Esprit BTK Post-Approval Study

Death was classified according to the underlying cause. Death within 30 days of the study procedure was classified as procedure-related unless medical history or autopsy findings demonstrated otherwise.

Cardiac death: Any death due to a proximate cardiac cause (e.g., MI, low-output failure, fatal arrhythmia), unwitnessed death, or death of unknown cause. Vascular death: Death caused by noncoronary vascular causes, such as cerebrovascular disease, pulmonary embolism, ruptured aortic aneurysm, dissecting aneurysm, or other vascular diseases. Non-cardiovascular death: Any death not covered by the above definitions, such as death caused by infection, malignancy, sepsis, pulmonary causes, accident, suicide, or trauma.

The definition of amputation applied only to amputations of the limb that was treated. Minor amputation referred to toe amputation(s), ray amputation(s) limited to the metatarsal head and distal half of the metatarsal bone, and trans-metatarsal amputation. Major amputation was defined as limb loss at or proximal to the transtibial level. Major amputations were specified as below-the-knee and above-the-knee amputations.

Freedom from above-ankle amputation in the treated limb and death

The ABI was the ratio of the ankle to arm pressure, and it was calculated by dividing the systolic blood pressure in the ankle of one leg by the higher of the two systolic blood pressures in the arms.

An ABI of 0.9-1.4 was considered within the normal range. A reduced ABI (less than 0.9) was consistent with peripheral artery occlusive disease, with values below 0.8 indicating moderate disease and values below 0.5 indicating severe disease. A value greater than 1.4 was considered abnormal, suggesting calcification of the arterial walls and noncompressible vessels, reflecting severe peripheral vascular disease.

The Rutherford Becker classification was defined as follows: Grade I (0) Asymptomatic, no hemodynamically significant occlusive disease. (1)Mild claudication. (2) Moderate claudication. (3) Severe claudication. Grade II (4)Ischemic rest pain. Grade III(5) Minor tissue loss, non-healing ulcer, or focal gangrene with diffuse pedal ischemia. (6) Major tissue loss extending above the transmetatarsal level, where the functional foot was no longer salvageable.

An index wound healing assessment log was required only for subjects who had a wound on the index limb at the time of the index procedure. This was intended to allow the healing of the index wound after treatment to be documented. All subjects that had a wound at the time of the index procedure are required to have an assessment by the site at each follow-up visit even if the index wound was healed at the previous visit. This will confirm that the index wound remains healed. If the index wound at the same location following healing has re-opened, the wound should still be assessed in the same index wound log.