Quantitative Angiography Should Not Be the Gold Standard in Assessment of Infrapopliteal Arterial Disease

Hello, and welcome to the March issue of  Vascular Disease Management. I have chosen to comment on Dr Nicolas Shammas and colleagues’ case report entitled “The Nature of Dissections in Infrapopliteal Arteries: Insights from Intravascular Ultrasound Imaging.” I will specifically comment on the treatment of the infrapopliteal segment of disease.

In this case report, a patient presenting with a non-healing left heel ulcer was noted by angiography to have severe peripheral atherosclerotic obstructive disease consisting of distal left superficial femoral in-stent restenosis, popliteal artery occlusion, and total occlusion of all proximal infrapopliteal arteries with distal collateral filling of the anterior tibial artery. 

The patient was treated via interventional technique. Contralateral femoral access was obtained by which angiography was performed. Attempts at crossing the occluded segment antegrade were unsuccessful; therefore, anterior tibial pedal access was obtained. The anterior tibial occlusion was crossed in retrograde manner utilizing duplex guidance to ensure intraluminal crossing. Subsequent to retrograde wire crossing, intravascular ultrasound (IVUS) was performed. IVUS disclosed that the anterior tibial vessel size was significantly larger than the size measured by quantitative angiography, and that there was a 360° arc of medial calcium that was not discerned by quantitative angiography. On the basis of the ultrasound findings, a larger balloon capable of achieving higher pressure dilation was chosen than would have been mandated by quantitative angiography. 

IVUS performed after angioplasty disclosed evidence of a dissection that was classified as C2 by Dr Shammas’ IVUS-based grading classification (C denoting the depth of dissection and 2 denoting the injury involving greater than 180° of the arterial circumference.) Based on the post-angioplasty IVUS findings, two 4 mm balloon-expandable stents were implanted at the origin of the anterior tibial artery with high pressure technique resulting in an excellent final lumen, sealing of the dissection, and brisk arterial flow. The popliteal and superficial femoral arteries were treated with a drug-eluting self-expanding stent and a drug-coated balloon, respectively.

This article clearly points out many of the challenges encountered by interventionalists treating infrapopliteal arteries. As compared to the femoral and popliteal arteries, these vessels are smaller in diameter, often have fibrotic or calcific rings, are more difficult to image because of underlying bone or vessel overlap, and often involve branch points. They are typically undersized by quantitative angiography. It has been my personal experience that angiography often fails to identify areas of significant obstructive disease detected by IVUS. All these factors may contribute to the poor reported patency rates of tibial vessels following interventional therapy. Tibial patency is paramount in cases of limb salvage, particularly those in which only infrapopliteal artery disease is present. 

Ultimately, long-term vascular patency is probably related to the initial lumen size created at the time of intervention and the subsequent loss of lumen secondary to vascular healing or thrombosis. Quantitative angiography is not as accurate as IVUS or optical coherence tomography (OCT) in determining true vessel size or plaque composition. Quantitative angiography is not as accurate in detecting dissections, and it may fail to discern all obstructive lesions. I believe that quantitative angiography should no longer be thought of as the gold standard in assessing infrapopliteal arterial disease, particularly if new treatment modalities prove to be effective in treating medial calcification with decreased rates of significant dissections.

Achieving long-term patency following infrapopliteal intervention, particularly in long calcified lesions, has been an elusive goal. Perhaps guidance via OCT or IVUS, coupled with new therapies that modify plaque, may assist in improving patency and outcomes by facilitating optimization of the initial lumen and by better detecting and treating dissections that may negatively impact short- and long-term patency. It is time for a randomized trial evaluating IVUS or OCT guidance compared with quantitative angiography in the interventional therapy of infrapopliteal arterial disease. A trial could answer whether or not routine use of IVUS is cost-effective and if it yields more durable clinical benefit.