Platelet glycoprotein IIb/IIIa receptor blockade and coronary resistance in unstable angina

Impact of drug-eluting stents on left ventricular wall motion after successful reperfusion of first anterior ST elevation myocardial infarction

BACKGROUND

Timely myocardial reperfusion by primary percutaneous coronary intervention (pPCI) prevents the development of left ventricular (LV) dysfunction after myocardial infarction (MI). We aimed to investigate whether bare-metal stents (BMS) and drug eluting stents (DES) differently affect the recovery of LV function in patients with ST-elevation MI (STEMI).

METHODS

Overall 103anterior STEMI patients were retrospectively analyzed. All patients had single vessel disease with culprit lesion at the left anterior descending coronary artery. Patients were categorized in DES group (N.=67) and BMS group (N.=36). Changes in LV contractility were assessed by trans-thoracic echocardiogram as Left Ventricular Wall Motion Score Index (LVWMSI). Follow-up visits were performed between 6 and 12 months after hospital discharge.

RESULTS

Compared to baseline, LV ejection fraction (EF) remained unchanged between the two groups at the follow-up; LVWMSI significantly improved in patients treated with DES (1.95±0.25 vs. 1.78±0.38, P<0.05), whereas did not change in those treated with BMS (2.09±0.21 vs. 1.98±0.33, P: not significant). At follow-up the LVWMSI was significantly higher in patients with DES than with BMS (P=0.048). LV end-systolic and end-diastolic volumes (LVESV, LVEDV) significantly increased in patients receiving a BMS, whereas it did not change in those receiving a DES (P<0.05). Multivariate analysis adjusted for age, gender, type of stent (DES or BMS), and type of revascularization (primary PCI or rescue PCI or thrombolysis + PCI) showed that DES implantation was an independent predictor of LVWMSI improvement (OR: 3.8 [1.143-12.969] P=0.03).

CONCLUSIONS

DES implantation is associated with a favorable impact on LV remodeling and regional contractility.

Ticagrelor and preconditioning in patients with stable coronary artery disease (TAPER-S): a randomized pilot clinical trial

Background

Ticagrelor is a reversibly binding, direct-acting, oral, P₂Y₁₂ antagonist used for the prevention of atherothrombotic events in patients with coronary artery disease (CAD). Ticagrelor blocks adenosine reuptake through the inhibition of equilibrative nucleoside transporter 1 (ENT-1) on erythrocytes and platelets, thereby facilitating adenosine-induced physiological responses such as an increase in coronary blood flow velocity. Meanwhile, adenosine plays an important role in triggering ischemic preconditioning through the activation of the A1 receptor. Therefore, an increase in ticagrelor-enhanced adenosine bioavailability may confer beneficial effects through mechanisms related to preconditioning activation and improvement of coronary microvascular dysfunction.

Methods

To determine whether ticagrelor can trigger ischemic preconditioning and influence microvascular function, we designed this prospective, open-label, pilot study that enrolled patients with stable multivessel CAD requiring staged, fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI). Participants will be randomized in 1:1 ratios either to ticagrelor (loading dose (LD) 180 mg, maintenance dose (MD) 90 mg bid) or to clopidogrel (LD 600 mg, MD 75 mg) from 3 to 1 days before the scheduled PCI. The PCI operators will be blinded to the randomization arm. The primary endpoint is the delta (difference) between ST segment elevations (in millimeters, mm) as assessed by intracoronary electrocardiogram (ECG) during the two-step sequential coronary balloon inflation in the culprit vessel. Secondary endpoints are 1) changes in coronary flow reserve (CFR), index of microvascular resistance (IMR), and FFR measured in the culprit vessel and reference vessel at the end of PCI, and 2) angina score during inflations. This study started in 2018 with the aim of enrolling 100 patients. Based on the rate of negative FFR up to 30% and a drop-out rate up to 10%, we expect to detect an absolute difference of 4 mm among the study arms in the mean change of ST elevation following repeated balloon inflations. All study procedures were reviewed and approved by the Ethical Committee of the Catholic University of Sacred Heart.

Discussion

Ticagrelor might improve ischemia tolerance and microvascular function compared to clopidogrel, and these effects might translate to better long-term clinical outcomes.

Trial registration

EudraCT No. 2016–004746-28. No. NCT02701140. 

Trial status

Information provided in this manuscript refers to the definitive version (n. 3.0) of the study protocol, dated 31 October 2017, and includes all protocol amendments. Recruitment started on 18 September 2018 and is currently ongoing. The enrollment is expected to be completed by the end of 2019.

Trial sponsor

Fondazione Policlinico Universitario A. Gemelli – Roma, Polo di Scienze Cardiovascolari e Toraciche, Largo Agostino Gemelli 8, 00168 Rome, Italy.

Design and Rationale for comParison Between ticagreLor and clopidogrEl on mIcrocirculation in Patients with Acute cOronary Syndrome Undergoing Percutaneous Coronary Intervention (PLEIO) Trial

It has been previously demonstrated that ticagrelor can reduce mortality compared to clopidogrel in acute coronary syndrome (ACS) patients. However, the mechanism for this mortality reduction remains uncertain. The objective of the present study is to assess the impact of chronic ticagrelor treatment on microvascular circulation. A total of 120 participants aged 20–85 years with clinical diagnosis of ACS will be randomized in a 1:1 fashion to the following two groups: ticagrelor 90 mg twice daily; clopidogrel 75 mg once daily. To evaluate the status of microcirculation, the primary end point is coronary microvascular dysfunction measured using an index of microcirculatory resistance (IMR) at 6 months after receiving the study agent. The purpose of this trial is to investigate whether ticagrelor, beyond its antiplatelet efficacy, could improve coronary microcirculation more effectively than clopidogrel for patients with ACS.

Doppler Versus Thermodilution-Derived Coronary Microvascular Resistance to Predict Coronary Microvascular Dysfunction in Patients With Acute Myocardial Infarction or Stable Angina Pectoris

Coronary microvascular resistance is increasingly measured as a predictor of clinical outcomes, but there is no accepted gold-standard measurement. We compared the diagnostic accuracy of 2 invasive indices of microvascular resistance, Doppler-derived hyperemic microvascular resistance (hMR) and thermodilution-derived index of microcirculatory resistance (IMR), at predicting microvascular dysfunction. A total of 54 patients (61 ± 10 years) who underwent cardiac catheterization for stable coronary artery disease (n = 10) or acute myocardial infarction (n = 44) had simultaneous intracoronary pressure, Doppler flow velocity and thermodilution flow data acquired from 74 unobstructed vessels, at rest and during hyperemia. Three independent measurements of microvascular function were assessed, using predefined dichotomous thresholds: (1) coronary flow reserve (CFR), the average value of Doppler- and thermodilution-derived CFR; (2) cardiovascular magnetic resonance (CMR) derived myocardial perfusion reserve index; and (3) CMR-derived microvascular obstruction. hMR correlated with IMR (rho = 0.41, p <0.0001). hMR had better diagnostic accuracy than IMR to predict CFR (area under curve [AUC] 0.82 vs 0.58, p <0.001, sensitivity and specificity 77% and 77% vs 51% and 71%) and myocardial perfusion reserve index (AUC 0.85 vs 0.72, p = 0.19, sensitivity and specificity 82% and 80% vs 64% and 75%). In patients with acute myocardial infarction, the AUCs of hMR and IMR at predicting extensive microvascular obstruction were 0.83 and 0.72, respectively (p = 0.22, sensitivity and specificity 78% and 74% vs 44% and 91%). We conclude that these 2 invasive indices of coronary microvascular resistance only correlate modestly and so cannot be considered equivalent. In our study, the correlation between independent invasive and noninvasive measurements of microvascular function was better with hMR than with IMR.

Concordance of angiographic and electrocardiographic indexes of microvascular obstruction: myocardial haemorrhage role

BACKGROUND

Angiographic and electrocardiographic (ECG) indexes of microvascular obstruction (MVO) have been described. We aimed at assessing by cardiac magnetic resonance (CMR) anatomical features underlying concordance between them.

METHODS

Forty-one patients were enrolled. Patients presented with neither angiographic nor ECG indexes of MVO (without MVO) (44%), with either angiographic or ECG indexes of MVO (discordant with MVO) (22%) or with both angiographic and ECG indexes of MVO (concordant with MVO) (34%). All patients underwent in-hospital CMR. Echocardiographic data obtained after 6 months were compared with those obtained in hospital.

RESULTS

Concordant patients with MVO had larger infarct size, lower myocardial salvage index and higher rate of myocardial haemorrhage (all assessed by CMR) [33% (25-41%), 15% (10-29%) and 88%, respectively] as compared with patients without MVO [12% (9-16%), 66% (52-79%) and 0%; Bonferroni-adjusted P < 0.001, Bonferroni-adjusted P < 0.001 and P < 0.001, respectively], or with discordant ones [25% (21-39%), 35% (20-48%) and 7%; Bonferroni-adjusted P = 0.03, Bonferroni-adjusted P = 0.002 and P = 0.04, respectively]. After 6 months, ejection fraction significantly decreased in concordant patients with MVO (P < 0.001) without significant changes in the other groups.

CONCLUSIONS

Concordance of angiographic and ECG indexes of MVO reflects more severe myocardial damage translating into unfavourable left ventricular remodelling.

Advances in coronary microvascular dysfunction

Considerable focus has been directed towards coronary arterial disease in the management of coronary heart disease, however the coronary microcirculation plays a major role in the regulation of coronary blood flow. Thus while we have multiple medical and revascularisation therapies to treat large vessel coronary artery disease, therapies directed towards the microcirculation are very limited. This review paper summarises important aspects of coronary microvascular dysfunction including (a) methods of assessment, (b) clinical classification of associated disorders, (c) possible pathophysiological mechanisms, and (d) potential therapies. Hence this will provide important background to advancing our understanding and management of coronary heart disease by targeting the coronary microcirculation.

Intracoronary abciximab use in patients undergoing PCI at a community hospital: a single operator experience

OBJECTIVE

To evaluate the safety of intracoronary (IC) abciximab during percutaneous coronary intervention (PCI).

BACKGROUND

Adjunctive treatment with glycoprotein IIb/IIIa inhibitors, especially abciximab, during PCI has been shown to improve clinical and procedural outcomes in numerous studies. However, significant bleeding complications exist with its use and this has limited its standard use. Interest has grown in local (IC) use with studies showing safety and long-term effectiveness, especially in patients with high thrombus loads.

METHODS

A retrospective review of records in a database of patients who had PCI by a single operator at the Easton Hospital.

RESULTS

611 patients received IC abciximab, and there were no complications in 610 (98.3%) patients; only 1 had an allergic reaction.

CONCLUSIONS

IC abciximab is safe and has a unique role in the catheterization lab and in patients at high risk of bleeding complications who would benefit from its limited use.

Comparison of coronary flow reserve and fractional flow reserve in patients with versus without diabetes mellitus and having elective percutaneous coronary intervention and abciximab therapy (from the PREDICT Trial)

Patients with diabetes mellitus (DM) have poor long-term outcome after percutaneous coronary intervention (PCI) partly because of microvascular disease and distal embolization. Microvascular obstruction can be assessed by measuring coronary flow reserve (CFR). The Prediction of CK-MB RElease During Successful Stenting Correlating with Indicators of Microvascular ObstruCTion (PREDICT) trial compared the CFR in patients with versus without DM during PCI. Patients undergoing elective PCI were prospectively enrolled according to diabetic (n = 36) and nondiabetic (n = 36) status. All patients received drug-eluting stent with abciximab and were followed for 30-day major adverse cardiac events. CFR and FFR (fractional flow reserve) before and after stenting were measured before and after intracoronary adenosine bolus. Procedural success, MB enzyme of creatine-kinase (CK-MB), troponin I, and high-sensitive C-reactive protein elevation, vascular complications, and major adverse cardiac events were not different. FFR before stenting was 0.77 +/- 0.03 in patients with DM versus 0.76 +/- 0.02 in patients without DM (p = 0.69). FFR after stenting was 0.97 +/- 0.03 and 0.99 +/- 0.01 (p = 0.26), respectively. CFR before stenting was 1.36 +/- 0.31 in patients with DM versus 1.49 +/- 0.25 in patients without DM (p = 0.064). However, CFR after stenting was significantly lower in patients with versus without DM (1.89 +/- 0.30 versus 2.44 +/- 0.67, p <0.001, respectively). CFR after stenting only moderately correlated with CK-MB and high-sensitive C-reactive protein after PCI but did not correlate with 30-day major adverse cardiac events. In conclusion, patients with DM have significantly lower CFR after stenting despite equivalent FFR and myonecrosis compared with patients without DM, indicating greater microvascular obstruction after PCI despite abciximab.

Randomized Early Versus Late Abciximab in Acute Myocardial Infarction Treated With Primary Coronary Intervention (RELAx-AMI Trial)

OBJECTIVES

This prospective randomized trial evaluates the impact of early abciximab administration on angiographic and left ventricular function parameters.

BACKGROUND

Glycoprotein IIb/IIIa inhibitors improve myocardial reperfusion in patients with acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PCI), but optimal timing of administration remains unclear.

METHODS

Two-hundred ten consecutive patients with first AMI undergoing primary PCI were randomized to abciximab administration either in the emergency room (early group: 105 patients) or in the catheterization laboratory, after coronary angiography (late group: 105 patients). Primary end points were initial Thrombolysis In Myocardial Infarction (TIMI) flow grade, corrected TIMI frame count (cTFC), and myocardial blush grade (MBG), as well as left ventricular function recovery as assessed by serial echocardiographic evaluations.

RESULTS

Angiographic pre-PCI analysis showed a significantly better initial TIMI flow grade 3 (24% vs. 10%; p = 0.01), cTFC (78 +/- 30 frames vs. 92 +/- 21 frames; p = 0.001), and MBG 2 or 3 (15% vs. 6%; p = 0.02) favoring the early group. Consistently, post-PCI tissue perfusion parameters were significantly improved in the early group, as assessed by 60-min ST-segment reduction > or =70% (50% vs. 35%; p = 0.03) and MBG 2 or 3 (79% vs. 58%; p = 0.001). Left ventricular function recovery at 1 month was significantly greater in the early group (mean gain ejection fraction 8 +/- 7% vs. 6 +/- 7%, p = 0.02; mean gain wall motion score index 0.4 +/- 0.3 vs. 0.3 +/- 0.3, p = 0.03).

CONCLUSIONS

In patients with AMI treated with primary PCI, early abciximab administration improves pre-PCI angiographic findings, post-PCI tissue perfusion, and 1-month left ventricular function recovery, possibly by starting early recanalization of the infarct-related artery.

Rationale for intracoronary administration of abciximab

The present review aims to describe the pharmacological aspects as well as the available clinical data supporting the choice of intracoronary route of administration for abciximab, an antiplatelet drug used in patients with acute coronary syndromes undergoing percutaneous coronary interventions (PCI). Abciximab is a glycoprotein (GP) IIb/IIIa receptor antagonist which determines a potent inhibition of platelet aggregation and thrombus formation. These properties seem to prevent not only thrombus formation but also to promote (at higher drug concentration) lysis of fresh thrombus. Moreover, differently from the other GP IIb/IIIa inhibitors, abciximab also binds to the vitronectin receptor on endothelial, smooth muscle, and inflammatory cells and to an activated conformation of the aMb2 receptor on leukocytes. Such cross-reactivity raises the possibility that clinical benefits derived from its use may not be exclusively due to its anti-thrombotic effect, but may also be related to the suppression of inflammatory pathways involving platelets, white blood cells, and the vascular endothelium. On such basis, the local administration of abciximab at the site of coronary thrombosis may enhance, by increasing its local concentration, the binding to both platelet and endothelium receptors. The results of several angiographic studies assessing the effect of intracoronary abciximab administration support on clinical grounds its adoption in patients with fresh coronary thrombosis. Indeed, better post-angioplasty coronary flow, greater degree of myocardial salvage and a better left ventricular function recovery have been achieved as compared to the intravenous, systemic, administration of drug's bolus. Condensed Abstract Several studies have highlighted the benefits of abciximab, a potent antiplatelet agent, in patients with acute coronary syndromes undergoing percutaneous coronary interventions. Moreover, differently from the other glycoprotein IIb/IIIa receptor antagonists, abciximab also has non-IIb/IIIa-related properties raising the possibility that clinical benefits derived from its use may not be exclusively due to its anti-thrombotic effect, but may also be related to the suppression of inflammatory pathways. Several angiographic studies in patients with fresh coronary thrombosis and recent clinical studies in patients with acute coronary syndromes undergoing mechanical revascularization support the hypothesis that local administration of abciximab at the site of the culprit coronary artery may facilitate both the de-thrombotic and the non-GP IIb/IIIa-dependent properties of the drug. On such basis, the present review aims to describe the pharmacological aspects as well as the available clinical data supporting the choice of intracoronary route of administration for abciximab.

Changing scenario in chronic ischemic heart disease: therapeutic implications

Over the last 30 years, considerable progress has been made in drug therapy for chronic ischemic heart disease (IHD). Most pharmacologic therapies act by reducing myocardial oxygen consumption, increasing coronary blood flow, improving ventricular relaxation, dilating collateral vessels, and reducing peripheral resistances. Despite "optimal" medical therapy, a large fraction of patients continue to present with angina and myocardial ischemia. Coronary angioplasty (percutaneous transluminal coronary angioplasty) may improve symptoms, but several subgroups of patients, including the elderly, or those who have diabetes mellitus or heart failure, represent high-risk populations that do not always benefit from coronary revascularization. Epidemiologic studies show that life expectancy is longer compared with previous decades and that the prevalence of diabetes is increasing sharply worldwide. In addition, the prevalence of heart failure is growing because of the decreased death rate from acute myocardial infarction and improved survival of patients who have undergone coronary revascularization. We focus on this changing scenario of chronic IHD and propose an innovative approach to the treatment of angina in this context.

Angiographic evaluation of the effect of intracoronary abciximab administration in patients undergoing urgent PCI

BACKGROUND

Recent data suggest that the intracoronary (i.c.) administration of a systemic bolus dose of abciximab during PCI may increase the efficacy of this antiplatelet drug. However, the effect of i.c. abciximab on coronary angiographic flow has been not clarified.

METHODS

We studied 37 consecutive patients with acute coronary syndromes (ACS) who underwent successful urgent PCI on the target vessel and were treated by an i.c. abciximab bolus (0.25 mg/kg) prior to the first balloon inflation (Group IC), and 37 matched controls who were treated by intravenous (i.v.) abciximab bolus at the same dose (Group IV). Corrected TIMI frame count (CTFC) in the culprit and in a non-culprit coronary artery branch was assessed before treatment, immediately after intracoronary administration of abciximab bolus and at the end of the procedure.

RESULTS

After administration of abciximab, CTFC significantly decreased from 48+37 to 33+30 (P=0.001) in the culprit vessel while in the non-culprit vessel it remained unchanged (16+7 pre-treatment and 16+7 post-treatment, P=0.68). Final CTFC was 12+4 in Group IC and 14+5 in Group IV (P=0.069). Post-treatment mean peak of the cardiac enzymes showed a trend toward reduction in Group IC compared with Group IV.

CONCLUSIONS

The i.c. administration of abciximab bolus acutely decreases CTFC through culprit vessels of patients with ACS undergoing urgent PCI. Further studies evaluating the potential clinical benefits associated with i.c. abciximab administration are warranted.

Correlation of Hemodynamic Events with Clinical and Pathological Observations

The correlation of hemodynamic events with clinical or pathological observations is represented by a variety of applications reflecting the broad range of this theme. The position paper describes several cases in which benefits of combining imaging information with transport models of contrast material, can cause a gain in hemodynamic information. What appears to be lack of cohesiveness among the cases illustrates the variety in the application of hemodynamic research to the practice of medicine. Some of the contributions presented at the symposium do not directly apply to clinical medicine, but instead described mathematical models or applications to animal physiology or technical advancements in measuring blood rheology. Although related to this theme topic they fall somewhat outside the main scope. The topics summarized below demonstrate four examples in which translation of the research to the clinical arena can be realized in a short period of time. Overall recommendations for priority objectives related to this topic are provided at the end of this position paper.

Influence of Percutaneous Coronary Intervention on Coronary Microvascular Resistance Index

Background— Coronary microvascular resistance during maximal hyperemia is generally assumed to be unaffected by percutaneous coronary interventions (PCIs). We assessed a velocity-based index of hyperemic microvascular resistance (h-MR v ) by using prototypes of a novel, dual-sensor (Doppler velocity and pressure)–equipped guidewire before and after PCI to test this hypothesis.

Methods and Results— Aortic pressure, flow velocity (h-v), and pressure (h-P d ) distal to 24 coronary lesions were measured simultaneously during maximal hyperemia induced by intracoronary adenosine. Measurements were obtained in the reference vessel before PCI and in the target vessel before and after PCI, stenting, and ultrasound-guided, upsized stenting. h-P d increased from 57.9±17.0 to 85.5±15.6 mm Hg, and h-MR v (ie, h-P d /h-v) decreased from 2.74±1.40 to 1.58±0.61 mm Hg · cm −1 · s after stenting (both P <0.001). The reduction in h-MR v accounted for 34% of the decrease in total coronary resistance achieved by PCI. h-MR v of the target vessel after PCI was lower than that of the corresponding reference vessel despite a higher h-P d in the reference vessel ( P <0.01). Post-PCI baseline MR v was correlated with baseline P d before PCI ( P <0.01).

Conclusions— PCI-induced restoration of P d resulted in a reduction of h-MR v in accordance with the pressure dependence of h-MR v . The decrease in h-MR v to a level below that of the corresponding reference vessel in the immediate post-PCI period and a lowered baseline MR v suggest microvascular remodeling induced by long-term exposure to a low-pressure environment.

Inhibition of platelet activation and aggregation

It has recently been established that platelets are involved at all stages of atherosclerotic disease. A major platelet mediated process is the acute vessel closure at the site of atherosclerotic plaque rupture and there is emerging evidence for platelet adhesion to endothelial cells in the early stage of atherosclerotic disease. This, through engagement of other cells, leads to the development of the atherosclerotic plaque. Beside dietary, cholesterol- and lipid-lowering, and other pharmaceutical approaches antiplatelet therapy plays an important part in the treatment of atherosclerosis and its multifarious clinical manifestations. Antiplatelet therapy and the currently approved substances for oral (acetylsalicylic acid, dipyridamole, cilostazol, ticlopidin and clopidogrel) and parenteral (acetylsalicylic acid, abciximab, eptifibatide and tirofiban) administration are discussed in the following section. Attention is given to each single agent and its mechanism of action. Differences in pharmacodynamic and pharmacokinetic properties are elucidated and outlook on future antiplatelet strategies is discussed.

Medical versus interventional management of stable angina

Several randomized trials have been performed comparing medical management with surgery, medical management with angioplasty, and angioplasty with surgery for patients with stable angina. They were conducted in parallel with the progress of the revascularization techniques and as such, each of them reflects the prevailing practice of its time. Percutaneous revascularization and, to a lesser extent, coronary surgery have been, and it seems they will continue to be, rapidly evolving specialities. Medical management has also improved and future advances are likely to occur. One of the most remarkable advances in medical management is a new concept in metabolic approach in the treatment of angina pectoris. Despite the complexity of drawing conclusions from trials that compared approaches already outperformed in current practice, in this paper we review the relevant literature in an attempt to outline the comparative efficacy of the available treatment strategies.

Use of GPIIb/IIIa inhibitors in cardiovascular medicine

The GPIIb/IIIa inhibitors were the first clinically used anti-integrin therapeutics. They opened the gate to a rapidly developing area of anti-integrin targeting as a therapeutic approach to many diseases. The use of GPIIb/IIIa inhibitors in interventional cardiology is widespread and still increasing, as is the number of percutaneous coronary interventions. There seems to be a class effect of GPIIb/IIIa inhibitors in percutaneous coronary intervention, but there are major differences in the pharmacokinetics and pharmacodynamics of these agents. Currently clinically approved for parenteral use are the Fab fragment abciximab (ReoPro, Lilly) and the small-molecule GPIIb/IIIa inhibitors eptifibatide (Integrilin, Millennium/Schering-Plough) and tirofiban (Aggrastat, Merck). This review focuses on the different pharmacological properties of these agents and summarizes present and future therapeutic use of GPIIb/IIIa inhibitors in cardiovascular and other vascular diseases.