Algorithm Developed to Determine Need for Embolic Protection During Femoropopliteal Atherectomy

February 22, 2017—A study that sought to develop an algorithm for the use of distal embolic protection during atherectomy for femoropopliteal lesions was published by Prakash Krishnan, MD, et al in Journal of the American College of Cardiology (JACC): Cardiovascular Interventions (2017;10:403–410). The algorithm is based on angiographic lesion morphology and vascular anatomy of patients undergoing this procedure.

In comments to Endovascular Today, Dr. Krishnan explained, "These landmark findings allow the operator to use angiographic clues to predict embolization in real time, thereby allowing the use of distal embolic protection to prevent catastrophic complications while performing endovascular interventions to treat the claudicant population."

In the study, 508 patients with symptomatic lower extremity peripheral artery disease treated with atherectomy and distal embolic protection were evaluated to identify potential predictors of distal emboli. Distal embolization was defined as macroemboli present in the filter after atherectomy. Plaque collected from the SilverHawk directional atherectomy device (Medtronic) nose cone subset was sent for pathologic analysis to evaluate the accuracy of angiography in assessing plaque morphology.

As summarized in JACC: Cardiovascular Interventions, significant differences between the two groups (with macroemboli vs absence of macroemboli) were found in lesion length (142.1 ± 62.98 mm vs 56.91 ± 41.04 mm; P = .0001), low-density lipoprotein (82.3 ± 40.3 mg/dL vs. 70.9 ± 23.2 mg/dL; P = .0006), vessel runoff (1.18 ± 0.9 vs 1.8 ± 0.9; P = .0001), chronic total occlusion (131 vs 10; P = .001), in-stent restenosis (ISR; 33 vs 6; P = .0081), and calcified lesions (136 vs 65; P < .001). 

In simple logistic regression analysis, the investigators found that lesion length, reference vessel diameter, chronic total occlusion, runoff vessels, and ISR were strongly associated with macroemboli. Angiographic assessment of plaque morphology was accurate.

For calcium, there was a positive predictive value of 92.31, a negative predictive value of 95.35, sensitivity of 92.31%, and specificity of 95.35%. For atherosclerosis plaque, there was a positive predictive value of 95.56, a negative predictive value of 100, sensitivity of 100, and specificity of 92.31. Thrombus/ISR was correctly predicted, reported the investigators.

Chronic total occlusion, ISR, thrombotic, calcific lesions > 40 mm and atherosclerotic lesions > 140 mm identified by peripheral angiography necessitate concomitant filter use during atherectomy to prevent embolic complications, concluded the investigators in JACC: Cardiovascular Interventions.