A comparison between upfront high-dose tirofiban versus provisional use in the real-world of non-selected STEMI patients undergoing primary PCI: Insights from the Zwolle acute myocardial infarction registry

What Are Optimal P2Y12 Inhibitor and Schedule of Administration in Patients With Acute Coronary Syndrome?

Guidelines recommend treatment with a P2Y12 platelet adenosine diphosphate receptor inhibitor in patients undergoing elective or urgent percutaneous coronary intervention (PCI), but the optimal agent or timing of administration is still not clearly specified. The P2Y12 inhibitor was initially used for its platelet anti-aggregatory action to block thrombosis of the recanalized coronary artery or deployed stent. It is now recognized that these agents also offer potent cardioprotection against a reperfusion injury that occurs in the first minutes of reperfusion if platelet aggregation is blocked at the time of reperfusion. But this is difficult to achieve with oral agents which are slowly absorbed and often require time-consuming metabolic activation. Patients with ST-segment elevation myocardial infarction who usually have a large mass of myocardium at risk of infarction seldom have sufficient time for upstream-administered oral agents to achieve a therapeutic P2Y12 level of inhibition by the time of balloon inflation. However, optimal treatment could be assured by initiating an IV cangrelor infusion shortly prior to stenting followed by subsequent post-PCI transition to an oral agent, that is, ticagrelor, once success of the recanalization and absence of need for surgical intervention are confirmed. Not only should this sequence provide optimal protection against infarction, it should also negate bleeding if coronary artery bypass grafting should be required since stopping the cangrelor infusion at any time will quickly restore platelet reactivity. It is anticipated that cangrelor-induced myocardial salvage will help preserve myocardial function and significantly diminish postinfarction heart failure.

Early Thrombosuction and Tirofiban Use in Knee and Below-Knee Arterial Thrombosis

BACKGROUND Acute limb ischemia (ALI) is a clinical entity with a high rate of morbidity and mortality. Despite advances and variety of its management, there is still no criterion standard treatment. The goal of this study was to evaluate the effect of tirofiban use on the early and 6-month prognosis of patients with knee and below-knee arterial thrombosis who were treated with percutaneous thrombosuction (PT) within 24 h. MATERIAL AND METHODS Data of consecutive ALI patients who were diagnosed with popliteal and infra-popliteal arterial thrombosis and underwent PT procedure within 24 h between January 2010 and September 2015 were evaluated retrospectively. Patients were separated into 2 groups according to tirofiban usage. RESULTS A total of 105 patients (mean age 67±16; 53% men) were included in the study. Atrial fibrillation (n 64, 61%) and hypertension (n 60, 57%) were the most frequent comorbidities in patients with thromboembolic events. A significantly higher rate of distal embolization (6% vs. 16%; p=0.01) and slow-flow (17% vs. 30%; p<0.01) developed in patients who were not treated with tirofiban after the PT procedure. Although major and minor bleeding were more frequent in the tirofiban group, only the rate minor bleeding was statistically significant (29% vs. 9%, p=0.001). Reverse embolic event ratio was similar in both groups. Although there was a higher rate of amputation in patients not treated with tirofiban, the difference was not significant. CONCLUSIONS Adding tirofiban to PT reduces angiographic thromboembolic complications. Usage of tirofiban in patients prone to thromboembolic events may be useful for improving success of the PT procedure, with a reasonable bleeding ratio.

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.

Combined cardioprotectant and antithrombotic actions of platelet P2Y12 receptor antagonists in acute coronary syndrome: just what the doctor ordered

Since the P2Y12 receptor antagonists were first introduced, they have been extensively tested in patients with acute coronary syndrome and are now standard of care. These antiplatelet drugs are very effective in reducing subsequent cardiovascular events, stent thromboses, and mortality in patients with acute myocardial infarction undergoing reperfusion therapy. Although the prevailing view is that their benefit derives from their antithrombotic properties, other unrelated pleiotropic effects appear to be equally beneficial. Accumulating clinical and animal evidence indicates that, if present at the time of reperfusion, these drugs have a direct anti-infarct effect similar to that of ischemic postconditioning. Four oral antagonists have been developed in rapid succession: ticlopidine, clopidogrel, prasugrel, and ticagrelor. Each agent had a more consistent and rapid onset of action than the previous one, and this has correlated with improved clinical outcomes when given early in treatment. Unfortunately, gut absorption causes an appreciable delay in the onset of effect, especially when morphine is used, and the constant push to minimize the door-to-balloon time has made it difficult to achieve adequate platelet inhibition at the time of percutaneous coronary intervention with an oral agent. An intravenous P2Y12 antagonist such as cangrelor may optimize treatment because it produces nearly maximal inhibition of platelet aggregation within minutes. If antiplatelet agents do protect through postconditioning's mechanism, then they would render any other intervention that protects through that mechanism redundant. Indeed, animals treated with cangrelor cannot be further protected by pre- or postconditioning. However, interventions that use a different mechanism such as mild hypothermia or cariporide, a Na(+)-H(+) exchange blocker, do add to cangrelor's protection. Future research should be directed toward identifying interventions that can augment the protection from antiplatelet therapy and finding a way to optimize P2Y12 inhibition at reperfusion in all patients.

Effects of tirofiban maintenance duration on myocardial perfusion defect severity in anterior myocardial infarction

INTRODUCTION

Percutaneous coronary intervention (PCI) does not often produce optimal results, despite restoration of coronary blood flow at myocardial recovery, because of impaired microvascular perfusion. This study aimed to investigate and evaluate with (99m)Tc-sestamibi scan whether the results of PCI can be changed by maintenance infusion of tirofiban for 24 or 48 h in patients presenting with anterior ST-elevation myocardial infarction (STEMI).

METHODS

The study included 84 patients with anterior STEMI who were candidates for primary PCI and whose occlusion was in the proximal or mid-left anterior descending artery. Patients were given 25 μg/kg/3 min tirofiban and randomized to receive maintenance infusion at 0.15 μg/kg/min for 24 or 48 h. A resting (99m)Tc sestamibi scan was performed on the 5th day post-procedure before discharge. The primary efficacy endpoint was a patient's score on a 5-point scoring system for perfusion defect severity. Major adverse cardiac events (MACE) were defined as death from any cause, re-infarction, and clinically driven target-vessel revascularization within the first 6 months.

RESULTS

Baseline characteristics of the patients were similar in the two infusion groups (n = 42 per group). There was no significant difference in the symptom onset-to-presentation time or door-to-balloon time between the two groups. With the exception of basal anteroseptal and basal anterior segments, significant reductions were obtained on the 5-point scoring system for perfusion defect severity in segments and in the summed rest scores. No significant differences were observed between the two groups in the incidence of MACE at 6 months. The safety profile did not differ between 24 and 48 h infusions of tirofiban.

CONCLUSION

The use of tirofiban, when administered at a high bolus dose and maintained for 48 h, was safe and significantly reduced perfusion defect severity in patients with anterior STEMI presenting early after symptom onset and undergoing primary PCI.

Platelet P2Y₁₂ blockers confer direct postconditioning-like protection in reperfused rabbit hearts

BACKGROUND

Blockade of platelet activation during primary percutaneous intervention for acute myocardial infarction is standard care to minimize stent thrombosis. To determine whether antiplatelet agents offer any direct cardioprotective effect, we tested whether they could modify infarction in a rabbit model of ischemia/reperfusion caused by reversible ligation of a coronary artery.

METHODS AND RESULTS

The P2Y₁₂ (adenosine diphosphate) receptor blocker cangrelor administered shortly before reperfusion in rabbits undergoing 30-minute regional ischemia/3-hour reperfusion reduced infarction from 38% of ischemic zone in control hearts to only 19%. Protection was dose dependent and correlated with the degree of inhibition of platelet aggregation. Protection was comparable to that seen with ischemic postconditioning (IPOC). Cangrelor protection, but not its inhibition of platelet aggregation, was abolished by the same signaling inhibitors that block protection from IPOC suggesting protection resulted from protective signaling rather than anticoagulation. As with IPOC, protection was lost when cangrelor administration was delayed until 10 minutes after reperfusion and no added protection was seen when cangrelor and IPOC were combined. These findings suggest both IPOC and cangrelor may protect by the same mechanism. No protection was seen when cangrelor was used in crystalloid-perfused isolated hearts indicating some component in whole blood is required for protection. Clopidogrel had a very slow onset of action requiring 2 days of treatment before platelets were inhibited, and only then the hearts were protected. Signaling inhibitors given just prior to reperfusion blocked clopidogrel's protection. Neither aspirin nor heparin was protective.

CONCLUSIONS

Clopidogrel and cangrelor protected rabbit hearts against infarction. The mechanism appears to involve signal transduction during reperfusion rather than inhibition of intravascular coagulation. We hypothesize that both drugs protect by activating IPOC's protective signaling to prevent reperfusion injury. If true, patients receiving P2Y₁₂ inhibitors before percutaneous intervention may already be postconditioned thus explaining failure of recent clinical trials of postconditioning drugs.

A comparison between upfront high-dose tirofiban versus provisional use in the real-world of non-selected STEMI patients undergoing primary PCI: Insights from the Zwolle acute myocardial infarction registry

BACKGROUND

Despite the proven benefit of glycoprotein IIb/IIIa blockers in patients with acute ST-segment elevation myocardial infarction (STEMI), there is still debate on the timing of administration of these drugs and whether all or only a selection of patients should be treated. We evaluated the effect of routine upfront versus provisional use of high-dose tirofiban (HDT) in a large real-world population of non-selected STEMI patients.

METHODS

Consecutive STEMI patients were registered in a single-centre dedicated database. Patients with upfront HDT therapy before first balloon inflation were compared with patients who received the drug on a provisional basis, after first balloon inflation. Initial TIMI flow of the infarct-related vessel and enzymatic infarct size and 30-day clinical outcome were assessed.

RESULTS

Out of 2679 primary PCI patients HDT was given upfront in 885 (33.0%) and provisionally in 812 (45.3%). Upfront as compared with provisional HDT showed higher initial patency (22.3 vs. 17.9%, p=0.006), smaller infarct size (1401 IU/l (IQR 609 to 2948) vs. 1620 (753 to 3132), p=0.03) and a lower incidence of death or recurrent MI at 30 days (3.3 vs. 5.1%, p=0.04) without an increase in TIMI bleeding (p=0.24). Upfront HDT independently predicted initial patency (odds ratio (OR) 1.47, 95% confidence interval (CI) 1.15 to 1.88, p=0.02), enzymatic infarct size (OR 0.70, 95% CI 0.56 to 0.86, p=0.001) and 30-day death or recurrent MI (OR 0.59, 95% CI 0.37 to 0.95, p=0.03).

CONCLUSION

Our findings support the use of upfront potent antiplatelet and antithrombotic therapy in STEMI patients and encourage further clinical investigations in this field. (Neth Heart J 2010;18:592-7.).