Cath Lab Digest

Intraprocedural Outcomes Following Distal Lower Extremity Embolization in Patients Undergoing Peripheral Percutaneous Interventions

Abstract

Distal embolization (DE) commonly occurs during peripheral percutaneous interventions (PPI). It is unknown how “significant” distal embolization requiring further pharmacologic and/or mechanical therapy affects intraprocedural variables, including procedure length, contrast use, and radiation exposure. Eighteen patients who experienced “significant” DE were compared to 38 patients who underwent PPI and experienced no DE requiring further therapy. Demographic and clinical variables were well matched. Partial correlation analysis was conducted with multiple procedural variables as controls. The following procedural variables correlated positively with “significant” distal embolization: more contrast use (P = 0.001) and longer procedural (P = 0.003) and fluoroscopy times (P = 0.001). We conclude that DE adversely prolongs the procedural time of a PPI and requires the use of more contrast and fluoroscopy.

Introduction

Distal embolization (DE) has been documented during the treatment of all vascular beds, including the coronaries,1 vein grafts2,3 carotids,4,5 renals,6,7 and in the lower extremities.8,9 DE in the lower extremities has been reported in patients with totally or subtotally occluded vessels, in moderately or severely calcified, long and irregular lesions, or in the presence of intravascular filling defect. Furthermore, patients undergoing rheolytic thrombectomy with or without thrombolysis and those treated with SilverHawk atherectomy (ev3, Plymouth, Minnesota) have been shown to experience significant lower extremity DE.9–14 In the recently completed PROTECT registry (Preventing lower extremity distal embolization using embolic filter protection),9 significant atheroembolization was seen in 45% of all patients treated with peripheral percutaneous interventions (PPI) captured in a distal embolic filter.

It is unclear how macroembolization leading to distal vessel occlusion or slow flow, and requiring further pharmacologic and/or mechanical therapy, influences intraprocedural and clinical outcomes. In this study we assess the impact of DE on procedural time, contrast utilization, and fluoroscopic use. Hospital length and overall major adverse events (MAE) are also reported.

Methods

In-hospital demographics, clinical and procedural variables were prospectively collected on 677 patients undergoing PPI at 2 medical centers using web-based, electronic case report forms. Data from patients who have experienced distal embolization requiring further pharmacologic and/or mechanical therapy (“significant DE”) were retrospectively reviewed from this main registry. Eighteen patients (2.6%) were identified and compared to 38 control patients with no significant DE. These control patients were previously enrolled in the PROTECT registry designed to assess the frequency of DE during PPI and the feasibility of embolic filter protection in capturing it.9 These patients were specifically selected because they were thoroughly evaluated using digital subtraction angiography for the presence or absence of DE as part of their enrollment in PROTECT and had similar demographic, clinical, and procedural variables collected.

Patients were divided into 2 groups:

a. Those who have experienced lower extremity DE that required further treatment as per operator judgment (“significant DE”) (group 1, n = 18)
b. Control patients that did not experience DE (group 2, n = 38).

The primary endpoints of the study were:

1. Contrast use (cc);
2. Total fluoroscopy time (minutes);
3. Length of procedure (minutes) defined from the start of sheath insertion in the groin to end of procedure as declared by the physician in the lab;
4. Hospital stay counted in days with each day defined as an overnight stay.

Furthermore, the combined rate of clinical MAE of death, unplanned amputation, unplanned urgent revascularization, acute renal failure, and blood loss requiring transfusions are also reported.

Data were audited by an independent clinical research monitor. Statistical analysis was performed by an experienced biostatistician. Since this was a pilot exploratory study, no predefined statistical assumptions were made. Descriptive analysis was performed on all variables. Univariate analysis between the 2 groups was performed. Continuous variables were compared using t-testing and dichotomous variables using chi-square (or Fisher exact) testing. The relationship between the endpoints of contrast use, hospital days, fluoroscopy time, and procedure length and DE was assessed using partial correlation analysis. Partial correlation analysis was performed to allow for the control of alternative antecedent variables that might affect the dependent endpoints in this study. The Partial correlation analysis was conducted with the following control variables: lesion diameter, TASC-D lesions, de novo lesions, total occlusions, below knee, thrombus in vessel, number of successfully treated vessels, device (PTA and PTA with stent versus SilverHawk and Excimer [Spectranetics, Colorado Springs, Colorado] laser), gender, and age.

Results