Relation between renal function and neointimal tissue characteristics after drug-eluting stent implantation: Virtual histology-intravascular ultrasound analysis

Comparable neointimal healing in patients with stable coronary lesions and acute coronary syndrome: 3-month optical coherence tomography analysis

We aimed to assess a possible difference of the neointimal coverage status and its quality after implantation of the current-generation metallic stents in patients with acute coronary syndrome (ACS) vs. stable coronary lesions (non-ACS). We comprehensively analyzed three prospective single-center observational studies RESTORE (UMIN000033009), HEAL-BioFreedom (UMIN000029692), and HEAL-BioFreedom ACS (UMIN000034769). All patients who received successful optical coherence tomography (OCT) examination at planned 3-month follow-up after stent implantation were analyzed. Study population was divided into two groups, ACS vs. non-ACS groups. We evaluated standard OCT variables, coverage percent, and the quantitative light property values including light intensity, attenuation, and backscatter of neointima. A total of 177 lesions from 154 patients (ACS 44 lesions vs. non-ACS 133 lesions) were analyzed. At 3-month follow-up, coverage percent (ACS 91.5  ±  9.5% vs. non-ACS 91.8  ±  9.0%, P = 0.722) and neointimal thickness (ACS 59.5  ±  32.3 µm vs. non-ACS 58.2  ±  32.3 µm, P = 0.760) did not significantly differ. Light property values were similar between both groups (light intensity 159.29  ±  72.20 vs. 159.45   ± 63.78, P = 0.654; light attenuation 0.88  ±  0.26 vs. 0.87   ±  0.24 m^-1, P = 0.988; backscatter 4.86   ±  0.58 vs. 4.83   ±  0.57, P = 0.812). The similarity of the neointimal quality in ACS and non-ACS patients was consistent across the 6 different types of current-generation metallic stents (P for interaction  > 0.05). Our findings suggested the comparable neointimal characteristics 3 months after implantation of the current-generation metallic stents in patients with ACS and stable coronary lesions by quantitative OCT methodology.

Impact of neointimal tissue characterization and heterogeneity of bare-metal stents and drug-eluting stents on the time course after stent implantation evaluated by integrated backscatter intravascular ultrasound

Pathological studies have suggested the different process of in-stent restenosis (ISR) of bare-metal stents (BMS) and drug-eluting stents (DES). Here, we evaluated the components of neointimal tissue using integrated backscatter intravascular ultrasound (IB-IVUS) and focused on the time course after stent implantation and tissue signal distribution. We evaluated 125 lesions of 125 patients who underwent target lesion revascularization for ISR (BMS: n = 73, DES: n = 52). Volume analysis of a 4-mm length centered on a minimum lumen area in every 1-mm cross-sectional area was performed. For IB-IVUS analysis, color-coded maps were constructed from the default setting based on the integrated backscatter (IB) values (middle-IB value, green: fibrous and low-IB value, blue: lipid pool). For the neointimal tissue volume, we evaluated the ratios of the green (%G) and blue (%B) areas. Tissue signal distribution (TD) was also obtained from the default setting based on IB values in each pixel of IB-IVUS imaging. We compared values of neointimal tissues measured by IB-IVUS between the DES and BMS and time course. The observed period was longer after BMS implantation than after DES implantation (BMS: 2545 days, DES: 1233 days, p < 0.001). Overall, %G and %B were similar between the BMS and DES groups (%G: 55% and 51%, respectively, p = 0.10; %B: 36% and 38%, respectively, p = 0.51); however, TD was significantly higher in the DES group than in the BMS group (1091 vs. 1367, p < 0.001). TD in the DES group remained high during the follow-up periods. However, TD in the BMS group was low in the early phase and significantly increased over time (r = 0.56, p < 0.001). When analyzing the ISR within 2 years after stent implantation, the BMS was distinguished with a sensitivity of 66% and a specificity of 90% (cut-off value: TD = 1135, area under the curve 0.83, 95% confidence interval 0.74-0.92). TD could differentiate neointimal tissue after BMS implantation in the early phase. TD can be a useful index in the observation of neoatherosclerosis.

Impact of chronic kidney disease on platelet inhibition of clopidogrel and prasugrel in Japanese patients

BACKGROUND

The impact of chronic kidney disease (CKD) on the antiplatelet effect of clopidogrel and low-dose (3.75mg) prasugrel in Japanese patients is largely unknown.

METHODS

A total of 53 consecutive Japanese patients with stable coronary artery disease who received aspirin and clopidogrel were enrolled, and categorized by estimated glomerular filtration rate (eGFR): CKD group (n=15, eGFR<60ml/min/1.73m²) and non-CKD group (n=38, eGFR≥60ml/min/1.73m²). Clopidogrel was switched to 3.75mg prasugrel. Platelet reactivity measurement using the VerifyNow P2Y12 assay (Accumetrics, San Diego, CA, USA) was performed at baseline (on clopidogrel) and day 14 (on prasugrel).

RESULTS

The VerifyNow P2Y12 reaction units (PRU) during clopidogrel therapy was significantly higher in the CKD group than that in the non-CKD group (185.2±51.1 PRU vs. 224.3±57.0 PRU, p=0.02), whereas, the PRU with the prasugrel therapy in the CKD group and non-CKD group were not significantly different (149.9±51.1 PRU vs. 165.3±61.8 PRU, p=0.36). The PRU was significantly lower with the prasugrel therapy compared to that with the clopidogrel therapy both in the CKD group and in the non-CKD group.

CONCLUSIONS

Antiplatelet effect of clopidogrel but not prasugrel is attenuated in patients with CKD. Prasugrel achieves a consistently lower platelet reactivity compared with clopidogrel regardless of the presence of mild to moderate CKD.