October 4, 2014

Directional atherectomy for infra-inguinal atherosclerosis

What is directional atherectomy (DA)?

DA is a percutaneous technique that includes a directional cutter positioned to address the area of greatest plaque burden within a vessel and maximize luminal gain both above and below the knee. It is performed using the TurboHawk or SilverHawk devices manufactured by covedian. More details on the device including a video on how it works is available on the covedian website (http://www.turbohawkdevice.com/About).

Clinical rationale behind DA and DEFINITE LE Study:

POBA is largely limited by poor long-term patency rates and stenting leaves a re-stenotic nidus as well as limits future surgical bypass targets at the stented segment site. Therefore novel technologies such as DA have been designed to reduce atheroma burden at specific sites as well as preserve future surgical targets and the natural conformability of the vessel. The challenge that plagues such novel technologies is a lack of patient level data on their effectiveness and safety.

DEFINITE LE is a promising first step in addressing this knowledge gap for directional atherectomy (DA) devices. It is an industry funded (covedian) prospective, multinational, single-arm study designed to evaluate the short and long term (12-month) safety and effectiveness of DA for percutaneous treatment of 598 subjects with claudication and 201 subjects with critical limb ischemia (CLI) across 47 sites in the U.S. and Europe. Primary outcome was primary target lesion patency at 12 months for claudicants and freedom from major unplanned amputation of the target limb at 12 months in subjects with CLI. Both angiographic and duplex core lab adjudication was performed.

Key Findings in DEFINITE LE:

Limb preservation was achieved in 95% of CLI patients (much higher compared to contemporary surgical cohorts).
Primary one-year target vessel patency was 78% in claudicants (comparable to contemporary stent trials).
Alarmingly high (5.3%) arterial perforation rate with a stent bailout rate of 3.2%.
Interestingly, non-inferiority of this revascularization strategy in diabetic versus non-diabetic claudicants was demonstrated.
No difference in distal embolization with or without a filter but the overall distal embolization (3.8%) rate was too small to detect a statistical difference.

Take Home Points from DEFINITE LE:

Despite highly experienced operators, a high rate of arterial perforations in DEFINITE LE raises the need for enhancing device safety and further investigation is needed to refine patient selection in order to maximize clinical benefit with DA.

Overall, DA is a promising new technology but given single arm study design we still need randomized comparative data on safety and efficacy prior to embracing DA in routine clinical practice.

Given increasing cost considerations, one possible suggestion for future randomized trials in this field would be to embed them within existing large databases such as the newly launched ACC/NCDR PVI registry.