Author + information
- Received June 30, 2017
- Accepted July 11, 2017
- Published online August 30, 2017.
- Naotaka Okamoto, MD,
- Yuliya Vengrenyuk, PhD,
- Usman Baber, MD and
- Annapoorna S. Kini, MD∗ ()
- Division of Cardiology, Mount Sinai Hospital and Icahn School of Medicine at Mount Sinai, New York, New York
- ↵∗Address for correspondence:
Dr. Annapoorna S. Kini, Division of Cardiology, Mount Sinai Hospital, One Gustave L. Levy Place, Box 1030, New York, New York 10029.
A 73-year-old man who smokes presented to the emergency room with inferior ST-segment elevation myocardial infarction. The patient was loaded with 325-mg aspirin and 180-mg ticagrelor, and was immediately taken to the cardiac catheterization laboratory. Coronary angiography (CAG) revealed thrombotic occlusion of the right coronary artery (RCA) (Figure 1A1) and a high-grade lesion in the mid-left anterior descending artery. The culprit RCA lesion was treated with mechanical thrombus aspiration followed by deployment of a single 4 × 20-mm drug-eluting stent with no residual stenosis and adequate flow (Figure 1A2). The patient was admitted with a plan for nonculprit percutaneous coronary intervention of the left anterior descending artery lesion within 48 h. In the intervening period, the patient was asymptomatic. Diagnostic angiography 2 days later revealed a high-grade lesion in the mid-portion of the RCA stent (Figure 1A3) that was interrogated using optical coherence tomography (OCT), revealing a 7-mm nonocclusive red thrombus in the proximal part of the stent (Figures 1B1 to 1B3 and 1C, Online Video 1). OCT confirmed satisfactory stent expansion at the site of thrombus formation (Figure 1B2). We performed balloon dilatation with a 4.5-mm noncompliant balloon within the stent, which resulted in a significant reduction of thrombus and sufficient lesion dilatation by angiography (Figures 2A1 and 2A2) with TIMI (Thrombolysis In Myocardial Infarction) flow grade 3. OCT pullback further confirmed disappearance of the thrombus (Figures 2B1 to 2B3) and improved stent expansion (Figure 2B2, Online Video 2).
Stent underexpansion and incomplete stent apposition have been shown to be predominant mechanisms of acute or subacute stent thrombosis (1). Although the presented case cannot be classified as stent thrombosis due to the lack of clinical or electrical signs and symptoms, it could have developed into a subacute stent thrombosis. We believe that the mechanism of thrombus development in this case could be a residual thrombotic mass behind the stent in a positively remodeled vessel. Although we were not able to assess the remodeling with OCT, the vessel could have had a positive remodeling at the primary percutaneous coronary intervention. A 31% increase in mean stent diameter after balloon dilatation strongly supports our hypothesis. A mildly underexpanded and incompletely apposed stent in the positive remodeling vessel would promote the thrombus formation in this case.
In conclusion, the case demonstrated a possibility of asymptomatic development of a thrombus after satisfactory stent deployment based on angiography alone in an ST-segment elevation myocardial infarction patient on optimal medical therapy.
For supplemental videos and their legends, please see the online version of this paper.
The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Received June 30, 2017.
- Accepted July 11, 2017.
- 2017 American College of Cardiology Foundation