Optical coherence tomography versus intravascular ultrasound to evaluate coronary artery disease and percutaneous coronary intervention

OBJECTIVES

We compared intravascular ultrasound (IVUS) and 2 different generations of optical coherence tomography (OCT)-time-domain OCT (TD-OCT) and frequency-domain OCT (FD-OCT)-for the assessment of coronary disease and percutaneous coronary intervention (PCI) using stents.

BACKGROUND

OCT is a promising light-based intravascular imaging modality with higher resolution than IVUS. However, the paucity of data on OCT image quantification has limited its application in clinical practice.

METHODS

A total of 227 matched OCT and IVUS pull backs were studied. One hundred FD-OCT and IVUS pull backs in nonstented (n = 56) and stented (n = 44) vessels were compared. Additionally, 127 matched TD-OCT and IVUS images were compared in stented vessels.

RESULTS

FD-OCT depicted more severe native coronary disease than IVUS; minimal lumen area (MLA) was 2.33 ± 1.56 mm(2) versus 3.32 ± 1.92 mm(2), respectively (p < 0.001). Reference vessel dimensions were equivalent between FD-OCT and IVUS in both native and stented coronaries, but TD-OCT detected smaller reference lumen size compared with IVUS. Immediately post-PCI, in-stent MLAs were similar between FD-OCT and IVUS, but at follow-up, both FD-OCT and TD-OCT detected smaller MLAs than did IVUS, likely due to better detection of neointimal hyperplasia (NIH). Post-PCI malapposition and tissue prolapse were more frequently identified by FD-OCT.

CONCLUSIONS

FD-OCT generates similar reference lumen dimensions but higher degrees of disease severity and NIH, as well as better detection of malapposition and tissue prolapse compared with IVUS. First-generation TD-OCT was associated with smaller reference vessel dimensions compared with IVUS.

Volumetric assessment of lesion severity with optical coherence tomography: relationship with fractional flow

AIMS

Frequency-domain optical coherence tomography (FD-OCT) provides a rapid tomographic scan of a coronary vessel, with an accurate reconstruction of its lumen profile. An FD-OCT-based metric that corresponds more closely with physiological significance of lesions may enable more precise guidance of interventional procedures. The aim of this feasibility study was to evaluate a new method for quantifying coronary lesion severity that estimates hyperaemic flow resistance of branched vessel segments imaged by FD-OCT.

METHODS AND RESULTS

An analytical flow model was developed that relates fractional flow reserve (FFR) to the vascular resistance ratio (VRR), a measure of blood flow resistance derived from volumetric FD-OCT lumen profiles. The VRR-FFR relationship was evaluated in 21 patients on whom both pressure measurement and FD-OCT imaging were performed in a random order during maximal hyperaemia. Lesion severity assessed by VRR showed a stronger linear correlation with FFR measurements (before model optimisation [blinded]: r=0.81; p<0.001; root mean square error [RMSE]=0.095 FFR units; after model optimisation [unblinded]: r=0.91; p<0.001; RMSE=0.066 FFR units) than quantitative coronary angiography and FD-OCT-derived measurements of minimum lumen area (r=0.67; p=0.0012) and per cent area stenosis (r=-0.61; p=0.004).

CONCLUSIONS

Accurate volumetric measurement of the lumen profile with FD-OCT correlates more closely with FFR than standard metrics derived from single image cross-sections. VRR shows promise as a method for evaluating lesion severity.

Optical coherence tomography evidence of endothelial erosion as a cause of ST-segment elevation myocardial infarction

High-resolution intracoronary imaging provided relevant insights into the field of pathophysiology of acute coronary syndromes (ACS). Human autopsy studies have shown that endothelial erosion may lead to intravascular thrombosis and acute myocardial infarction. We report the case of a 51-year-old woman presenting with ST-segment elevation ACS. In this patient, frequency domain optical coherence tomography (FD-OCT) was performed into the infarct-related artery, showing in-vivo findings suggestive of endothelial erosion, associated with no flow-obstructing luminal thrombus. In this rare case, endothelial erosion, and subsequent thrombosis, in the proximal third of the artery has probably caused embolization and thrombotic occlusion in the mid third. FD-OCT allowed us to obtain a rare in-vivo image of endothelial erosion, providing relevant insights into the setting of ACS.

Examination of the in vivo mechanisms of late drug-eluting stent thrombosis: findings from optical coherence tomography and intravascular ultrasound imaging

OBJECTIVES

This study investigated the role of uncovered stent struts on late stent thrombosis (LST) after drug-eluting stent (DES) implantation with optical coherence tomography (OCT).

BACKGROUND

Autopsy studies have identified delayed healing and lack of endothelialization of DES struts as the hallmarks of LST. DES strut coverage has not previously been examined in vivo in patients with LST.

METHODS

We studied 54 patients, including 18 with DES LST (median 615 days after implant) undergoing emergent percutaneous coronary interventions and 36 matched DES control subjects undergoing routine repeat OCT and intravascular ultrasound (IVUS) who did not experience LST for ≥3 years. Thrombus aspiration was performed during emergent percutaneous coronary intervention before OCT and IVUS assessment.

RESULTS

By OCT, patients with LST--compared with control subjects--had a higher percentage of uncovered (median [interquartile range]) (12.27 [5.50 to 23.33] vs. 4.14 [3.00 to 6.22], p < 0.001) and malapposed (4.60 [1.85 to 7.19] vs. 1.81 [0.00 to 2.99], p < 0.001) struts. The mean neointimal thickness was similar in the 2 groups (0.23 ± 0.17 mm vs. 0.17 ± 0.09 mm, p = 0.28). By IVUS, stent expansion was comparable in the 2 groups, although positive remodeling was increased in patients with LST (mean vessel cross-section area 19.4 ± 5.8 mm(2) vs. 15.1 ± 4.6 mm(2), p = 0.003). Thrombus aspiration demonstrated neutrophils and eosinophils in most cases. By multivariable analysis, the length of segment with uncovered stent struts by OCT and the remodeling index by IVUS were independent predictors of LST.

CONCLUSIONS

In this in vivo case-controlled study, the presence of uncovered stent struts as assessed by OCT and positive vessel remodeling as imaged by IVUS were associated with LST after DES.

Consensus standards for acquisition, measurement, and reporting of intravascular optical coherence tomography studies: a report from the International Working Group for Intravascular Optical Coherence Tomography Standardization and Validation

OBJECTIVES

The purpose of this document is to make the output of the International Working Group for Intravascular Optical Coherence Tomography (IWG-IVOCT) Standardization and Validation available to medical and scientific communities, through a peer-reviewed publication, in the interest of improving the diagnosis and treatment of patients with atherosclerosis, including coronary artery disease.

BACKGROUND

Intravascular optical coherence tomography (IVOCT) is a catheter-based modality that acquires images at a resolution of ~10 μm, enabling visualization of blood vessel wall microstructure in vivo at an unprecedented level of detail. IVOCT devices are now commercially available worldwide, there is an active user base, and the interest in using this technology is growing. Incorporation of IVOCT in research and daily clinical practice can be facilitated by the development of uniform terminology and consensus-based standards on use of the technology, interpretation of the images, and reporting of IVOCT results.

METHODS

The IWG-IVOCT, comprising more than 260 academic and industry members from Asia, Europe, and the United States, formed in 2008 and convened on the topic of IVOCT standardization through a series of 9 national and international meetings.

RESULTS

Knowledge and recommendations from this group on key areas within the IVOCT field were assembled to generate this consensus document, authored by the Writing Committee, composed of academicians who have participated in meetings and/or writing of the text.

CONCLUSIONS

This document may be broadly used as a standard reference regarding the current state of the IVOCT imaging modality, intended for researchers and clinicians who use IVOCT and analyze IVOCT data.

Prevalence, predictors, and long-term prognosis of premature discontinuation of oral antiplatelet therapy after drug eluting stent implantation

To date, limited information is available on the long-term discontinuation rates of antiplatelet therapy after drug-eluting stent implantation. The aim of the present study was to determine the prevalence and predictors of premature discontinuation of oral antiplatelet therapy after drug-eluting stent implantation and to evaluate its effects on long-term prognosis. We studied 1,358 consecutive patients successfully treated with drug-eluting stents and discharged with dual oral antiplatelet therapy. Aspirin was to be maintained lifelong, and clopidogrel was prescribed for 12 months. The patients were followed for 36 months. The prevalence and predictors of aspirin and clopidogrel discontinuation were assessed. Major adverse cardiac events, defined as death, myocardial infarction, destabilizing symptoms leading to hospitalization, and nonfatal stroke, were recorded. Definite, probable, and possible stent thrombosis (ST) and major and minor bleeding were also determined. Of the 1,358 patients, 8.8% had discontinued one or both antiplatelet agents within the first 12 months ("early" discontinuation) and 4.8% had discontinued aspirin after 1 year ("late" discontinuation). Early discontinuation was predicted by in-hospital major bleeding, the use of oral anticoagulants at discharge, and the lack of a statin prescription. Previous stroke was the only independent predictor of late discontinuation. Patients with early discontinuation experienced a greater incidence of major adverse cardiac events (28.6% vs 13.7%, p <0.001) and ST (7.6% vs 3.4%, p = 0.038). All-cause mortality (13.4% vs 4.7%, p <0.001) and cardiovascular death (5% vs 1.2%, p = 0.007) were significantly more frequent among patients with early discontinuation. In patients with late discontinuation, a nonstatistically significant increase was seen in major adverse cardiac events (20% vs 13.3%, p = 0.128) and ST (6.2% vs 3.2%, p = 0.275). In conclusion, premature discontinuation of antiplatelet therapy is relatively common, especially within the first year, and strongly associated with increased cardiovascular events, including ST and death.

Strut coverage and late malapposition with paclitaxel-eluting stents compared with bare metal stents in acute myocardial infarction: optical coherence tomography substudy of the Harmonizing Outcomes with Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) Trial

BACKGROUND

The safety of drug-eluting stents in ST-segment elevation myocardial infarction (STEMI) continues to be debated. Pathological studies have demonstrated an association between uncovered struts and subsequent stent thrombosis. Optical coherence tomography can detect stent strut coverage in vivo on a micron-scale level. We therefore used optical coherence tomography to examine strut coverage in patients with STEMI treated with paclitaxel-eluting stents (PES) and bare metal stents (BMS).

METHODS AND RESULTS

In the Harmonizing Outcomes With Revascularization and Stents in Acute Myocardial Infarction (HORIZONS-AMI) trial, patients with STEMI were randomized 3:1 to PES or BMS implantation. In a formal substudy, optical coherence tomography at 13 months was performed in 118 consecutive randomized patients (89 PES, 29 BMS) in whom 188 stents were assessed (146 PES and 42 BMS). A total of 44 139 stent struts were analyzed by an independent core laboratory blinded to stent assignment. The primary prespecified end point, the percentage of uncovered stent struts per lesion at follow-up, was 1.1 ± 2.5% in BMS lesions versus 5.7 ± 7.0% in PES lesions (P < 0.0001). Malapposed struts were observed in 0.1 ± 0.2% of BMS lesions versus 0.9 ± 2.1% of PES lesions (P = 0.0003). Percentage net volume obstruction was 36.0 ± 15.4% with BMS and 19.2 ± 11.3% with PES (P < 0.0001).

CONCLUSIONS

In patients with STEMI undergoing primary percutaneous coronary intervention, implantation of PES as compared with BMS significantly reduces neointimal hyperplasia but results in higher rates of uncovered and malapposed stent struts as assessed by optical coherence tomography at 13-month follow-up. Further studies are required to determine the clinical significance of these findings.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00433966.

Optical coherence tomography in ST-elevation myocardial infarction treated with novel drug-eluting stent: preprocedural, postimplant and 2-month follow-up findings

The use of drug-eluting stents (DES) allowed the reduction in the need for repeat revascularization. At the culprit site in acute myocardial infarction patients treated with first-generation DES, the interaction between the eluted drug and the underlying necrotic core may generate different patterns of pathologic vessel response and delayed healing. A new generation DES intrepide elutes trapidil. Its modes of action are neither cytotoxic nor cytostatic, and may promote normal re-endothelialization. Due to its high resolution, optical coherence tomography (OCT) allows accurate detection of thrombus deposition and stent strut coverage at follow-up. Intravascular ultrasound (IVUS) has enhanced tissue penetration and provides information on vessel remodeling. Using OCT and IVUS, we evaluated the intravascular morphology of the culprit vessel, the acute and intermediate result of novel DES implanted to treat an ST-segment elevation myocardial infarction.

Strut coverage and vessel wall response to zotarolimus-eluting and bare-metal stents implanted in patients with ST-segment elevation myocardial infarction: the OCTAMI (Optical Coherence Tomography in Acute Myocardial Infarction) Study

OBJECTIVES

Using optical coherence tomography, we assessed the proportion of uncovered struts at 6-month follow-up in zotarolimus-eluting stents (ZES), specifically Endeavor (Medtronic CardioVascular, Santa Rosa, California) stents, and identical bare-metal stents (BMS) implanted in patients with ST-segment elevation myocardial infarction (STEMI).

BACKGROUND

Sirolimus- and paclitaxel-eluting stents implanted in STEMI have been associated with delayed healing and incomplete strut coverage. ZES are associated with a more complete and uniform strut coverage in stable patients, but whether this holds true also after STEMI is unknown.

METHODS

Forty-four patients with STEMI who underwent primary PCI were randomized to ZES or BMS (3:1 randomization). Angiographic, intravascular ultrasound, and optical coherence tomography follow-up was conducted at 6 months and clinical follow-up at 1 year. All images were analyzed by an independent core laboratory that was blind to stent assignments.

RESULTS

There were no differences between ZES and BMS in percentage of uncovered struts (median: 0.00% [interquartile range (IQR): 0.00% to 1.78%] vs. 1.98% [IQR: 0.21% to 7.33%], p = 0.13), maximum length of uncovered segments (0.00 [IQR: 0.00 to 1.19] mm vs. 1.38 [IQR: 0.65 to 3.30] mm, p = 0.10), percentage of malapposed struts (0.00% [IQR: 0.00% to 0.23%] vs. 0.15% [IQR: 0.00% to 5.81%], p = 0.16), and maximum length of malapposed segments (0.00 [IQR: 0.00 to 0.67] mm vs. 0.33 [IQR: 0.00 to 2.55] mm, p = 0.20). Neointimal response was similar between ZES and BMS (332 [IQR: 240 to 429] microm vs. 186 [IQR: 136 to 348] microm, p = 0.99) and evenly distributed. No late acquired malapposition was observed in both groups. There were no deaths, myocardial infarction, or stent thromboses at 1 year.

CONCLUSIONS

This optical coherence tomography study found no difference in strut coverage and similar vessel response to ZES, when compared with identical BMS, implanted during primary percutaneous coronary intervention in STEMI patients. (Six-Month Coverage and Vessel Wall Response of the Zotarolimus Drug-Eluting Stent Implanted in AMI Assessed by Optical Coherence Tomography [OCTAMI]; NCT00704561).

Optical coherence tomography assessment of in vivo vascular response after implantation of overlapping bare-metal and drug-eluting stents

OBJECTIVES

We designed a randomized trial exploiting optical coherence tomography (OCT) to assess coverage and apposition of overlapping bare-metal stents (BMS) and drug-eluting stents (DES) in human coronary arteries.

BACKGROUND

Overlapping DES impair healing in animals. Optical coherence tomography allows accurate in vivo assessment of stent strut coverage and apposition.

METHODS

Seventy-seven patients with long coronary stenoses were randomized to overlapping sirolimus-eluting stents (SES), paclitaxel-eluting stents (PES), zotarolimus-eluting stents (ZES), or BMS. The primary goal of the study was to determine the rate of uncovered/malapposed struts in overlap versus nonoverlap segments, according to stent type, at 6-month follow-up with OCT.

RESULTS

A total of 53,047 struts were analyzed. The rate of uncovered/malapposed struts was 1.5 +/- 3.4% and 0.6 +/- 2.7% in overlap versus nonoverlap BMS (p = NS), respectively, and 4.3 +/- 11% and 3.6 +/- 8% in overlap versus nonoverlap DES (p = NS), respectively. There were no differences in the rates of uncovered/malapposed struts between overlapping BMS and DES, likely due to low frequency of uncovered/malapposed struts in ZES (0.1 +/- 0.4%), which offset the higher rates observed in SES (6.7 +/- 9.6%) and PES (6.7 +/- 16.5%, p < 0.05). Overlap segments showed greater neointimal volume obstruction versus nonoverlap segments in all DES (p < 0.05 for all DES types). Strut-level neointimal thickness at overlap and nonoverlap segments were lowest in SES (0.16 +/- 0.1 mm and 0.12 +/- 0.1 mm, respectively) compared with PES (0.27 +/- 0.1 mm and 0.20 +/- 0.1 mm, respectively), ZES (0.40 +/- 0.16 mm and 0.33 +/- 0.13 mm, respectively), and BMS (0.55 +/- 0.31 mm and 0.53 +/- 0.25 mm, respectively, p < 0.05).

CONCLUSIONS

As assessed by OCT the impact of DES on vascular healing was similar at overlapping and nonoverlapping sites. However, strut malapposition, coverage pattern, and neointimal hyperplasia differ significantly according to DES type. (Optical Coherence Tomography for Drug Eluting Stent Safety [ODESSA]; NCT00693030).

Strut Coverage and Vessel Wall Response to a New-Generation Paclitaxel-Eluting Stent With an Ultrathin Biodegradable Abluminal Polymer

Background—

Polymer-coated drug-eluting stents are effective in preventing restenosis but have been associated with delayed healing and incomplete strut coverage. It is unknown whether paclitaxel-eluting stents (PES) with minimal biodegradable abluminal coating enhances strut coverage while preventing neointimal hyperplasia. Using optical coherence tomography (OCT) as a primary imaging modality, we assessed the proportion of uncovered struts at 6-month follow-up in PES coated with durable versus ultrathin (<1 μm) biodegradable abluminal polymers.

Methods and Results—

In this pilot trial, 60 patients with de novo lesions (≤25 mm) in native coronary vessels were randomly assigned to receive either TAXUS Liberté PES or JACTAX PES, a Liberté stent with polymer deposited abluminally as microdots (JACTAX HD: 9.2 μg each of polymer and paclitaxel per 16-mm stent; JACTAX LD: 5 μg each). OCT follow-up occurred at 6 months with clinical follow-up through 1 year. The primary end point was percent uncovered struts by OCT. An independent core laboratory blinded to stent assignment analyzed images. The 6-month rate of uncovered struts per patient was 5.3±14.7% for TAXUS Liberté, 7.0±12.2% for JACTAX HD, and 4.6±7.3% for JACTAX LD ( P =0.81); percent malapposed struts was 1.4±4.4%, 0.8±1.9%, and 1.1±2.8%, respectively ( P =0.86). Strut-level intimal thickness was 0.20±0.10, 0.22±0.15, and 0.24±0.15 mm ( P =0.64); percent volume obstruction by OCT was 22.2±12.8, 22.5±16.2, and 25.8±15.2 ( P =0.69). There were no deaths, Q-wave myocardial infarctions, or stent thromboses through 1 year.

Conclusions—

JACTAX PES with an ultrathin microdot biodegradable abluminal polymer did not result in improved strut coverage at 6 months compared with TAXUS Liberté.

Clinical Trial Registration—

URL: http://www.clinicaltrials.gov . Unique identifier: NCT00776204.

Optical coherence tomography (OCT) strut-level analysis of drug-eluting stents (DES) in human coronary bifurcations

AIMS

We sought to evaluate the vascular response of stent struts deployed in bifurcation segments using optical coherence tomography (OCT).

METHODS AND RESULTS

This study is a sub-analysis of ODESSA, a prospective randomised trial designed to evaluate healing of overlapped drug-eluting stents (DES) vs. bare metal stents (BMS) (sirolimus SES: paclitaxel PES: zotarolimus ZES: Liberté BMS in a 2: 2: 2: 1 ratio) for de novo coronary artery stenosis. OCT was performed at 6-month follow-up. Bifurcation segments with side branch diameters larger than 1.5mm by angiography were analysed. The cross-sectional image at the bifurcation segment was divided into three regions: opposite to the ostium (OO), adjacent to the ostium (AO), or side-branch ostium (SO). Struts were classified in three categories: uncovered (U), covered (C), or proliferative (P). The incidence of each strut category was compared between regions and stent types. There were 12,656 struts in 61 bifurcation segments (PES: 16, SES: 14, ZES: 23, Liberté BMS: 8) from 46 patients obtained at six months. PES had the highest rate of U in SO region (PES 60.1, SES 17.0, ZES 13.2, BMS 12.3 (%), P<0.0001), whereas SES demonstrated the highest rate of U in OO (PES 3.8, SES 14.0, ZES 1.5, BMS 0.0 (%), P=0.0025).

CONCLUSIONS

This study demonstrates a variable pattern of strut coverage in the bifurcation among stent technologies, with a high percentage of PES floating struts remaining uncovered at 6-month follow-up.

Long-term outcomes in patients undergoing coronary stenting on dual oral antiplatelet treatment requiring oral anticoagulant therapy

In patients undergoing coronary stenting, long-term dual antiplatelet therapy with aspirin and clopidogrel reduces atherothrombotic events but also increases the risk of bleeding. The potential for developing bleeding complications is further enhanced in patients also requiring oral anticoagulant treatment ("triple therapy"). The aim of the study is to assess long-term outcomes associated with the use of triple-therapy in patients undergoing coronary stenting and evaluate how these may be affected by targeting international normalized ratio (INR) values to the lower therapeutic range. We prospectively studied 102 consecutive patients undergoing coronary stenting treated with dual antiplatelet therapy also requiring oral anticoagulation. INR was targeted to the lower therapeutic range (2.0 to 2.5). Patients requiring oral anticoagulant therapy because of mechanical valve prosthesis were excluded. Patients were followed for 18 months, and bleeding, defined according to Thrombolysis in Myocardial Infarction criteria, and major adverse cardiac events were recorded. Outcomes were compared with a control group (n = 102) treated only with dual antiplatelet therapy. The mean duration of triple therapy was 157 +/- 134 days. At 18 months, a nonsignificant increase in bleeding was observed in the triple versus dual therapy group (10.8% vs 4.9%, p = 0.1). INR values were higher in patients with bleeding (2.8 +/- 1.1 vs 2.3 +/- 0.2, p = 0.0001). In patients who had INR values within the recommended target (79.4%), the risk of bleeding was significantly lower compared with patients who did not (4.9 vs 33%, p = 0.00019) and with that observed in the control group (4.9%). An INR >2.6 was the only independent predictor of bleeding. There were no significant differences in major adverse cardiac events between groups (5.8% vs 4.9%, p = 0.7). In conclusion, in patients undergoing coronary stenting on triple therapy, targeting lower therapeutic INR values reduces the risk of bleeding complications.