Abstract 14615: Clinical and Morphological Presentations of Acute Coronary Syndrome without Coronary Plaque Rupture - An Intravascular Ultrasound Study -
Background: Pathological studies have indicated that representative lesions responsible for acute coronary syndrome (ACS) are ruptures of vulnerable plaques with a superimposed thrombosis; however, precise mechanisms underlying ACS without plaque ruptures have not been well studied in vivo. We sought to examine clinical, angiographic and intravascular ultrasound (IVUS) characteristics of ACS without plaque ruptures.
Methods and Results: Culprit lesions of 161 ACS patients were clearly visualized with preintervention IVUS imaging. These culprit lesions were classified into two groups based on the presence or absence of plaque rupture (Rupture group: n=57, Non-rupture group: n=104). Clinical characteristics and lesion morphologies were compared between the two groups. Coronary vasospasm was defined based on Guidelines for Diagnosis and Treatment of Patients With Vasospastic Angina (VSA) by Japanese Circulation Society Joint Working Group. Clinical demographics were identical between the groups except lower abdominal circumference (86±10cm vs 90±9cm, p=0.02) and lower prevalence of myocardial infarction (53% vs 82%, p=0.0002) in Non-rupture group. The incidence of definite VSA was significantly higher in Non-rupture group than in Rupture group (15% vs 2%, p=0.006). Morphologically, Non-rupture group was associated with simpler Ambrose classification (36% vs 14%, p=0.004), less hypoechoic tissue of culprit plaque (45% vs 65%, p=0.04) and lower incidence of IVUS-detected thrombus (21% vs 54%, p<0.0001), compared with Rupture group. On quantitative IVUS, although minimum lumen area (MLA) was similar between the groups, vessel (14.2±5.4mm2 vs 17.5±5.1mm2, p=0.0002) and plaque (11.6±5.0mm2 vs 14.9±4.9mm2, p<0.0001) areas were significantly smaller at MLA site in Non-rupture group than in Rupture group. On multivariate analysis, average plaque area was only an independent IVUS predictor of non-rupture ACS (odds ratio: 0.85, p=0.01).
Conclusion: Compared to ACS with plaque rupture, non-rupture ACS arise from more hyperechoic (allegedly “stable”) plaque with smaller vessel and plaque area, leading to lower incidence of thrombotic occlusion. Coronary vasospasm might be a possible pathogenic mechanism underlying non-rupture ACS.
- Acute coronary syndromes
- Plaque rupture
- Intravascular ultrasound/Doppler
- Coronary vasospasm
- Cardiovascular imaging
- © 2012 by American Heart Association, Inc.