Evaluation of Infarct-Related Coronary Artery Patency and Microcirculatory Function After Facilitated Percutaneous Primary Coronary Angioplasty

The role of residual intrastent thrombus during primary angioplasty: insights from the COCTAIL II study

AIMS

Recent frequency-domain optical coherence tomography studies showed that a complete removal of thrombotic materials is rarely achieved after percutaneous coronary interventions for ST segment elevation myocardial infarction. Residual intrastent thrombus can embolize distally leading to microcirculatory injury. The aim was to find a possible correlation between residual intrastent thrombus and angiographic indexes of myocardial reperfusion.

METHODS

The population consisted of 128 ST segment elevation myocardial infarction patients enrolled in the COCTAIL II trial. Intrastent thrombus at optical coherence tomography was defined as the maximum percentage value of thrombus area (thrombus area/stent area × 100 in the cross-section with largest thrombus). A thrombus area of at least 16% (mean value) was considered indicative of high residual intrastent thrombus. The following angiographic indexes of myocardial reperfusion were evaluated: thrombolysis in myocardial infarction (TIMI) value, corrected TIMI frame count and myocardial blush grade.

RESULTS

Angiographic and optical coherence tomography results are available in 119 patients: 64 had a maximum percentage value of thrombus area less than 16%, whereas the remaining 55 had a residual intrastent thrombus at least 16%. No differences were found regarding the microcirculatory indexes at baseline angiogram. After intervention, patients with intrastent thrombus less than 16% showed a significant improvement in the final TIMI value (2.87 ± 0.33 vs 2.67 ± 0.54; P = 0.014), final TIMI frame count (11.71 ± 4.58 vs 18.04 ± 17.32; P = 0.012) and a nonsignificant improvement in the final myocardial blush grade value (2.58 ± 0.58 vs 2.43 ± 0.76; P = 0.255).

CONCLUSION

Data obtained from this ancillary study of the COCTAIL II suggest that the presence of high residual intrastent thrombus in patients undergoing primary angioplasty is associated with worsened final microcirculatory indexes.

Impact of Initial Culprit Vessel Flow on Infarct Size, Microvascular Obstruction, and Myocardial Salvage in Acute Reperfused ST-Elevation Myocardial Infarction

Data on the impact of initial Thrombolysis In Myocardial Infarction (TIMI) flow in the culprit coronary artery on myocardial damage after ST-elevation myocardial infarction (STEMI) are limited. Aim of this multicenter study was, therefore, to elucidate the impact of TIMI flow grade before percutaneous coronary intervention (PCI) on infarct size (IS), myocardial salvage index (MSI), and microvascular obstruction (MVO) assessed by cardiac magnetic resonance (CMR) imaging in patients with STEMI. We enrolled 738 patients with STEMI reperfused by primary PCI within 12 hours after symptom onset at 8 centers. Impaired coronary flow was defined as an initial coronary TIMI flow grade ≤1, whereas preserved coronary flow was defined as an initial coronary TIMI flow grade ≥2. CMR was performed in median 3 days (interquartile range 2 to 4 days) after infarction using a standardized infarction protocol. IS, MVO, and MSI were determined in central core laboratory-masked analyses. The primary clinical end point of the study was the time to major adverse cardiac events defined as death, reinfarction, and new onset of heart failure within 12 months after infarction. TIMI flow ≤1 before PCI was present in 507 patients (68.7%) and was significantly associated with larger IS (19% left ventricular [LV] vs 9% LV; p <0.001), less MSI (0.46 vs 0.65; p <0.001), reduced left ventricular ejection fraction (49% vs 55%; p <0.001), and a higher extent of MVO (0.6% LV vs 0.0% LV; p <0.001). Moreover, TIMI flow before PCI was identified as an independent predictor of IS, MVO, and MSI. However, there were no significant differences in major adverse cardiac event rates between groups (6.1% vs 7.5%; p = 0.48). In conclusion, TIMI flow pre-PCI is reversely associated with myocardial injury and is an independent predictor of myocardial damage assessed by CMR.

Antithrombotic therapy before, during and after emergency angioplasty for ST elevation myocardial infarction

The first three hours after symptom onset hold the maximum potential for myocardial reperfusion and salvage in ST-elevation myocardial infarction (STEMI) patients. During this period timely primary percutaneous coronary intervention (PPCI) or, when PPCI is not promptly feasible, pre-hospital administration of fibrinolyis or a glycoprotein IIb/IIIa-inhibitor (GPI) have been shown to restore coronary patency and reperfusion and even result in myocardial infarction (MI) abortion. On the other hand, oral antiplatelet therapy may not yet guarantee sufficient platelet inhibition. Patients presenting after this golden time have less, if any, benefit from an aggressive antithrombotic treatment prior to PPCI. Antithrombotic treatment during primary angioplasty should be tailored on the basis of the coronary thrombotic burden, vascular approach and the patient's risk of bleeding complications. A GPI-based approach may be favourable in patients presenting early with large MI and high thrombus burden, whereas a bivalirudin-based approach without GPI may be preferred in patients with higher bleeding risk. There are no data to support the use of GPI in bailout conditions. The powerful oral P2Y₁₂ inhibitors, prasugrel and ticagrelor, have been clearly shown to prevent stent thrombosis and recurrent ischaemic events after emergency percutaneous coronary intervention in STEMI patients. Open issues remaining are the treatment of patients with high bleeding risk, such as the elderly and those requiring anticoagulation, as well as the duration of dual antiplatelet therapy after STEMI.

Reproducibility of serial optical coherence tomography measurements for lumen area and plaque components in humans (The CLI-VAR [Centro per la Lotta Contro l'Infarto-variability] II study)

Frequency-domain optical coherence tomography (FD-OCT) is a promising intracoronary imaging technique to study atherosclerosis. Indeed, its unprecedented spatial resolution allows the assessment of fibrous cap thickness, lipid pool and features of plaque vulnerability. Aim of this study was to determine the reproducibility of the in vivo FD-OCT measurements of lumen area and plaque components in serial studies. Twenty-six patients undergoing FD-OCT assessment of intermediate lesion during coronary angiography were included in this study. FD-OCT pullbacks were acquired twice from the same coronary segment at interval of 5 min without additional intervention and analyzed off-line at an independent imaging core laboratory. Lumen diameter (LD), lumen area (LA), fibrous cap (FC) thickness and lipid pool (LP) arc extension measurements were compared in 440 matched frames. Both the per-segment and per-frame analyses showed excellent correlation coefficients for the inter-pullback comparisons for all parameters explored (R > 0.95 and p < 0.001 in all cases). Accordingly, the Bland-Altman estimates of bias showed non-significant differences in the inter-pullback comparisons at all levels. Per-frame analysis showed a slightly variations of LA in 45.8% of cases with changes greater than 2% likely related to different phases of cardiac cycle. Nevertheless, nor FC thickness or circumferential arc of LP were affected by LA changes during serial FD-OCT acquisition. This study showed an excellent reproducibility of lumen and plaque component measurements obtained with FD-OCT in vivo. Thus, this intracoronary imaging technique could be used to assess atherosclerosis progression and describe accurate plaque evolution in repeated serial studies.

Mechanical post-conditioning in STEMI patients undergoing primary percutaneous coronary intervention

Although early myocardial reperfusion via primary percutaneous coronary intervention (PCI) allows the preservation of left ventricular function and improves outcome, the acute restoration of blood flow may contribute to the pathophysiology of infarction, a complex phenomenon called reperfusion injury. First described in animal models of coronary obstruction, mechanical post-conditioning, a sequence of repetitive interruption of coronary blood flow applied immediately after reopening of the occluded vessel, was able to reduce the infarct size. However, evidence of its real benefit remains controversial. This review describes the mechanisms of post-conditioning action and the different protocols employed focusing on its impact on primary PCI outcome.

A pharmacodynamic comparison of 5 anti-platelet protocols in patients with ST-elevation myocardial infarction undergoing primary PCI

Background

Despite advances in anti-platelet treatments, there still exists an early increase in both ischemic as well as bleeding events following primary PCI in patients with ST-elevation myocardial infarction (STEMI). Platelet inhibition data of different anti-platelet treatments in the acute phase of a myocardial infarction might offer some insight into these problems. The aim of this study was to evaluate the pharmacodynamic profile of 5 different anti-platelet treatments in the acute phase of STEMI in patients undergoing primary PCI.

Methods

A total of 223 STEMI patients undergoing primary PCI were prospectively included. Patients received either pre-hospital clopidogrel only, pre-hospital clopidogrel followed by prasugrel switch in the cath lab, prasugrel treatment only, pre-hospital clopidogrel followed by ticagrelor switch in the cath lab or pre-hospital ticagrelor only. Platelet reactivity was measured serially using vasodilator-stimulated phosphoprotein (VASP).

Results

Patients receiving pre-hospital clopidogrel followed by prasugrel switch showed similar platelet inhibition data as patients receiving prasugrel only, with more than 90% being good responders the day after PCI. Average time from prasugrel administration to a VASP value of <50% was 1.5 hours. In patients receiving pre-hospital ticagrelor, 50% were good responders at completion of PCI and average time to a VASP-value of <50% was 2.3 hours. Only 32% of patients receiving clopidogrel only were responders the day after PCI.

Conclusions

Switching from an upstream bolus dose of clopidogrel to prasugrel at the time of PCI, appeared as a safe and feasible option with no tendency for overshoot or attenuation of platelet inhibition. Pre-hospital administration of ticagrelor was associated with a 50% good responder rate at completion of PCI.

Trends in treatment delays for patients with acute ST-elevation myocardial infarction treated with primary percutaneous coronary intervention

BACKGROUND

Treatment delay is an important prognostic factor for patients with acute ST-elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI). We aimed to determine recent trends in these delays and factors associated with longer delays.

METHODS

We compared two datasets collected in Helsinki University Central Hospital in 2007-2008 (HUS-STEMI I) and 2011-2012 (HUS-STEMI II), a total of 500 patients treated with primary PCI within 12 hours of the onset of symptoms.

RESULTS

Delays of the emergency medical system (EMS) were longer in HUS-STEMI I than II (medians 81 vs. 67 min, respectively, p < 0.001). Although door-to-balloon times were longer in the later dataset (33 vs. 48 min, p < 0.001) most of the patients (75.3% vs. 62.8%, respectively, p = 0.010) were treated within the recommendation (<60 min) of the European Society of Cardiology (ESC). In HUS-STEMI II, patient arrival at the hospital during off-hours was associated with longer door-to-balloon time (40 and 57.5 min, p = 0.001) and system delay (111 and 127 min, p = 0.009). However, in HUS-STEMI I, arrival time did not impact the delays. Longer system delay was associated with higher mortality rates.

CONCLUSIONS

Though the delays inside the hospital have increased they are still mostly within the ESC guidelines. Still, only about half of the patients are treated within a system delay of recommended two hours. Albeit our results are good in comparison with previous studies, further efforts for decreasing the delays particularly within the EMS should be established.

Coronary Heart Disease in Postmenopausal Women with Type II Diabetes Mellitus and the Impact of Estrogen Replacement Therapy: A Narrative Review

Coronary heart disease is the main cause of death in postmenopausal women (PMW); moreover its mortality exceeds those for breast cancer in women at all ages. Type II diabetes mellitus is a major cardiovascular risk factor and there is some evidence that the risk conferred by diabetes is greater in women than in men. It was established that the deficiency of endogenous estrogens promotes the atherosclerosis process. However, the impact of estrogen replacement therapy (ERT) on cardiovascular prevention remains controversial. Some authors strongly recommend it, whereas others revealed a concerning trend toward harm. This review tries to underlines the different components of cardiovascular risk in diabetic PMW and to define the place of ERT.

Invasive assessment modalities of unprotected left main stenosis

Among all coronary lesions, the decision-making process for the treatment of unprotected left main (ULM) stem lesions is still challenging. Indeed, the optimal therapeutic strategy for patients with ULM disease remains controversial: coronary artery bypass grafting was established as the gold standard, but it is without doubt that percutaneous coronary intervention (PCI) performed by experienced operators achieves good results at long term follow up, especially in cases where the ostium and/or shaft of ULM are treated. Thanks to the widespread use of invasive assessment of atherothrombotic ULM stenosis, improved selection of PCI cases and techniques of stenting, better outcomes are now possible. This review seeks to define the place of PCI in ULM disease by describing the different modalities of ULM stenosis assessment.

Angiographic outcomes with early eptifibatide therapy in non-ST-segment elevation acute coronary syndrome (from the EARLY ACS Trial)

Early administration of glycoprotein IIbIIIa inhibitors results in improved angiographic parameters, including thrombolysis in myocardial infarction (TIMI) flow grade, corrected TIMI frame count, and TIMI myocardial perfusion grade (TMPG) among patients with ST-segment elevation myocardial infarction. Whether the same is true in the setting of non-ST-segment elevation acute coronary syndrome is unknown. The goal of the early glycoprotein IIbIIIa inhibition in non-ST-segment elevation acute coronary syndrome (EARLY ACS) angiographic substudy was to compare angiographic outcomes among patients with non-ST-segment elevation acute coronary syndrome who were administered early routine versus delayed provisional eptifibatide. Of 9,406 patients in the EARLY ACS trial, 2,066 patients were included in the angiographic substudy (early routine eptifibatide [n=1,042] or early placebo [n=1,024] with delayed provisional eptifibatide after angiography and before percutaneous coronary intervention [PCI]). The angiographic substudy primary end point was the incidence of TMPG 3 before and after PCI. TMPG 3 before (43.7% vs 44.9%, p=0.58) and after PCI (52.4% vs 50.1%, p=0.73) was similar for early routine versus delayed provisional eptifibatide, respectively. Angiographic procedural complications consisting of a composite of loss of side branch, abrupt vessel closure, distal embolization, and no reflow occurred less frequently in early routine group versus delayed provisional group (9.3% vs 13.6%, respectively, p=0.01). In the EARLY ACS angiographic substudy, the use of early routine eptifibatide resulted in fewer angiographic procedural complications. These data provide support for the use of eptifibatide in the catheterization laboratory during high-risk cases merely to prevent angiographic procedural complications.

Pharmacological and physical prevention and treatment of no-reflow after primary percutaneous coronary intervention in ST-segment elevation myocardial infarction

After successful primary percutaneous coronary intervention in ST-segment elevation myocardial infarction, adequate myocardial reperfusion is not achieved in up to 50% of patients. This phenomenon of no-reflow is associated with a poor in-hospital and long-term prognosis. Four main factors are thought to contribute to the occurrence of no-reflow: ischaemic injury; reperfusion injury; distal embolization; susceptibility of the microcirculation to injury. This review evaluates the literature, and in particular the clinical trials, concerned with pharmacological and physical methods for prevention and treatment of no-reflow. A number of drugs may improve no-reflow experimentally and clinically, but some have not yet been associated with conclusive improvements in clinical outcome. The complex interacting factors in no-reflow make it unlikely that any single agent will be effective for all patients. Confirmed methods known to be beneficial in the prevention of no-reflow (such as aspirin therapy, chronic statin therapy, blood glucose control, thrombus aspiration in patients with a high thrombus burden and ischaemic preconditioning) should be offered to patients as often as possible, to prevent and treat no-reflow.

Myocardial perfusion reserve in spared myocardium: correlation with infarct size and left ventricular ejection fraction

PURPOSE

Left ventricular ejection fraction (LVEF) after myocardial infarction is considered to be determined by the size of the infarction and residual function of the spared myocardium. Myocardial perfusion reserve (MPR) has been shown to be a strong prognostic factor in patients with ischaemic heart failure, even stronger than LVEF. In the present study, the interrelationship between MPR, LVEF and infarct size was investigated.

METHODS

In total, 102 patients with a prior history of myocardial infarction were included. All underwent rest and stress (13)N-ammonia and gated (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) for evaluation of myocardial ischaemia and viability. FDG polar maps were used to determine the size of the infarction. The LVEF was obtained by gated (18)F-FDG PET or another available method within 3 months of the PET scan. MPR was obtained per segment in the spared myocardium.

RESULTS

The mean age of the subjects was 68 ± 12 years. Global MPR was 1.63 ± 0.51. The mean LVEF was 36 ± 10 % and mean infarct size 23.72 ± 14.8 %. A linear regression model was applied for the analysis considering the LVEF as a dependent variable. All risk factors, mean stress flow, infarct size and MPR were entered as variables. The infarct size (p < 0.001) and MPR (p = 0.04) reached statistical significance. In a multivariate model MPR had a stronger correlation with LVEF than infarct size.

CONCLUSION

In patients with a prior history of myocardial infarction, LVEF is not just related to infarct size but also to MPR in the spared myocardium.

Association between proximal stent edge positioning on atherosclerotic plaques containing lipid pools and postprocedural myocardial infarction (from the CLI-POOL Study)

Postprocedural myocardial infarction is an ominous complication of percutaneous coronary intervention (PCI). Despite several patient, lesion, and procedural factors that may affect its occurrence and severity, it is unclear if implanting a stent edge on a coronary lipid pool, as appraised by optical coherence tomography (OCT), adversely affects outcomes. The aim of this study was to assess the association between postprocedural myocardial infarction and the implantation of a stent edge on a lipid pool, as assessed by OCT. A database was screened for patients without ongoing myocardial infarctions; who underwent PCI with stenting for single, native, de novo lesions; without periprocedural side-branch occlusion or compromise; who underwent post-PCI OCT; and had postprocedural myocardial infarctions. These subjects were matched 1:1 with patients with similar features but without postprocedural myocardial infarctions. Plaque characterization with OCT was performed using established criteria. Specifically, lipid pools within stent edges were quantified by computing the number of involved quadrants and the degree of lipid arc on cross-sectional images. A total of 30 patients were included (15 with postprocedural myocardial infarctions and 15 controls without infarctions). Whereas no patient or control subject had lipid pools in correspondence to distal stent edges, landing of proximal stent edges on lipid pools was significantly more frequent in patients than in controls (10 [66%] vs 2 [13%], p = 0.009), Moreover, patients with postprocedural myocardial infarctions had more extensive lipid pools at proximal stent edges than those without postprocedural myocardial infarctions. Accordingly, lipid pool arc at proximal stent edge was significantly associated with peak post-PCI creatine kinase-MB/upper limit of normal ratio (Spearman's ρ = 0.49, p = 0.006). In conclusion, incomplete stent coverage of coronary lipid pools appears to be associated with an increased risk for postprocedural myocardial infarction in patients who undergo PCI.

Equilibrium radionuclide angiography for evaluating the effect of facilitated percutaneous coronary intervention on ventricular synchrony in patients with acute myocardial infarction

BACKGROUND

It is unclear whether facilitated percutaneous coronary intervention (PCI) via a transradial approach therapy is preferable to primary PCI, with improved ventricular synchrony performance (VS), in Chinese patients.

METHODS AND RESULTS

The 152 patients with their first anterior acute myocardial infarction (AMI) were randomized to a primary PCI group or facilitated PCI group. In the 1(st) week and 6(th) month after AMI onset, the parameters of VS were measured by equilibrium radionuclide angiography with ventricular phase analysis. The rate of TIMI grade-3 flow in the infarct-related artery pre-PCI in the facilitated PCI group was higher than that in the primary PCI group (30.56% vs. 8.45%, P=0.001). At the 6(th) month post-AMI, the parameters of time to peak ejection rate, phase shift and peak phase standard deviation were lower than in the primary PCI group (P<0.05, respectively). The incidence of recurrent ischemia and new or worsening congestive heart failure post-AMI in the facilitated PCI group was significantly lower than that in the primary PCI group (2.78% vs. 9.86%, P=0.043; 2.78% vs. 12.68%, P=0.028).

CONCLUSIONS

Facilitated PCI via a transradial approach might significantly inhibit left ventricular remodeling and improve left ventricular function because of the complete, persistent patency of the infarct-related artery with few complications of vessel access and bleeding.

Antiplatelet therapy in patients with ST-elevation myocardial infarction undergoing myocardial revascularisation: beyond clopidogrel

BACKGROUND

Despite revascularisation, outcomes among patients presenting with ST-elevation myocardial infarction (STEMI) remain suboptimal.

SCOPE

This review compares clopidogrel, ticagrelor and prasugrel as antiplatelet strategies with a particular focus on STEMI. Medline and Google Scholar were searched for relevant terms and citations from these articles were also assessed.

FINDINGS

While clopidogrel represented an important therapeutic advance, variations in platelet response and a relatively slow onset of action compromise outcomes in some patients. Ticagrelor and prasugrel are more effective than clopidogrel, although essentially only one large study supports each drug. Nevertheless, a detailed examination of the evidence reveals several issues that may influence the decision to prescribe ticagrelor instead of prasugrel and vice versa. Arguably, prasugrel could be the preferred strategy in STEMI, reflecting the drugs' efficacy in clopidogrel-naïve patients, the most common group in clinical practice. Conversely, ticagrelor may be a better option than clopidogrel in clopidogrel-pretreated patients showing a mortality benefit irrespective of clopidogrel pre-treatment. The clinical benefits offered by prasugrel and ticagrelor need to be offset against the increased cost and we suggest an algorithm for using these new compounds in the primary percutaneous coronary intervention (PCI) setting. The risk of bleeding associated with prasugrel is similar to that of clopidogrel and ticagrelor following exclusion of at-risk patients. Nevertheless, prasugrel may be especially appropriate for STEMI patients undergoing PCI who are considered to be at high risk of ischaemia. Conversely, ticagrelor's short half-life, while potentially a limitation during maintenance therapy, may reduce bleeding risk if the patient undergoes CABG during the same hospital admission, although confirmatory studies are needed.

CONCLUSION

Future studies also need to address several other outstanding issues, such as the subsequent approach if patients do not undergo PCI, and to overcome limitations in and differences between the primary studies. In particular, head-to-head comparisons need to compare directly the risks and benefits of ticagrelor and prasugrel in STEMI patients. These caveats notwithstanding, ticagrelor and prasugrel markedly improve the prognosis for patients with STEMI.

The effect of pre-hospital glycoprotein IIb-IIIa inhibitors on angiographic outcome in STEMI patients who are candidates for primary PCI

OBJECTIVES

Aim of this study was to assess the effect of early initiation of high bolus dose tirofiban on top of dual antiplatelet therapy on angiographic outcome before and after primary percutaneous coronary intervention (PCI) in ST-elevation myocardial infraction patients.

BACKGROUND

Glycoprotein IIb/IIIa inhibitors are effective inhibitors of platelet aggregation, and have shown to reduce thrombotic complications in patients undergoing PCI.

METHODS

This is a pre-specified angiographic analysis of the On-TIME 2 trial (N = 984) and its open label run-in phase (N = 414). All angiographic parameters, including quantitative coronary angiography (QCA) were performed in an independent angiographic core lab.

RESULTS

Of the 1,398 patients, 709 patients (50.7%) were randomized to pre-hospital tirofiban. An open infarct related vessel (TIMI 2 or 3 flow) at initial angiography was more often present in the tirofiban group as compared to the no tirofiban group (58.3% vs. 49.7%, P = 0.002). Tirofiban also reduced initial thrombus burden (P for trend = 0.035) as well as thrombus grade 5 (46.9% vs. 54.3%, P = 0.016) and showed a trend toward a reduction in large thrombus burden (LTB) (69.4% vs. 74.5%, P = 0.055). After PCI, a trend towards a lower corrected TIMI frame count (cTFC) in the tirofiban group was found. A significant interaction was found with time of initiation of study drug, with highest efficacy of tirofiban when given within 76 min after symptom onset, with a significantly lower cTFC after PCI (21.9 ± 17.6 vs. 23.9 ± 18.5, P = 0.008, P for interaction P = 0.006).

CONCLUSION

In patients undergoing primary PCI, pre-hospital administration of tirofiban reduces initial thrombus burden and improves initial patency of the infarct related vessel before PCI. Initiation of tirofiban seems to be most effective when given very early after the onset of symptoms; however, this finding needs confirmation in other studies.

CLINICAL TRIAL REGISTRATION

The On-TIME 2 trial is registered, at http://isrctn.org, number ISRCTN06195297.