Angio-based Fractional Flow Reserve to Predict Adverse Events After Stent Implantation

Fractional flow reserve (FFR) allows to evaluate the functional significance of coronary artery lesions, through the ratio of the mean coronary artery pressure after the stenosis to the mean aortic pressure during maximum hyperaemia. The actual widely accepted cutoff value is 0.80. Below this value, an intermediate coronary lesion is considered significant and its treatment with percutaneous coronary intervention (PCI) is justified.

The measurement FFR after stent implantation has a strong predictive value with respect to death, myocardial infarction, or need for repeat revascularization of the target vessel within 6 months. The higher the FFR, the lower the event rate. FFR cut-off of 0.90 might be a useful indicator in daily practice for optimal physiologic stent implantation. Nevertheless, the use of the FFR in the post stenting , is relatively low, because of costs of the pressure wire and the adverse effects related to the use of adenosine.

A new method (QFR by Medis medical imaging) for evaluation of the functional significance of coronary stenosis is based on computer calculation of the FFR value. This calculation is performed by analysing the coronary angiogram and thus reduces or potentially eliminates the need for measuring FFR by pressure wires. The QFR method combines a 3D reconstructions of the target vessel based on two angiographic projections and the contrast flow velocity to compute the "FFR value". To perform QFR the investigators will acquire two angiographic projections with angle >25 degree that allow the 3D reconstruction of the vessel (see values below).

Projections for left main (LM) and proximal left anterior descending (LAD) or proximal left circumflex (LCX): right anterior oblique (RAO) 20, Caudal 45 and anterior-posterior (AP), Caudal 10

Projections for LAD/diagonal: AP, Cranial 45 and RAO 35, Cranial 20

Projections for LCX/obtuse marginal (OM): left anterior oblique (LAO) 10, Caudal 45 and RAO 25, Caudal 25

Projections for Proximal+Mid right coronary artery (RCA): LAO 45, caudal (CAUD) 0 and AP, CAUD 0

Projections for postero-lateral artery and posterior-descending artery (PLA/PDA): LAO 45, CAUD 0 and LAO 30, CAUD 30

Finally, the investigators will assess the relationship between QFR value and adverse events. We will assess the best QFR value able to discriminate the cumulative occurrence of adverse events. In the study, we will include also ST-segment elevation myocardial infarction patients. This subset of patients will be analysed as independent cohort to obtain preliminary results and will be analysed in a independent study

Inclusion criteria

-successfull percutaneous coronary intervention and stent implantation

Exclusion criteria

• inability to provide consent
• inability to guarantee at least 1-year follow-up
• thrombolysis in myocardial infarction (TIMI) flow <3
• life expectancy <1 year
• previous coronary artery bypass graft
• atrial fibrillation
• ongoing ventricular arrhythmias
• significant and persistent tachycardia (heart rate >100 bpm)