Intravascular ultrasound-guided optimization for chronic total occlusion-percutaneous coronary intervention with multiple drug-eluting stents

Background

Multiple stenting in the chronic total occlusion (CTO) lesions is frequently required, however associated with poorer clinical outcomes. It is demonstrated that intravascular ultrasound (IVUS)-guided CTO-percutaneous coronary intervention (PCI) is related to a lower risk of adverse clinical events.

Purpose

We aimed to evaluate the clinical impact of stent optimization under IVUS guidance for multiple stenting, comparing with single stenting.

Methods

A total of 916 patients receiving drug-eluting stent (DES) under IVUS guidance were classified into two groups (stent optimization and non-optimization) according to optimization criteria (an absolute expansion criteria; minimal stent area ≥4.9 mm2 and a relative expansion criteria; 80% of mean reference lumen area). Of total population, 314 patients (34.3%) were treated with single stent and 575 patients (62.7%) were treated with multiple stents, respectively. Ischemic-driven target-lesion revascularization (TLR)/reocclusion was evaluated.

Results

Under IVUS guidance, 316 patients (34.5%) met IVUS criteria for stent optimization The achieving rates were 53% in the single stent group and 24% in the multiple stents group, respectively, (p<0.001). During a median of 4.7 years, the multiple stent group showed a significantly higher TLR/reocclusion rate, compared with the single stent group (12.8% vs. 5.2%, adjusted hazard ratio [HR] 2.51, 95% confidence interval [CI] 1.20–5.25, p=0.01). (Figure 1) Meeting both the absolute and relative expansion criteria was associated with a significantly low rate of TLR/reocclusion rate (12.5% vs. 5.2%, adjusted HR 0.34, 95% CI: 0.15–0.79, p=0.01). Under IVUS-guidance, there was no significant difference between multiple stenting and single stenting in case of achieving the optimization criteria (6.5% vs. 4.2%, p=0.11), whereas non-optimization group in the patients with multiple stenting showed a significantly higher rate of TLR/reocclusion, compared with IVUS-optimization group in the patients with single stenting (14.5% vs. 4.2%, p=0.002). (Figure 2)

Conclusions

In CTO-PCI with DES, multiple stenting significantly increased the risk of TLR/reocclusion. IVUS-guided optimization for multiple stenting showed a comparable long-term risk of TLR/reocclusion to single stenting with IVUS optimization. Hence, achieving IVUS expansion criteria may help to reduce the risk of TLR/reocclusion in CTO-PCI with multiple DES overlapping.

Funding Acknowledgement

Type of funding sources: None.

Phylogenetic relationships among Acanthamoeba spp. based on PCR-RFLP analyses of mitochondrial small subunit rRNA gene

We investigated the value of mitochondrial small subunit rRNA gene (mt SSU rDNA) PCR-RFLP as a taxonomic tool for Acanthamoeba isolates with close inter-relationships. Twenty-five isolates representing 20 species were included in the analysis. As in nuclear 18S rDNA analysis, two type strains (A. astronyxis and A. tubiashi) of morphological group 1 diverged earliest from the other strains, but the divergence between them was less than in 18S riboprinting. Acanthamoeba griffini of morphological group 2 branched between pathogenic (A. culbertsoni A-1 and A. healyi OC-3A) and nonpathogenic (A. palestinensis Reich, A. pustulosa GE-3a, A. royreba Oak Ridge, and A lenticulata PD2S) strains of morphological group 3. Among the remaining isolates of morphological group 2, the Chang strain had the identical mitochondrial riboprints as the type strain of A. hatchetti. AA2 and AA1, the type strains of A. divionensis and A. paradivionensis, respectively, had the identical riboprints as A. quina Vil3 and A. castellanii Ma. Although the branching orders of A. castellanii Neff, A. polyphaga P23, A. triangularis SH621, and A. lugdunensis L3a were different from those in 18S riboprinting analysis, the results obtained from this study generally coincided well with those from 18S riboprinting. Mitochondrial riboprinting may have an advantage over nuclear 18S rDNA riboprinting because the mt SSU rDNAs do not seem to have introns that are found in the 18S genes of Acanthamoeba and that distort phylogenetic analyses.

Subgenus classification of Acanthamoeba by riboprinting

Subgenus classification of Acanthamoeba remains uncertain. Twenty-three reference strains of Acanthamoeba including 18 (neo)type-strains were subjected for classification at the subgenus level by riboprinting. PCR/RFLP analysis of 18S rRNA gene (rDNA). On the dendrogram reconstructed on the basis of riboprint analyses, two type-strains (A. astronyxis and A. tubiashi) of morphological group 1 diverged early from the other strains and were quite distinct from each other. Four type-strains of morphological group 3, A. culbertsoni, A. palestinensis, A. healyi were considered taxonomically valid, but A. pustulosa was regarded as an invalid synonym of A. palestinensis. Strains of morphological group 2 were classified into 6 subgroups. Among them, A. griffini which has an intron in its 18S rDNA was the most divergent from the remaining strains. Acanthamoeba castellanii Castellani, A. quina Vil3, A. lugdunensis L3a, A. polyphaga Jones, A. triangularis SH621, and A. castellanii Ma strains belonged to a subgroup, A. castellanii complex. However, A. quina and A. lugdunensis were regarded as synonyms of A. castellanii. The Chang strain could be regarded as A. hatchetti. Acanthamoeba mauritaniensis, A. divionensis, A. paradivionensis could be considered as synonyms of A. rhysodes. Neff strain was regarded as A. polyphaga rather than as A. castellanii. It is likely that riboprinting can be applied for rapid identification of Acanthamoeba isolated from the clinical specimens and environments.