Fractional Flow Reserve as Evidence of Improvement in Coronary Flow After Subclavian Artery Stenting to Grafted Left Anterior Descending Artery
A 56-year-old man was admitted for the short term with a non-ST elevation myocardial infarction. His background history included coronary artery bypass graft surgery 7 years previously when he had received a left internal mammary artery graft to the left anterior descending artery, and saphenous vein grafts to his first diagonal and right coronary arteries. In recent years, he had been complaining of exertional angina.
Coronary angiography demonstrated native left main-stem stenosis and proximal left anterior descending artery disease (Figure 1). Only the saphenous vein graft to the first diagonal was patent. It was difficult to intubate the left internal mammary artery, and a subsequent subclavian artery injection revealed a severe stenosis proximal to the left internal mammary artery, with poor flow down the internal mammary conduit (Figure 2A).
A Radi pressure wire study (RADI Medical Systems AB, Uppsala, Sweden) was performed. The wire was advanced across the left main stem to the distal left anterior descending artery, and weight-adjusted adenosine was infused via the right femoral vein. The fractional flow reserve was 0.59 at maximal hyperemia (0.67 at rest; Figure 3A). Subclavian artery stenting with a 7.0×15-mm Xpress II stent was undertaken, with good angiographic results on repeat subclavian injection. The flow down the left internal mammary artery was immediately improved (Figure 2B). A repeat pressure wire study of the left main stem/left anterior descending artery showed an improved fractional flow reserve of 0.89 at maximal hyperemia (Figure 3B). The patient made an uneventful recovery and remained angina-free at 6 months’ follow-up.
At the time of writing, we are not aware of any previous objective demonstration of improvement in flow in the left anterior descending artery territory after subclavian stenting in patients with left internal mammary artery graft and subclavian stenosis.