Intravascular ultrasound findings in patients with very late stent thrombosis after either drug-eluting or bare-metal stent implantation

Abstract

Objectives: This study compared intravascular ultrasound (IVUS) findings at drug-eluting stent (DES) and bare-metal stent (BMS) sites in patients with very late stent thrombosis (VLST).

Background: VLST is being increasingly identified since the introduction of DES. VLST can also develop after BMS placement, but the underlying mechanisms remain unknown.

Methods: A total of 30 consecutive VLST patients with acute myocardial infarction (DES, n = 23; BMS, n = 7) were enrolled. Patients underwent IVUS examination before coronary angioplasty.

Results: The baseline characteristics were similar for the 2 groups, with the exception of reference vessel size, lesion length, stent length, minimal lumen diameter, and diameter stenosis after the procedure. Overall, VLST occurred at a mean 50.8 +/- 36.2 months after the index procedure, and occurred earlier after DES than BMS (33.2 +/- 12.5 months vs. 108.4 +/- 26.5 months, p < 0.001). IVUS variables were generally similar for the 2 groups. However, plaque burden at the distal reference segment, stent, and neointimal area of the in-stent segment were smaller in the DES group. Stent malapposition was observed in 73.9% of DES patients, but in no BMS patients (p = 0.001). Disease progression with neointimal rupture within the stent was observed in 10 DES patients (43.5%) and 7 BMS patients (100%; p = 0.010).

Conclusions: Stent malapposition was unique to DES-related VLST, whereas disease progression with neointimal rupture was more common in BMS patients. These findings suggest that different biological mechanisms underlie VLST development depending upon the stent type.