Intravascular Ultrasound Analysis of Intraplaque Versus Subintimal Tracking in Percutaneous Intervention for Coronary Chronic Total Occlusions and Association With Procedural Outcomes

Abstract

Objectives: Using intravascular ultrasound (IVUS), the authors compared outcomes by observed wire position (intraplaque vs. subintimal) achieved during successful chronic total occlusion (CTO) lesion treatment.

Background: Recent successes in CTO percutaneous coronary intervention (PCI) have used both intraluminal and subintimal wire tracking to improve procedural success. IVUS may be used to determine the course of wire tracking after crossing a CTO.

Methods: From March 2014 to March 2016, data were collected into a single-center database from 219 patients undergoing CTO PCI with concomitant IVUS imaging. IVUS-visualized wire tracking patterns were then retrospectively examined. Clinical outcomes with a composite in-hospital cardiovascular endpoint of all-cause death, periprocedural myocardial infarction, and in-hospital target lesion revascularization were analyzed along with IVUS-detected vascular injury.

Results: Of the 524 lesions assessed, 219 patients with successfully recanalized CTO lesions had adequate IVUS imaging and were included. Subintimal tracking was detected in 52.1% of overall cases (86.7% dissection re-entry, 27.9% wire escalation). Minimal stent area of the CTO segment and prevalence of significant edge dissection were similar in the 2 groups. In the subintimal tracking group, there was a higher rate of the composite endpoint, mostly driven by periprocedural myocardial infarction. Subintimal tracking was associated with significantly greater IVUS-detected vascular injury, angiographic dye staining/extravasation, and branch occlusion.

Conclusions: IVUS-detected subintimal tracking is observed in approximately one-half of all successful CTO PCI cases and is associated with an expected higher, yet acceptable, event rate with no difference in minimal stent area or edge dissection among patients undergoing contemporary hybrid CTO PCI.

Keywords: chronic total occlusion; intravascular ultrasound; percutaneous coronary intervention.

FIGURE 1. Flow Chart of Patient Inclusion in the Current Study

*IVUS visualized. CTO = chronic total occlusion; IVUS = intravascular ultrasound; PCI = percutaneous coronary intervention.

FIGURE 2. Example of Intraplaque and Subintimal Guidewire Tracking

(A1) The expected angiographic route of the CTO is marked by dashed lines. (A2) Intraplaque tracking shown using IVUS after pre-dilation. The arrow in A1 marks the location of the IVUS cross section (A2) where the IVUS catheter is located in the center of the plaque. Post-stent angiogram (B1) and IVUS (B2). The arrow in B1 shows the location of the IVUS catheter location for the cross-sectional imagine (B2) demonstrating full stent expansion. (C1) The expected angiographic route of the CTO is again marked by dashed lines. (C2) Subintimal tracking shown using IVUS after pre-dilation (C2). The arrow in C1 shows the location of the IVUS cross-section (C2) with the IVUS catheter in the subintimal space (arrowheads). Subintimal catheter position is indicated by the absence of 3 layers of arterial wall and the presence of the collapsed true lumen (arrow seen at 6 to 8 o’clock). Post-stent angiogram (D1) and IVUS (D2). The arrow in D1 shows the location of the IVUS cross-section corresponding to the stent (arrowheads in D2) in subintimal space which is compressing the true lumen behind the stent at 5 to 11 o’clock. Abbreviations as in Figure 1.

FIGURE 3. Representative Images of IVUS-VI

(A) Intramedial hematoma, defined as an accumulation of blood (arrowheads) that appear as a crescent-shaped homogeneous hyperechoic structure within the medial space. (B) Perivascular hematoma, defined as an accumulation of blood (arrowheads) that appear as a crescent-shaped homogeneous hyperechoic structure outside the vessel wall, visually continuous with the adventitia or peri-adventitial structures. (C) Perivascular blood speckle, defined as free blood speckle (arrowheads) and new echolucent structures outside the vessel wall, with or without communication with the lumen. IVUS = intravascular ultrasound; VI = vascular injury.

FIGURE 4. Guidewire Tracking Pattern Compared With Angiography-Defined Successful Approach and Difficulty Grades

(A) Guidewire tracking pattern and successful approach by angiography. (B) Guidewire tracking pattern and difficulty grades. ADR = antegrade dissection re-entry; AWE = antegrade wire escalation; J-CTO = Multicenter CTO Registry in Japan; RDR = retrograde dissection re-entry; RWE = retrograde wire escalation.

FIGURE 5. Procedure-Related Complications During CTO Intervention

(A) Complications detected by angiography. (B) Complications detected by IVUS. *Perforation requiring treatment with pericardiocentesis, covered stent, or surgery; †malapposition area >10% lumen area; ‡protruded tissue area >10% stent area; §dissection >3 mm in length and >60° in angle. MSA = minimum stent area; other abbreviations as in Figure 1.