Percutaneous Coronary Intervention for Coronary Ostial Lesions: Now and Then

Ostial coronary artery disease, defined as a coronary stenosis within 3 mm from the vessel origin, is not an uncommon angiographic finding. Ostial stenoses can be divided into aorto-ostial or side branch ostial diseases. Ostial coronary disease is typically diagnosed by invasive or CT coronary angiography. Given their peculiar anatomical location, it is not uncommon for ostial lesions to go unnoticed without meticulous angiographic assessment, and multiple angiographic projections may be needed for their adequate identification. Thus, an optimal coronary angiography procedure should include a minimum number of – sometimes orthogonal – projections to unmask “hidden” or “ambiguous” lesions. Pressure dampening can be the only sign of a tight aorto-ostial stenosis. Other indirect evidence of a tight ostium is the absence of backflush of contrast. Intravascular ultrasound (IVUS) or invasive physiological assessment – on top of visual angiographic assessment – are important diagnostic modalities when uncertainty exists about the diagnosis or severity of ostial lesions. Determining plaque composition and its extension by IVUS is important prior to intervention. On the other hand, the use of optical coherence tomography (OCT) for aorto-ostial lesions are usually discouraged given the need for bloodless field for adequate imaging which is unachievable in aorto-ostial positions 1.When evaluating the severity of ostial stenosis, fractional flow reserve (FFR) can play an important role. Koo et al. 2 investigated the incremental value of FFR, on top of angiographic assessment, in evaluating ostial diseases of side branches after main vessel stenting. No lesions with <75% stenosis severity by angiography were functionally significant by FFR while only 20 out of 73 lesions with ≥75% stenosis visually proved to be functionally significant 2. In general, coronary physiological assessment in the catheterization laboratory – most traditionally by FFR – is indispensable, especially for ostial stenoses 3. One study found that angiographic assessment and IVUS were suboptimal to detect functionally significant ostial stenoses involving smaller side branches as opposed to main vessel ostial stenosis 4. In aorto-ostial stenoses, intravenous adenosine must be used rather than intracoronary adenosine boluses.Percutaneous coronary intervention (PCI) for ostial coronary disease has been always a challenge with worse outcomes observed when compared to nonostial disease. Higher incidence of restenosis was observed in ostial disease, especially in the era of balloon angioplasty 5. Procedural outcomes and instent restenosis improved with the advent of bare metal stents but were still suboptimal when compared to nonostial disease 6. Similar trends were observed with first-generation drug-eluting stents (DESs) 7. Newer generation DESs, however, performed better when compared to their earlier generation counterparts with significantly lower long-term adverse events 8. The suboptimal PCI outcome was generally believed to be due to the technical difficulties (e.g., difficulty positioning stents to adequately cover the ostium without excessive protrusion of the stent in the parent vessel/aorta or missing the ostium altogether). One study showed the incidence of stent misplacement to be as high as 54% when dealing with ostial stenoses. Proximal stent misplacement (in aorto-ostial disease) can lead to higher failure rates of coaxial guide re-engagement, while distal stent misplacement was associated with increased need for additional stents implantation. Both scenarios were associated with poor long-term outcomes with higher incidence of repeat revascularization due to instent restenosis 9. Notably, primary PCI involving ostial LAD intervention was shown to be associated with higher mortality when compared to nonostial disease of the LAD 10. Various stent placement techniques have been developed to optimize ostial stent positioning. Most commonly, thefloating wire technique described in aorto-ostial disease has been widely used and is associated with better outcomes 11. The anchor wire or stent tail wire technique (also known as Szabo technique) is another technique that suits all types of ostial lesions (aorto-ostial and branch ostial stenoses); it was first described in 2005 and entails using a second guide wire that is either placed in the aorta (in aorto-ostial lesions) or the nonstenotic branch (in dealing with side branch ostial stenoses). After loading the stent balloon on the first wire, the proximal end of the second wire is then threaded through the proximal stent strut cell with care to avoid injuring the stent balloon. The stent is then advanced on both wires and delivered to the target lesion; the stent is advanced until the second wire prevents any further advancement which demarcates that the proximal stent strut is just proximal to the ostium 12.A retrospective study, that compared the angiographic outcomes in aorto-ostial stenting and bifurcation Medina 0,1,0 lesions using the Szabo technique versus conventional angiographic guided method, reported significantly lower rates of stent malpositioning with the anchor wire technique (6.4% vs. 41%) but no difference in MACEs at 30 days 13. Several limitations and technical tips should be considered when using the Szabo technique 14. Other technologies (e.g., Ostial Pro device, dedicated ostial stents) and techniques (e.g., TAP) have been developed in the pursuit of perfection in stent positioning for ostial lesions. The added benefit of such new techniques/technologies on top of conventional methods remains uncertain. Utilizing IVUS to guide ostial interventions can be potentially helpful for PCI optimization and has been shown to improve long-term clinical outcomes 15. Other technologies for debulking ostial plaques and preparing lesions for proper stent delivery have been used, especially rotational atherectomy 16 and excimer laser 17.Ostial LM disease represents a particular therapeutic challenge. Based on the revascularization guidelines, surgical intervention is recommended to improve survival compared to medical treatment. However, the emergence of a plethora of data – starting with Syntax trial – showed that unprotected LM PCI has become a reasonable therapeutic alternative, with improved survival as opposed to medical treatment 18, and comparable outcomes to bypass surgery up to 5 years of follow-up as shown in the MAIN-COMPARE registry 19. This is true for patients with low Syntax score, inclusive of those with isolated ostial or mid-shaft left main disease. The guidelines emphasize the value of using a heart team approach in patients with complex CAD and LM disease 1. Percutaneous intervention on ostial RCA disease poses significant challenges since the inception of PCI and was historically associated with a high incidence of abrupt vessel occlusion and restenosis rates 20. Coronary stents, especially the newer DESs, in addition to stent optimization techniques and lesion preparation all helped improve PCI outcomes of ostial RCA lesions 21. Ostial large branch vessels (LAD and LCX) are technically left main bifurcational lesions. Outcomes of PCI for LM bifurcation are consistently inferior to isolated ostial LM PCI (mainly due to TVR) as shown in the Delta Registry 22. On the other hand, medical treatment of isolated diagonal ostial stenoses had comparable mortality and rates of MI when compared to PCI and was even associated with lower rates of rehospitalization, severe angina, and repeat revascularization 23. Overall, few interventions helped improve outcomes of PCIs for coronary ostial lesions, namely DESs, IVUS use, and the implementation of certain stent placement techniques.The above serves as succinct overview of ostial coronary disease and its percutaneous management, and it is in this context that the study conducted by Zornitzki and colleagues should be viewed. Zornitzki et al. provide an additional insight on a category of coronary lesions that are largely under-represented in clinical trials. In this nonrandomized trial, the authors presented their real-life experience using the latest generation DES and involving a variety of patients’ presentations, ranging from stable coronary artery disease up to acute STEMI. LM aorto-ostial stenoses were appropriately excluded. Zornitzki L et al. showed no significant outcomes differences when comparing ostial to nonostial proximal lesions. TVR (the primary endpoint), TLR, and MACE rates were statistically not different between groups. Despite being a small single-center study, it still can shed some light on the impact of current outcomes among coronary ostial PCI given its contemporary nature and the use of latest advances in stent technology. The study has, however, many limitations. IVUS use was relatively low, though it was significantly used more in ostial lesions (12% vs. 2.5%). The study also lacked granularity on procedural details, operators’ expertise, and adjunctive pharmacotherapies. Notwithstanding these limitations, the study by Zornitzki and colleagues is a welcome addition to the literature and calls for larger prospective studies to provide more definitive guidance for clinical practice.Authors of this manuscript have no conflict of interest to disclose.No direct funding was provided for the current article. Furthermore, no funding was received by the authors in research relevant to the current article.Mohammed Saleh: had a substantial involvement in conception and the design of the current manuscript, literature search, laying out the structure of the article, and reviewing intellectual concepts related to the manuscript. His work also included revising the manuscript and ensuring it served the very purpose it was intended for. Hani Jneid: played a substantial role in initiating, writing, drafting and revising, and final approval of the manuscript. Dr. Jneid was also involved in reviewing the literature relevant to the current article and updating the intellectual concepts to match to most recent available evidence.