Plaque rupture and morphological characteristics of the culprit lesion in acute coronary syndromes without significant angiographic lesion: analysis by intravascular ultrasound.

PURPOSE

To evaluate by intravascular ultrasound (IVUS) the characteristics of the culprit lesion with plaque rupture without significant angiographic stenosis after acute coronary syndromes (ACS).

PATIENTS AND METHODS

After ACS, IVUS was performed in 68 patients (46.8 years±11.9) without significant angiographic stenosis (31±15%). Plaque rupture was defined as a cavity within the plaque, communicating with the arterial lumen and having an overlying residual fibrous cap fragment. Qualitative analysis defined the type of plaque, and quantitative analysis evaluated plaque plus media area, plaque volume, plaque burden, and arterial remodeling index. Patients were divided into two groups: Group I with plaque rupture (25 patients) and Group II without plaque rupture (43 patients).

RESULTS

All patients with rupture showed soft or mixed plaque but no calcified plaque. In Group I, plaque rupture was associated with a larger plaque burden (49.8±12.3% vs. 39.8±12.1%, P<.0005), a more significant plaque plus media area (7.44±2.9 vs. 5.24±2.4mm(2), P<.001), a greater plaque volume (151.9±103.4 vs. 99.2±81.6mm(3), P<.007), and a higher ratio of plaque volume over length (8.0±3.8 vs. 5.6±3.7mm(3)/mm, P<.003). In Group I, positive remodeling was more frequent than intermediate remodeling (P<.03) or negative remodeling (P<.005). In Group II, there was no significant difference between the three types of remodeling.

CONCLUSION

The plaque ruptures responsible for ACS frequently appear on voluminous plaques with a large plaque burden and positive arterial remodeling.