Abstract 5337: Morphological Characteristics of the Culprit Lesion Correlate With the Angiographic Flow Grade Following Thrombolysis in Myocardial Infarction. An Optical Coherence Tomography Study
Background: Intravenous thrombolysis fails to restore blood flow in a significant percentage of patients with ST-elevation myocardial infarction (STEMI). It remains unknown, whether certain morphological characteristics of the culprit lesion (CL) can predict the success of thrombolysis. We hypothesized that the thickness of the fibrous cap and the incidence of plaque rupture at the CL, as measured by Optical Coherence Tomography (OCT), may correlate with the outcome of thrombolysis.
Methods: We prospectively enrolled 55 consecutive patients with STEMI that were treated with thrombolysis 6 hours from symptom onset. All patients underwent coronary angiography within 24 hours from thrombolysis. We estimated TIMI flow grade and the corrected TIMI frame count (CTFC) for patients with TIMI flow II or III. In target vessels with TIMI flow grade ≤1 aspiration thrombectomy was performed. We then acquired OCT images from the CL. We measured the fibrous cap thickness (FCT) at the thinnest part overlying a lipid pool, the lipid content (in quadrants) and the incidence of plaque rupture, which was defined as the presence of fibrous-cap discontinuity.
Results: Of the total study population, 15 patients had TIMI flow 0 or I, 15 had TIMI flow II, and 25 had TIMI flow III. The number of lipid quadrants was greater in patients with TIMI flow 0-I than in patients with TIMI flow II and III (median 4, (range 1) vs. median 3 (range 2) vs. median 2 (range 1), p<0.001). The culprit lesion of the patients with TIMI flow 0 or I was more often characterized by a ruptured plaque compared to those with TIMI flow II and III (n=13 (86.67%) for TIMI 0–1, n=8 (53.33%) for TIMI II and n=6 (24%) for TIMI III, p<0.001). For patients with TIMI 0 and I, minimum FCT was 41±7μm, for patients with TIMI II 55±23μm and for those with TIMI III 87±26μm (p<0.001). In patients with TIMI flow II or III, a correlation was found between CTFC and the minimal cap thickness (r=−0.423, p=0.006).
Conclusion: In patients with STEMI, TIMI flow III following thrombolysis is associated with greater fibrous cap thickness, reduced lipid content and reduced incidence of plaque rupture in the CL. This study suggests that specific morphological features of the CL correlate with the flow grade following thrombolytic therapy in patients with STEMI.