2007 Abstracts: Subintimal Angioplasty for the Treatment of Claudication and Critical Limb Ischemia: 3-Year Results

Background: Subintimal angioplasty, or the intentional creation of an intimal dissection and channel across an arterial occlusion, was first reported in the European literature over 15 years ago. The technique was first used as a means of limb salvage in patients with critical limb ischemia who were unfit for surgical bypass. Today, subintimal angioplasty is employed in the United States by an increasing number of institutions, and with broadening indications. Published reports now describe its use in patients with disabling claudication, as a first-line therapy for patients who are otherwise operative candidates, and in patients with arterial occlusions anywhere from the aortoiliac region to the tibial vessels. Interest in the technique has increased as recent reports have demonstrated encouraging 12-month patency rates as high as 92%, with 12-month limb salvage achieved in as many as 94% of patients. Enthusiasm for subintimal angioplasty has been curtailed, however, by the relative lack of data regarding the procedure's ability to produce durable patency and lasting limb salvage. To better define these results, we reviewed our experience with subintimal angioplasty to determine 3-year patency and limb salvage rates in patients with disabling claudication or critical limb ischemia secondary to arterial occlusion.
Methods: In 2003, 109 patients underwent subintimal angioplasty of 110 occlusive lesions involving the iliac, superficial femoral, popliteal, or tibial arteries. The majority of procedures were performed in an angiographic suite; others in an operating room with C-arm fluoroscopy. A guidewire was passed to the level of the arterial occlusion, advanced in a subintimal plane across the lesion, and redirected into the true lumen. Balloon angioplasty was used to expand the subintimal channel and stents were placed at the discretion of the surgeon. Patients received heparin 100units/kg intravenously at the beginning of the procedure and clopidogrel 75mg daily for the first month. Technical success was defined as creation of a subintimal channel bypassing the occlusion, with residual angiographic stenosis < 30%. Patient follow-up included clinical assessment, measurement of ankle-brachial indices, and duplex examination of the treated segment every 3 months during the first year, every 6 months during the second year, and yearly thereafter. Statistical analysis was performed on an intention to treat basis.
Results: The mean age of patients undergoing subintimal angioplasty was 68±12 years. Sixty-two patients (57%) were male. Risk factors for peripheral vascular disease were present in 103 patients, including coronary artery disease (n=80, 72%), tobacco use (n=61, 56%), diabetes mellitus (n=57, 52%), and end-stage renal disease (n=13, 12%). Previous open bypass procedures had been performed in 12 patients (11%). Review of the medical record revealed 28 high-risk patients (26%) for whom open surgical bypass was believed to be contraindicated, while the remainder were either appropriate surgical candidates (n=59, 54%), or determination could not be made (n=22, 20%).
Patients with critical limb ischemia comprised 63% of the study population (n=69) while 37% of patients (n=41) underwent subintimal angioplasty for disabling claudication. The majority of patients were symptomatic due to occlusion of the superficial femoral artery alone, or the femoropopliteal segment (n=87, 79%). Eleven patients had occlusion of an iliac artery, 6 presented with an isolated popliteal artery occlusion, and 6 presented with an isolated tibial artery occlusion. Technical success was achieved in 95 procedures (86%) and stents were deployed in 23 of these (24%). In all but one patient, technical failure was due to an inability to advance the subintimal guidewire back into the true lumen. Re-entry devices were not routinely used or available during this time. Technical failures were evenly distributed among vascular territories.
Procedural complications occurred in 7 patients (6%), 2 of which required operative intervention. One obese, non-operative candidate who underwent successful subintimal angioplasty via femoral antegrade puncture developed a retroperitoneal hematoma requiring emergent evacuation and arteriotomy closure. Postoperatively, the patient suffered a myocardial infarction and ultimately died. The second patient developed a calf hematoma with compartment syndrome after perforation of the popliteal artery, requiring evacuation and fasciotomies. The remaining 5 complications consisted of minor hematomas and a single episode of distal embolization of debris.
Mean follow-up was 17 months (range, 0-43 months). During this period, 22 patients (20%) died and a total of 11 amputations were performed at the below-knee level or above (10%). Six of these amputations were performed for patients on whom subintimal angioplasty had been unsuccessful. A total of 22 open peripheral bypass operations were performed, 5 of which followed unsuccessful subintimal angioplasty. The remaining bypass operations were performed in patients who underwent successful subintimal angioplasty that later failed and required surgical revascularization.
By Kaplan-Meier analysis of all patients undergoing subintimal angioplasty, primary patency was 54%, 43%, and 32% at 1, 2, and 3 years respectively. Sixteen patients underwent a total of 17 percutaneous procedures to maintain patency of the SIA during the study period. This resulted in a primary assisted patency of 61%, 56%, and 54% at 1, 2, and 3 years, and secondary patency of 64%, 62%, and 61% at the same intervals. No open surgical interventions were required to maintain this patency.
Patients with rest pain, ischemic ulcers, or gangrene accounted for two-thirds of the study population. In this group, 38 of the patients (67%) obtained significant improvement in rest pain or healing of ischemic wounds. Limb salvage was achieved in 79%, 79%, and 72% of patients at 1, 2, and 3 years. Of the 21 high-risk patients for whom operative bypass was contraindicated, 10 have retained their limbs.
In patients who underwent subintimal angioplasty for disabling claudication, 30 patients (73%) have maintained significant improvement in walking distance or resolution of claudication. Surgical bypass procedures were performed in 10 patients (24%) during the study period and no amputations were required.
Conclusions: Subintimal angioplasty is a valuable and versatile tool in the care of patients with lower extremity arterial occlusion. For treatment of critical limb ischemia, our findings suggest that patients can expect a 67% chance of clinical improvement following subintimal angioplasty, with limb salvage of >70% at three years. For patients with disabling claudication, nearly 75% can expect clinical improvement after subintimal angioplasty with minimal risk of progression to critical ischemia or limb loss. And for the unfortunate patients who are poor candidates for surgical bypass and facing amputation, the procedure offers patients a nearly 50% chance of limb preservation.
Our results more clearly define the 3-year horizon for patients treated with subintimal angioplasty, and are particularly encouraging for three reasons. First, the primary patency of subintimal angioplasty is now comparable to that of prosthetic bypass, and when maintained with additional percutaneous interventions as needed, its patency approaches that of autologous bypass. This "secondary patency" is much more appealing in the context of percutaneous techniques, where procedures to maintain or restore patency consist of a groin puncture rather than a second or third operation in patients with substantial cardiac risk. Unlike previous studies that have demonstrated significant reductions in assisted patency after 12-24 months, our results suggest that with routine surveillance and early percutaneous intervention, the secondary patency of this technique is quite durable through 3 years. In addition, these results come from our early experience with subintimal angioplasty that now totals over 800 procedures. With increased surgeon experience and the introduction of re-entry devices, we suspect technical success and patient outcomes are continuing to improve.
Second, our results demonstrate that subintimal angioplasty and surgical bypass are not mutually exclusive. There is no evidence in our data, nor in previous reports, that subintimal angioplasty jeopardizes the potential for surgical bypass if required in the future. Likewise, there is no evidence the technique compromises lower extremity perfusion or risks limb loss in the event of technical failure.
Finally, these results further legitimize the use of subintimal angioplasty as a first-line therapy in patients with occlusive disease who prefer an endovascular procedure over surgical bypass. The procedure is safe, effective, minimally invasive, and is a particularly appealing therapeutic option for high-risk patients.