EXPERT ANALYSIS AT THE CARDIOVASCULAR CONFERENCE AT SNOWMASS
SNOWMASS, COLO. (FRONTLINE MEDICAL NEWS) – Coronary artery bypass graft surgery in patients with severe ischemic left ventricular dysfunction is overdue for an upgrade in status in the American College of Cardiology/American Heart Association guidelines on the strength of the landmark STICH trial and its extended follow-up stage known as STICHES, according to Vinod H. Thourani, MD.
Currently, the guidelines give CABG in this large and growing population a class IIb recommendation, meaning it “might be considered.” This undervalues the study’s core lesson: “STICHES showed a clear survival benefit with CABG, so this most likely should become a class IIa recommendation,” Dr. Thourani said at the Annual Cardiovascular Conference at Snowmass.
He went on to describe how he applies the key study findings to individual patients.
STICH (Surgical Treatment for Ischemic Heart Failure) was a National Institutes of Health–sponsored 22-nation trial involving 1,212 patients with a left ventricular ejection fraction of 35% or less, no or minimal angina, a mean age of 60 years, and coronary artery disease amenable to CABG. The patients were randomized to CABG plus optimal medical therapy or optimal medical therapy alone and followed via STICHES for a median of 9.8 years.
At 5 and 10 years of follow-up, the probability of all-cause mortality was reduced by 14% and 16%, respectively, in the CABG group. The surgery provided on average an 18-month extension of life. The price paid for the CABG benefit was a 3.6% mortality rate at 30 days; however, this was overcome by the 2-year mark, at which point survival in the CABG group surpassed that in controls. Thereafter, the all-cause mortality gap between the two groups continued to widen for the duration of follow-up.
For the composite endpoint of all-cause mortality or cardiovascular hospitalization, the CABG group enjoyed a 26% relative risk reduction, compared with optimal medical management alone at 5 years, and a 28% reduction in risk at 10 years. The two study groups diverged in terms of risk of cardiovascular hospitalization after only 3 months.
CABG provided a reduction in the risk of cardiovascular death that was consistent across all ages. In contrast, the reduction in all-cause mortality was not, since a higher proportion of deaths in older patients came from cancer and other noncardiovascular causes ( Circulation. 2016 Nov 1;134[18]:1314-24 ).
There have been no randomized, controlled trials of percutaneous coronary intervention in patients with heart failure.
“An interesting finding in STICHES was that medical therapy had a much higher 10-year all-cause mortality the younger the patient was. So CABG particularly benefits those who are at a younger age – in this study, age 60 or less. As you get older, say, at 80 years of age, I’m not sure there’s a huge benefit in all-cause mortality at that point,” said Dr. Thourani, professor of surgery and medicine, and codirector of the structural heart and valve center at Emory University in Atlanta.
In a STICH substudy, roughly half of participants underwent presurgical myocardial viability testing via single-photon emission CT and/or dobutamine echocardiography. The investigators found that the results didn’t predict mortality benefit for CABG ( N Engl J Med. 2011 Apr 28;364[17]:1617-25 ).
More recently, however, other investigators have reported MRI to have prognostic value. For example, Belgian investigators showed that medical therapy in patients with ischemic heart failure and dysfunctional but viable myocardium on delayed-enhanced MRI was associated with a 4.56-fold increased likelihood of mortality during 3 years of follow-up, compared with complete revascularization via CABG ( J Am Coll Cardiol. 2012 Feb 28;59[9]:825-35 ).
“This observation has been useful for me,” Dr. Thourani said. “My own personal practice is if I have good targets, I don’t do viability testing, but if I have really bad targets where I know I’m going to have a tough time sewing grafts, I try to get an MRI for viability testing.”
One important lesson of STICH is that all patients with heart failure and a low left ventricular ejection fraction should have a coronary angiogram, even if they are free of ischemia on noninvasive testing and have no angina. That’s because the patients enrolled in STICH had little or no angina, the surgeon continued.
These STICH-type patients will benefit greatly from a heart team assessment factoring in an individual’s Society of Thoracic Surgeons’ predicted risk score, based on age, comorbidities, and other factors. For example, if a patient’s STS risk score with CABG is 0.7%, that’s a strong argument for opting for the surgery, since the 30-day operative mortality in STICH was 3.6%. If, on the other hand, the STS score is greater than 7%, that’s a tougher call.
“I think it’s really important that a heart team assessment includes a noninvasive cardiologist as well as an interventional cardiologist and cardiac surgeon because I think interventionalists and cardiac surgeons sometimes get a little goofy in their assessment of these patients,” Dr. Thourani said.
Patients with a low ejection fraction and coronary artery disease who are deemed poor candidates for CABG should be evaluated for a mechanical circulatory support device or a heart transplant.
“I think that’s something we don’t think about enough, quite honestly,” he said.
Dr. Thourani reported serving as a consultant to Abbott Vascular, Edwards Lifesciences, and Gore, and receiving research grants from numerous companies.
