OCT-Guided PCI: Are We There Yet?

Using near-infrared light technology, optical coherence tomography (OCT) today offers excellent in vivo intravascular imaging of the vessel wall with a unique axial resolution of 10-15 µm. In this month’s Journal of Invasive Cardiology, Agrawal et al present a retrospective cohort of patients who were evaluated with intravascular OCT imaging after stent placement as part of a quality improvement project.¹ Initial studies on OCT compared with intravascular ultrasound (IVUS) after stent placement suggested that OCT was inferior to IVUS in such patients because OCT guidance was associated with smaller stent expansion measurements and more frequent significant residual reference segment stenosis compared with conventional IVUS guidance.² However, the 670-patient CLI-OPCI trial demonstrated a significantly lower 1-year risk of cardiac death (1.2% vs 4.5%; P=.01), cardiac death, or myocardial infarction (MI; 6.6% vs 13.0%; P=.01), and the composite of cardiac death, MI, or repeat revascularization (9.6% vs 14.8%; P=.04) with OCT-guided percutaneous coronary intervention (PCI) compared with PCI alone even after extensive multivariable analysis and propensity-score adjusted analyses for baseline and procedural differences (odds ratio, 0.49 [95% confidence interval, 0.25-0.96]; P=.04).³ OCT offers an excellent evaluation of the vascular intima, providing accurate identification of thrombus, stent apposition, edge dissection, and tissue protrusion. 

Due to its excellent axial resolution, OCT often reveals “imperfect” PCI outcomes (90% in this study). Serial OCT evaluation post PCI has shown that >70% of malapposed stents resolve with time, especially when stent-vessel distance is ≤260 µm, while most cases of thrombus, tissue prolapse, and minor stent edge dissection ultimately resolve.⁴ Another study by Raber et al showed that stent edge dissections <3 mm in longitudinal views and stent malapposition <270 µm do not increase the risk of stent thrombosis.⁵ 

OCT after late stent thrombosis (LST) showed an increased frequency and length of uncovered and malapposed stent struts, as well as positive remodeling.⁶ The presence of >30% uncovered struts was highly predictive of stent thrombosis. OCT after very late stent thrombosis (VLST) identified malapposition, neoatherosclerosis, uncovered struts, and stent underexpansion as the main causes in descending order.⁷ Serial OCT imaging after PCI with drug-eluting stent (DES) implantation demonstrated that the percentage of uncovered and malapposed stent struts progressively decreased at 6-month and 12-month follow-up; however, complete coverage was rare.⁸ Neointimal growth can continue as long as 48 months after DES implantation.⁹ Another multicenter registry suggested that smaller lumen cross-sectional area and neointimal morphology was associated with intrastent thrombosis.¹⁰ Patients with ST-elevation MI appear to have higher rates of stent malapposition and incomplete coverage after DES placement compared with patients treated for stable or unstable angina, as well as patients with chronic total occlusion interventions.^11,12

OCT has emerged an important imaging tool in the armamentarium of the interventional cardiologist. It has assisted in our understanding of atherosclerosis progression after stent placement and in identifying the causes of PCI adverse outcomes. However, few studies have been completed on the importance of immediate OCT findings after PCI with clinical outcomes. With the existing data, we know that optimal stent expansion should be attempted with stent apposition ≤260 µm and edge dissections >3 mm should be optimally covered. However, it is unclear whether further stent optimization may allow faster neointimal coverage or alter positive remodeling, which may result in decreased rates of LST or VLST.      

References

1.    Agrawal M, Hakeem A, Ahmed Z, Uretsky BF. Utility of frequency domain optical coherence tomographic evaluation of angiographically optimized stented lesions. J Invasive Cardiol. 2016;28:94-97.

2.    Habara M, Nasu K, Terashima M, et al. Impact of frequency-domain optical coherence tomography guidance for optimal coronary stent implantation in comparison with intravascular ultrasound guidance. Circ Cardiovasc Interv. 2012;5:193-201. Epub 2012 Mar 27.

3.    Prati F, Di Vito L, Biondi-Zoccai G, et al. Angiography alone versus angiography plus optical coherence tomography to guide decision-making during percutaneous coronary intervention: the Centro per la Lotta contro l’Infarto-Optimisation of Percutaneous Coronary Intervention (CLI-OPCI) study. EuroIntervention. 2012;8:823-829. 

4.    Kawamori H, Shite J, Shinke T, et al. Natural consequence of post-intervention stent malapposition, thrombus, tissue prolapse, and dissection assessed by optical coherence tomography at mid-term follow-up. Eur Heart J Cardiovasc Imag. 2013;14:865-875. 

5.    Räber L, Radu MD. Optimising cardiovascular outcomes using optical coherence tomography-guided percutaneous coronary interventions. EuroIntervention. 2012;8:765-771.

6.    Guagliumi G, Sirbu V, Musumeci G, et al. Examination of the in vivo mechanisms of late drug-eluting stent thrombosis: findings from optical coherence tomography and intravascular ultrasound imaging. JACC Cardiovasc Interv. 2012;5:12-20. 

7.    Taniwaki M, Radu MD, Zaugg S, et al. Mechanisms of very late drug-eluting stent thrombosis assessed by optical coherence tomography. Circulation. 2016 Jan 13 (Epub ahead of print).

8.    Katoh H, Shite J, Shinke T, et al. Delayed neointimalization on sirolimus-eluting stents: 6-month and 12-month follow-up by optical coherence tomography. Circ J. 2009;73:1033-1037. Epub 2009 Apr 14.

9.    Li S, Gai L, Yang T, et al. Evaluation of long-term follow-up with neointimal coverage and stent apposition after sirolimus-eluting stent implantation by optical coherence tomography. Catheter Cardiovasc Interv. 2013;81:768-775. Epub 2012 Jul 23.

10.    Gao L, Lee S, Kim CJ, et al. Incidence and morphological predictors of Intrastent coronary thrombus after drug-eluting stent implantation (from a Multicenter Registry). Am J Cardiol. 2016;117:369-375. Epub 2015 Nov 18.

11.    Gonzalo N, Barlis P, Serruys PW, et al. Incomplete stent apposition and delayed tissue coverage are more frequent in drug-eluting stents implanted during primary percutaneous coronary intervention for ST-segment elevation myocardial infarction than in drug-eluting stents implanted for stable/unstable angina: insights from optical coherence tomography. JACC Cardiovasc Interv. 2009;2:445-452.

12.    Heeger CH, Busjahn A, Hildebrand L, et al. Delayed coverage of drug-eluting stents after interventional revascularisation of chronic total occlusions assessed by optical coherence tomography: the ALSTER-OCT-CTO registry. EuroIntervention. 2016;11:1004-1012.

____________________________________________

From the ¹Citizens Memorial Heart and Vascular Institute, Bolivar, Missouri/University of Missouri, Columbia, Missouri; and ²Arkansas Heart Hospital, Little Rock, Arkansas/Koc University, School of Medicine, Istanbul, Turkey.

Disclosure: The authors have completed and returned the ICMJE Form for Disclosure of Potential Conflicts of Interest. None were reported.

Address for correspondence: Konstantinos Marmagkiolis, MD, MBA, FACC, FSCAI, 1500 N Oakland Road, Bolivar MO 65613. Email: c.marmagiolis@gmail.com