Clinical Implications of "Tailored" Antiplatelet Therapy in Patients With Chronic Total Occlusion

Coronary bypass surgery for multivessel disease after percutaneous coronary intervention in acute coronary syndromes: why, for whom, how early?

Multivessel coronary artery disease is present in ∼50% of patients with acute coronary syndrome and, compared with single-vessel disease, entails a higher risk of new ischaemic events and a worse prognosis. Randomized controlled trials have shown the superiority of 'complete revascularization' over culprit lesion-only treatment. Trials, however, only included patients treated with percutaneous coronary intervention (PCI), and evidence regarding complete revascularization with coronary artery bypass graft (CABG) surgery after culprit lesion-only PCI ('hybrid revascularization') is lacking. The CABG after PCI is an open, non-negligible therapeutic option, for patients with non-culprit left main and/or left anterior descending coronary artery disease where evidence in chronic coronary syndrome patients points in several cases to a preference of CABG over PCI. This valuable but poorly studied 'PCI first-CABG later' option presents, however, relevant challenges, mostly in the need of interrupting post-stenting dual antiplatelet therapy (DAPT) for surgery to prevent excess bleeding. Depending on patients' clinical characteristics and coronary anatomical features, either deferring surgery after a safe interruption of DAPT or bridging DAPT interruption with intravenous short-acting antithrombotic agents appears to be a suitable option. Off-pump minimally invasive surgical revascularization, associated with less operative bleeding than open-chest surgery, may be an adjunctive strategy when revascularization cannot be safely deferred and DAPT is not interrupted. Here, the rationale, patient selection, optimal timing, and adjunctive strategies are reviewed for an ideal approach to hybrid revascularization in post-acute coronary syndrome patients to support physicians' choices in a case-by-case patient-tailored approach.

Evaluation of an automated platelet aggregation method for detection of congenital or acquired platelet function defects

BACKGROUND

Light transmission aggregometry (LTA) is the most widely used laboratory method for an initial screening of patients with a suspected platelet function defect (PFD), and its use has also been proposed for assessing the efficacy of antiplatelet treatment (APT). An automated LTA method has been developed by Sysmex (Kobe, Japan) on a routine coagulation analyzer (CS-2400), together with a new research parameter called PAL (platelet aggregation level) to evaluate patients on APT.

MATERIALS AND METHODS

We evaluated the performance of CS-2400 compared to a stand-alone lumi-dual-aggregometer device in the diagnosis of PFD and in assessing the efficacy of APT. For these purposes, the study population was represented by a cohort of 23 patients with a previous diagnosis of PFD and a cohort of 28 patients on APT.

RESULTS

Compared to healthy volunteers, patients with PFD showed a statistically significant reduction (p<0.05) in the maximal %light transmission, irrespective of the agonist used, both with the CS-2400 and the lumi-dual-aggregometer. As regards PFD patients, CS-2400 was effective in identifying the more severe defects, with a good sensibility and specificity, but less effective in identifying milder forms of PFD, such as platelet secretion defects. Patients on APT showed a statistically significant (p=0.001) reduced median %light transmission and PAL scores compared to healthy controls.

DISCUSSION

Thanks to this LTA technology, CS-2400, a routine coagulation analyzer widely available in routine laboratories, could prove useful for initial assessment of patients with a suspected PFD. Moreover, the PAL scores were a fairly accurate reflection of the platelet response to APT.

Flow-chamber device (T-TAS) to diagnose patients suspected of platelet function defects

BACKGROUND

Patients suspected of platelet function defects represent a diagnostic challenge for the clinical laboratory, mainly due to the complexity and poor standardization of screening methods. We compared a new flow-based chip-equipped point-of-care (T-TAS) device with lumi-aggregometry and other specific tests.

MATERIALS AND METHODS

The study included 96 patients suspected of platelet function defects and 26 patients referred to hospital for an evaluation of residual platelet function while on antiplatelet therapy.

RESULTS

Forty-eight of 96 patients displayed abnormal platelet function by lumi-aggregometry, and 10 of them had defective granule content and were classified as δ-storage pool disease (δ-SPD). T-TAS compared favorably with lumi-aggregometry in detecting the most severe forms of platelet function defects (i.e., δ-SPD) [test agreement (lumi-light transmission aggregometry [lumi-LTA] vs T-TAS) for the δ-SPD subgroup was 80% and K CHOEN 0.695. T-TAS was less sensitive to milder platelet function defects (i.e., primary secretion defects [PSD]). Concerning patients on antiplatelets, test agreement (lumi-LTA vs T-TAS) in detecting patients who were responders to this therapy was 54%; K CHOEN 0.150.

DISCUSSION

The results indicate that T-TAS can detect the more severe forms of platelet function defects such as δ-SPD. There is limited agreement of T-TAS with lumi-aggregometry in identifying responders to antiplatelets. However, this poor agreement is commonly shared by lumi-aggregometry and other devices owing to the lack of test specificity and of prospective data from clinical trials linking platelet function with therapeutic efficacy.

Recanalisation of coronary chronic total occlusions

Percutaneous treatment of coronary chronic total occlusions (CTO) has advanced greatly since its advent in the late 1970s through the development of dedicated wires and microcatheters, the improved skills of highly experienced operators and the adoption of new sophisticated strategies to guide procedural planning. The contemporary procedural success rate is 80-90% with a reduction in complications. Although there has been no improvement in prognosis in randomised trials to date, they, and other controlled registries of thousands of patients, confirm the pivotal role of CTO recanalisation in the treatment of angina and dyspnoea and an improvement in quality of life. Despite this evidence, CTO recanalisation is grossly underutilised. This review reports a detailed overview of the history, indications and treatment strategies for CTO recanalisation and hopes to increase interest among new, and especially young, operators in this demanding, rapidly evolving field of interventional cardiology.

Assessing the Clinical Influence of Chronic Total Occlusions (CTOs) Revascularization and the Impact of Vascularization Completeness on Patients with Left Ventricular (LV) Systolic Dysfunction

Objectives

This paper intends to assess the clinical influence of chronic total occlusions (CTOs), revascularization, and the impact of vascularization completeness on patients with left ventricular (LV) systolic dysfunction.

Background

The roles of CTO vascularization in clinical benefits remain conflicting. In addition, data concerning the different results of CTO vascularization and vascularization completeness according to LV systole function were assessed.

Methods

From an overall 918 consecutive patients with at least one CTO, 281 patients with ejection fraction (EF) ≤40% accepted coronary angiographic analysis between Jan 1, 2012, and Dec 31, 2020, and 29 patients were excluded. Subsequently, 261 patients were grouped into the successful CTO-PCI revascularization group (SCR, n = 135) and the optimal medical therapy group (OMT, n = 126). The prognosis influence of successfully finished CTO-PCI and complete revascularization on survival was evaluated. The primary endpoint was cardiac mortality, and the secondary endpoints were major adverse cardiac and cerebrovascular events (MACCE).

Results

After a median follow-up time of 38.02 months, the cardiac mortality (p=0.037) and MACCE (p=0.001) were more remarkable in the OMT group than in the SCR group. Moreover, patients with CTO-PCI had survival benefits from complete revascularization for MACCE (p=0.025) and cardiac mortality (p=0.041). Based on multivariable Cox proportional hazards regression analysis, age ≧ 75 years (HR: 3.443, 95% CI 1.719–6.897, p < 0.001) predicted a worse probability of cardiac mortality. Additionally, previous PCI (HR: 1.592, 95% CI 1.034–2.449, p=0.035) and previous MI (HR: 1.971, 95% CI 1.258–3.088, p=0.003) predicted a worse probability of MACCE, and SCR (HR: 0.499, 95% CI 0.320–0.776, p=0.002) was a protection predictor of MACCE.

Conclusion

In patients with LV systole dysfunction (EF ≤ 40%), successfully finished CTO-PCI is related to long-term survival benefits. The benefits were more remarkable in patients with complete coronary revascularization (CCR).

Chronic total occlusion revascularization: A complex piece to "complete" the puzzle

Treatment of coronary chronic total occlusion (CTO) with percutaneous coronary intervention (PCI) has rapidly increased during the past decades. Different strategies and approach were developed in the recent past years leading to an increase in CTO-PCI procedural success. The goal to achieve an extended revascularization with a high rate of completeness is now supported by strong scientific evidences and consequently, has led to an exponential increase in the number of CTO-PCI procedures, even if are still underutilized. It has been widely demonstrated that complete coronary revascularization, achieved by either coronary artery bypass graft or PCI, is associated with prognostic improvement, in terms of increased survival and reduction of major adverse cardiovascular events. The application of “contemporary” strategies aimed to obtain a state-of-the-art revascularization by PCI allows to achieve long-term clinical benefit, even in high-risk patients or complex coronary anatomy with CTO. The increasing success of CTO-PCI, allowing a complete or reasonable incomplete coronary revascularization, is enabling to overcome the last great challenge of interventional cardiology, adding a “complex” piece to “complete” the puzzle.

Walking the Line with Ticagrelor: Meta-Analysis Comparing the Safety and Efficacy of Ticagrelor Monotherapy after a Short Course of Ticagrelor-Based Dual Antiplatelet Therapy versus Standard Therapy in Complex Percutaneous Coronary Intervention

(1) Shorter-duration dual antiplatelet therapy (DAPT) followed by single antiplatelet therapy has been shown to significantly reduce bleeding events while preserving anti-ischemic effects in patients undergoing conventional percutaneous coronary interventions (PCI). Whether this strategy is also safe and effective in complex PCI remains elusive; (2) A systematic search of randomized controlled trials comparing a short course of ticagrelor-based DAPT versus standard DAPT in patients undergoing complex PCI was performed; (3) Of 10,689 studies screened, 3 were identified for a total of 4176 participants on ticagrelor monotherapy after a short course of ticagrelor-based DAPT, and 4209 on standard DAPT. The pooled analysis revealed no difference in the outcomes of major bleeding, myocardial infarction, definite or probable stent thrombosis and ischemic stroke. A significant reduction in the risk of cardiovascular death (incidence rate ratio (IRR) 0.52; 95% CI 0.28–0.96; p = 0.04), all-cause death (IRR 0.65; 95% CI 0.49–0.86; p = 0.003), and any bleeding events (IRR 0.62; 95% CI 0.47–0.81; p < 0.001) was seen in the shorter DAPT group; (4) Among patients undergoing complex PCI, ticagrelor monotherapy after a short course of ticagrelor-based DAPT significantly reduced bleeding risk without increasing ischemic risk. More data are needed to definitively explain mortality benefits.

Platelet Function Testing and Genotyping for Tailoring Treatment in Complex PCI Patients

Dual antiplatelet therapy (DAPT), comprising aspirin and a P2Y12 receptor inhibitor, is considered the cornerstone of treatment in patients who have undergone percutaneous coronary intervention (PCI). Patients with complex PCI (C-PCI) constitute a special PCI subpopulation, characterized by increased ischemic risk. Identifying the optimal DAPT strategy is often challenging and remains controversial in this setting. In an attempt to balance ischemic and bleeding risks in C-PCI patients receiving DAPT, treatment individualization regarding potency and duration has evolved as a feasible approach. Platelet function testing and genotyping have been evaluated in several trials with conflicting and mostly neutral results. The aim of this review is to critically appreciate the role of these tools for antiplatelet treatment tailoring specifically in C-PCI patients. Because existing evidence is limited, dedicated future studies are warranted to elucidate the utility of platelet function testing and genotyping in C-PCI.

Antithrombotic Therapy in Chronic Total Occlusion Interventions

Chronic total occlusion (CTO) recanalization is among the most complex subsets of coronary interventions. Hence, optimum peri- and post-procedural anticoagulation and antiplatelet therapy is key for the achievement of successful revascularization and reduction of major adverse cardiovascular outcomes in patients undergoing CTO percutaneous coronary intervention (PCI). Unfractionated heparin is still considered the gold standard anticoagulant because its action can be reversed by protamine administration, with bivalirudin being reserved mainly for patients with heparin-induced thrombocytopenia. However, small studies comparing unfractionated heparin with bivalirudin in CTO interventions have shown similar outcomes. Glycoprotein IIb/IIIa inhibitors should, in general, be avoided. Aspirin in combination with clopidogrel for 6–12 months is the standard post CTO PCI dual antiplatelet regimen. For the most complex cases, clopidogrel can be substituted by a more potent P2Y12 inhibitor, namely ticagrelor or prasugrel.

Factors Influencing Stent Failure in Chronic Total Occlusion Coronary Intervention

Stent failure remains one of the greatest challenges for interventional cardiologists. Despite the evolution to superior second- and third-generation drug-eluting stent designs, increasing use of intracoronary imaging and the adoption of more potent antiplatelet regimens, registries continue to demonstrate a prevalence of stent failure or target lesion revascularisation of 15-20%. Predisposition to stent failure is consistent across both chronic total occlusion (CTO) and non-CTO populations and includes patient-, lesion- and procedure-related factors. However, histological and pathophysiological properties specific to CTOs, alongside complex strategies to treat these lesions, may potentially render percutaneous coronary interventions in this cohort more vulnerable to failure. Prevention requires recognition and mitigation of the precipitants of stent failure, optimisation of interventional techniques, including image-guided precision percutaneous coronary intervention, and aggressive modification of a patient's cardiovascular risk factors. Management of stent failure in the CTO population is technically challenging and itself begets recurrence. We aim to provide a comprehensive review of factors influencing stent failure in the CTO population and strategies to attenuate these.

Clinical Implications of "Tailored" Antiplatelet Therapy in Patients With Chronic Total Occlusion

Background

Clopidogrel nonresponsiveness is a prognostic marker after percutaneous coronary intervention. Prasugrel and ticagrelor provide a better platelet inhibition and represent the first‐line antiplatelet treatment in acute coronary syndrome. We sought to assess the prognostic impact of high platelet reactivity (HPR) and the potential clinical benefit of a “tailored” escalated or changed antiplatelet therapy in patients with chronic total occlusion.

Methods and Results

From Florence CTO‐PCI (chronic total occlusion‐percutaneous coronary intervention) registry, platelet function assessed by light transmission aggregometry, was available for 1101 patients. HPR was defined by adenosine diphosphate test ≥70% and optimal platelet reactivity by adenosine diphosphate test <70%. The endpoint of the study was long‐term cardiac survival. Patients were stratified according to light transmission aggregometry results: optimal platelet reactivity (82%) and HPR (18%). Means for the adenosine diphosphate test were 44±16% versus 77±6%, respectively. Three‐year survival was significantly higher in the optimal platelet reactivity group compared with HPR patients (95.3±0.8% versus 86.2±2.8%; P<0.001). With the availability of new P2Y₁₂ inhibitors, a deeper platelet inhibition (46±17%) and similar survival to the optimal platelet reactivity group were achieved in patients with HPR on clopidogrel therapy after escalation. Conversely, HPR on clopidogrel therapy “not switched” was associated with cardiac mortality (hazard ratio 2.37; P=0.003) after multivariable adjustment.

Conclusions

HPR on treatment could be a modifiable prognostic marker by new antiaggregants providing a deeper platelet inhibition associated with clinical outcome improvement in complex chronic total occlusion patients. A “tailored” antiplatelet therapy, also driven by the entity of platelet inhibition, could be useful in these high risk setting patients.