A Randomized Crossover Study to Evaluate and Compare the Reproducibility and Tolerability of Direct Wire Pacing for Measuring Fractional Flow Reserve Versus Standard Method in Subjects With FFR Indications

Pressure wire-based Fractional Flow Reserve (FFR) has become the reference standard index of haemodynamic significance to guide revascularisation of intermediate coronary artery lesions.

The FFR measurement determines the ratio of the maximum blood flow that can be achieved in a diseased or narrowed coronary artery to the maximum blood flow in a normal coronary artery. This ratio represents the potential decrease in distal coronary flow relative to coronary stenosis.

FFR is easily measured during routine coronary angiography using a pressure wire to calculate the ratio of coronary pressure distal to a stenosis or diseased segment to aortic pressure under conditions of maximum myocardial hyperemia. An FFR of 1.0 is widely accepted as normal. An FFR of less than 0.80 is generally considered to be associated with coronary ischemia and widely accepted in favor of revascularization rather than conservative management.

The current standard method of measuring FFR is to insert a pressure wire into the coronary artery while the hyperaemic agent, usually adenosine, is delivered by intracoronary bolus or continuous intravenous injection.

Administration of adenosine may cause bradycardia and thus cause patient vagal discomfort. Direct Wire Pacing (DWP) can potentially overcome the drawbacks of the standard method when measuring FFR. Indeed, DWP allows to transmit an electrical current from the external pacemaker to the heart thanks to metallic FFR guidewire already used, and thus prevent bradycardia.