioned Brener.