Measuring fractional flow reserve improves treatment of non-STEMI
MEASURING the myocardial fractional flow reserve (FFR) in patients with non-ST segment elevation MI (NSTEMI) avoided stents or surgery in more than one-fifth of patients, according to the FAMOUS-NSTEMI study presented in a Hot Line on Monday.
Coronary angiography in NSTEMI patients detects obstructive coronary artery disease and identifies patients who may benefit from coronary revascularisation. ‘Treatment decisions are based on subjective visual interpretation of the angiogram which may result in over or underestimation of the physiological significance of the lesion,’ explained investigator Colin Berry from Glasgow University, UK.
The FAMOUS-NSTEMI trial, funded by the British Heart Foundation, set out to explore whether management decisions in NSTEMI patients having coronary angiography guided by routine FFR measurements would be feasible, safe and provide additional clinical utility. The FFR technique uses a pressure sensitive coronary guidewire to assess the physiological significance of a coronary stenosis expressed as the ratio of maximal blood flow in a stenotic artery to maximal flow in an unobstructed artery. A fractional flow reserve value of 0.80 indicates that patients can be managed safely with medical therapy without the need for coronary revascularisation.
FAMOUS-NSTEMI, said Berry, differs from recent trials of FFR-guided management (DEFER, FAME, FAME-2) which enrolled patients with stable coronary artery disease.
Now, to be included in this study patients needed a diagnosis of acute NSTEMI, at least one risk factor for coronary artery disease (eg, diabetes mellitus), and to have either urgent invasive management planned within 72 hours of their heart attack, or a history of recurrent symptoms within five days.
The study took place between October 2011 and May 2013, and 350 subjects with a clinical diagnosis of recent NSTEMI were randomised to receive either treatment based on visual assessment of CAD (n=174) or a diagnostic FFR used to refine the treatment decision (n=176). Enrolment took place at six UK hospitals.
For the primary outcome the proportion of patients treated initially by medical therapy was 22.7 % in the FFR group and 13.2% in the angiography group (p=0.022). Information from the FFR procedure resulted in a treatment change between medical therapy, PCI or CABG in 21.6% of patients. The increased adoption of medical therapy at the expense of revascularisation in the FFR group was associated with similar overall health outcomes and quality of life at one year. ‘FFR is feasible and safe and avoids unnecessary stents and open-heart surgery,’ said Berry. A bigger study, he added, would definitively assess whether routine FFR-guided treatment would improve long-term survival and well being.