Coronary artery bypass graft (CABG) surgery guided by fractional flow reserve (FFR) significantly reduced the incidence of death or myocardial infarction when compared to angiography-guided CABG, according to an observational study with an average follow-up of seven years.
“We previously reported that FFR-guided coronary artery bypass grafting was associated with simplified surgical intervention (ie, lower number of graft anastomoses and lower rate of on-pump surgery) and higher graft patency rate at three years as compared with angiography-guided CABG,” lead author Stephane Fournier, MD, and colleagues wrote in Circulation: Cardiovascular Interventions. “Beyond the lower rate of angina Canadian Class Society II–IV, no significant benefit was observed in terms of clinical events reduction in the FFR-guided CABG patients. However, clinical manifestations of graft failure might be time-dependent.”
To investigate outcomes over a longer period of time, Fournier and colleagues propensity-matched 198 patients who underwent FFR-guided CABG with the same number who had stenoses grafted based on angiography. Patients were evenly matched by age, sex and diabetes status.
Over a median follow-up of 87 months, FFR guidance was independently associated with a 49 percent mortality reduction upon multivariable analysis. The rate of overall death or myocardial infarction was 16 percent in the FFR group and 25 percent in the angiography group.
Major adverse cardiovascular events—a composite of death, MI and target vessel revascularization—occurred in 21 percent of FFR-guided patients and 26 percent of those who were assessed via angiography.
“Our findings indicate for the first time that a significant reduction in death or MI is associated with surgical myocardial revascularization guided by FFR as compared with traditional angiographic guidance,” the authors wrote. “Importantly, this clinical benefit does not come at the cost of excess in recurrent revascularization.”
Patients were included in the single-center study if they had at least one stenosis with a diameter between 50 and 70 percent upon visual examination. FFR measures of 0.80 or less prompted revascularization, while grafting was deferred if FFR was above 0.80.
“A linear increase in the rate of death or MI with increasing number of venous grafts was observed when using angiography, but not in the FFR-guided group,” Fournier et al. wrote. “The latter finding supports the concept that FFR-guidance, either by reducing the number of venous grafts per patient or by selectively targeting functionally stenotic native coronary arteries, might limit the potential untoward impact derived from degeneration of these less desirable vascular conduits.”
The researchers noted their analysis is limited by its observational, retrospective design, which leaves open the possibility for selection bias and residual confounding. They also didn’t track outcomes by surgeon even though different operators may have had varying levels of experience and expertise.
In a related editorial, two researchers from the University of California, Irvine, said the study “is in concert with the large body of work supporting the application of physiologically-guided revascularization.” They pointed out several studies have refuted the notion that even mild lesions should be bypassed, and FFR can determine the severity of stenosis more accurately than visual assessment.
“Critically important to accepting then changing CABG practice is the reality that interventional cardiologists must also accept it and help their surgical colleagues appreciate the value of ischemia-directed revascularization,” wrote Morton J. Kern, MD, and Arnold Seto, MD. “New technologies such as FFR-computed tomography or angiographically-derived FFR will likely make this task considerably easier than an invasive pressure wire measurement.”