A union in reperfusion: the concept of facilitated percutaneous coronary intervention

Percutaneous Mechanical Reperfusion During Acute Myocardial Infarction

The treatment of acute myocardial infarction has progressed from bedrest to mechanical, catheter-based reperfusion. The authors review the use of percutaneous coronary intervention (PCI) as a primary treatment for acute myocardial infarction and the use of adjunctive agents. The most recent American College of Cardiology/ American Heart Association (ACC/AHA) guidelines for the use of PCI in ST segment elevation myocardial infarction (MI) advocate the use of PCI as primary therapy at those centers in which the procedure can be performed within accepted standards. Because a majority of hospitals (80%) do not have the capability of performing primary PCI, most patients are treated with thrombolytic therapy. PCI should be considered in those patients treated with thrombolytic therapy who have persistent or recurrent ischemia and/or cardiogenic shock. For patients with non-ST elevation MI, the use of an invasive strategy (early angiography and PCI if needed) has recently shown to be beneficial. Although revascularization is the basis of the acute therapy of MI, additional pharmacologic therapy in the acute setting is now recognized as a key to favorable long-term outcome.

Actual Role of Platelet Glycoprotein IIb/IIIa Receptor Inhibitors as Adjunctive Pharmacological Therapy to Primary Angioplasty in Acute Myocardial Infarction: In the Light of Recent Randomized Trials and Observational Studies with Bivalirudin

Strategies for preventing ischemic complications during percutaneous coronary interventions (PCI) in the setting of acute myocardial infarction (AMI) have focused on the platelet surface-membrane glycoprotein (GP) IIb/IIIa receptor. The platelet GP IIb/IIIa receptor inhibitors, by blocking the final common pathway of platelet aggregation, have become a breakthrough in the management of acute coronary syndromes. Current adjuvant pharmacological therapy of AMI with aspirin, clopidogrel, unfractionated heparin (UH), and platelet GP IIb/IIIa inhibitors provides useful therapeutic benefits. Although the use of more potent antithrombin and antiplatelet agents during PCI in AMI has reduced the rate of ischemic complications, in parallel, the rate of bleeding has increased. Several studies have reported an association between bleeding after PCI and an increase in morbidity and mortality. Therefore, investigational studies have focused in pharmacological agents that would reduce bleeding complications without compromising the rate of major adverse cardiovascular events. Based on the results of several randomized trials, abciximab with UH, aspirin and clopidogrel have become a standard adjunctive therapy with primary PCI for AMI. However, some of the trials were done before the use of stents and the widespread use of thienopyridines. In addition, GP IIb/IIIa inhibitors use have been associated with thrombocytopenia, high rates of bleeding, and the need for transfusions, which increase costs, length of hospital stay, and mortality. On the other hand, in the stent era, bivalirudin, a semi-synthetic direct thrombin inhibitor, has recently been shown to provide similar efficacy with less bleeding compared with unfractionated heparin plus platelet GP IIb/IIIa inhibitors in AMI patients treated with primary PCI. The impressive results of this recent randomized trial and other observational studies make a strong argument for the use of bivalirudin rather than heparin plus GP IIb/IIIa inhibitors for the great majority of patients with AMI treated with primary PCI. However, some controversial results and limitations in the studies with bivalirudin exert some doubts in the future widespread use of this drug.

Operator volume and outcomes of primary angioplasty for acute myocardial infarction in a single high-volume centre

OBJECTIVE

The guidelines for the management of ST-elevation myocardial infarction (STEMI) state the minimum operator volume for percutaneous coronary interventions (PCIs), without strong evidence of a relationship between operator volume and outcomes of primary angioplasty, at variance with elective practice. We sought to investigate the effect of operator volume on primary PCI for STEMI.

METHODS

Three hundred and thirty-one consecutive STEMI patients were treated over 19 months with primary PCI in a high-volume centre without on-site cardiac surgery. Three skilled operators, with very different volumes of interventional practice, performed the PCI procedures around-the-clock.

RESULTS

Operators were divided into very high (A), intermediate high (B) and low high volume (C). Demographic, clinical, angiographic, and procedural characteristics of the patient population did not differ among operators, with the exception of three-vessel disease (P = 0.016), circumflex infarct-related artery (P = 0.002), mechanical support (P = 0.02), use of abciximab (P = 0.003) for operator C, use of tirofiban for operator B (P = 0.02), and type of stent for operator A (P = 0.0004). Similarly, no differences were observed among operators in in-hospital outcomes (death, a composite of major adverse cardiovascular events, ST-segment resolution, thrombolysis in myocardial infarction flow grade 3, length of hospitalization) and haemorrhagic complications.

CONCLUSIONS

Our data show that there is not a significant relationship between operator volume over the threshold indicated by the guidelines, and both primary PCI early outcomes and complications in STEMI, and suggest that expertise and experience of the whole professional team rather than just of the individual operator play a major role.

Time to treatment and ST-segment resolution in high-risk patients with acute myocardial infarction transferred from community hospitals for coronary angioplasty after pharmacological treatment

OBJECTIVE

To evaluate the impact of symptom-onset-to-balloon delay on ST-segment resolution (STR) in patients with acute myocardial infarction transferred from community hospitals for angioplasty after pharmacological treatment. The study design was prospective, single centre registry.

METHODS

Between October 2000 and December 2003, 330 consecutive patients aged < or =75 years with high-risk myocardial infarction were considered; 193 patients underwent primary percutaneous coronary intervention (PCI) (group P), whereas 137 patients were given pharmacological therapy and were immediately transferred to the hospital with PCI facilities (group F).

RESULTS

Compared with group P, group F showed a longer time to treatment (253 +/- 136 vs. 195 +/- 141 min; P < 0.0001) and a higher percentage of Thrombolysis In Myocardial Infarction flow grade 2-3 at pre-PCI angiography (107 [78.1%] vs. 48 [24.8%]; P < 0.0001). The rate of STR > or =70% was similar in groups P and F (121 [62.7%] vs. 94 [68.6%]; P = 0.41). Even after accounting for baseline variables, STR <70% was not significantly related to the transfer strategy (adjusted hazard ratio 0.94, 95% confidence interval 0.94-1.77; P = 0.8). Patients with incomplete STR showed a higher six-month mortality compared with patients with complete STR (10 [8.85%] vs. 6 [2.76%]; P = 0.027).

CONCLUSIONS

The STR index predicts survival in patients with ST-elevation myocardial infarction treated with angioplasty either directly or after pharmacological treatment and hospital transfer. Pharmacological facilitation seems to be able to counterbalance the negative consequences of the transfer-related time delay on myocardial reperfusion as evaluated by the STR index.

Relation of pain-to-balloon time and myocardial infarct size in patients transferred for primary percutaneous coronary intervention

The paradigm of a shorter pain-to-balloon time decreasing extent of infarct size may be not completely true in transferred patients. This study evaluated the influence of pain-to-balloon time on infarct size as assessed by delayed enhancement magnetic resonance imaging in patients transferred from a peripheral hospital to a tertiary center for primary coronary angioplasty (percutaneous coronary intervention [PCI]). Sixty patients (40 men, 64 +/- 3 years of age) with first acute myocardial infarction were treated within <168, 168 to 222, 223 to 300, and >300 minutes. A presentation score system including clinical, laboratory, and echocardiographic data was used to classify severity of presentation at admission. Magnetic resonance imaging was performed 6 +/- 3 days after PCI. Group 1 had a higher presentation score than did group 2 (p <0.02) and group 3 (p <0.02). Group 1 had a significantly longer delayed enhancement than did group 2 (p <0.002) and group 3 (p <0.03). In conclusion we found that patients with worse presentation are transferred sooner for primary PCI. This approach in these patients does not decrease infarct size likely because of unavoidable delay to reperfusion. This finding suggests a different therapeutic strategy in these patients.

Facilitated Percutaneous Coronary Intervention

The goal of the initial treatment for ST-segment elevation myocardial infarction is rapid and effective reperfusion. Randomized trials have demonstrated that primary angioplasty is preferred over thrombolysis if done in a timely manner and by an experienced team. However, due to many factors, performance of primary angioplasty within the goal of 90 min is often not possible. A combined strategy of immediate thrombolysis in the emergency room or in the ambulance followed by angioplasty theoretically could provide early reperfusion with subsequent angioplasty to insure complete reperfusion. Over 17 clinical trials have been reported. Compared with thrombolysis, facilitated angioplasty in the most recent trials has been shown to have a more favorable long-term outcome. Trials comparing facilitated angioplasty with full- or half-dose thrombolysis versus primary angioplasty have been far less favorable with the largest trial to date, the ASSENT (Assessment of the Safety and Efficacy of a New Treatment Strategy with Percutaneous Coronary Intervention)-4 trial, demonstrating a worse outcome in the primary end point of death, congestive heart failure, or shock at 90 days. Pending the results of the FINESSE (Facilitated Intervention with Enhanced Reperfusion Speed to Stop Events) trial, current data suggest that facilitated angioplasty does not offer any advantage over primary angioplasty and may be harmful.

Is delayed facilitated percutaneous coronary intervention better than immediate in reperfused myocardial infarction? Six months follow up findings

BACKGROUND

There are several new strategies proposed to improve the outcome of patients with ST-elevation myocardial infarction (STEMI). One approach is the resurgent use of facilitated percutaneous coronary interventions (PCI). Until recently, deciding whether immediate PCI after combined treatment (facilitated PCI) is more appropriate than delayed PCI (short time) has not been investigated. The aim of this study, therefore, was to investigate the outcomes in patients initially successfully treated pharmacologically and immediate PCI < 2 hr, and in patients initially successfully treated with pharmacological therapy and with delayed PCI (12-72 h).

METHODS

451 reperfused STEMI patients, aged 18 to 75 years, class I-II Killip, with an acceptable echocardiographic window and admitted within 12 hs of the onset of symptoms were randomized into two groups. All patients had to have successful reperfusion, to receive the combination of a standard tirofiban infusion or abciximab plus half dose rtPA. Thereafter, patients were sub-grouped as follows:group 1 (immediate PCI) patients had PCI within 2 h; and group 2 (delayed PCI) patients in which PCI was performed after 12 hs and within 72 hs.

RESULTS

The 225 reperfused (immediate-PCI) and 226 reperfused (delayed-PCI) patients (time from randomization to PCI 165 +/- 37 min in immediate PCI versus 45.1 +/- 20.2 h in delayed PCI group) showed similar results in ejection fraction, CK release and patency of the IRA. In addition, the delayed PCI group showed a significant reduction in ischemic events, restenosis and bleedings (P = 0.005, 0.01, 0.01 respectively) and significant reduced angiographic evidence of thrombus formation in the infarction-related artery (IRA) (p = 0.001).

CONCLUSION

Our data suggest the safety and possible use of delayed facilitated PCI in patients with STEMI, and that delayed PCI in patients treated with combined lytic and IIb/IIIa inhibitors appears to be as effective and possibly superior (reduced ischemic events and repeat PCI) as immediate PCI. The patients in this study were successfully reperfused, with TIMI-3 flow and our data may not apply to patients with TIMI 0-2 flow. This strategy could allow transferring the reperfused patients and performing PCI after hours < 72 hours and not immediately, thereby reducing the number of urgent PCI and costs, obtaining similar results, but mostly causing less discomfort to the patient. Our results had to be interpreted with caution, because current guidelines do not recommend the combined therapy, but suggest further studies. The study was aimed to investigate the outcomes in patients initially successfully treated pharmacologically and immediate PCI < 2 h, and in patients initially successfully treated with pharmacological therapy and delayed PCI (12-72 h). All patients had to have successful reperfusion, to receive the combination of a standard abciximab or tirofiban infusion plus half dose rtPA. Similar results were observed in both groups. Delayed PCI group showed a significant lower incidence in restenosis (0.01), minor bleedings (0.005), ischemic events (0.01) and a reduced angiographic evidence of thrombus formation in IRA (0.001). Our data suggest the safety and possible use of delayed facilitated PCI in patients with STEMI. Our results had to be interpreted with caution, because current guidelines do not recommend the combined therapy, but suggest further studies.

Immediate versus delayed facilitated percutaneous coronary intervention: a pilot study

The study was aimed to investigate the outcomes in patients initially successfully treated pharmacologically and immediate PCI <2 hours, and in patients initially successfully treated with pharmacological therapy and delayed PCI (12-72 hours). All patients had to have successful reperfusion, to receive the combination of a standard abciximab infusion plus half dose rtPA. Similar results were observed in both groups. Delayed PCI group showed a favorable trend in restenosis and bleedings (ns) and a significant reduced angiographic evidence of thrombus formation in IRA. Our very preliminary data suggest the safety and possible use of delayed facilitated PCI in patients with STEMI. The studied patients have successful reperfusion and TIMI-3 flow and our data may not apply to patients with TIMI 0-2 flow.

Early versus periprocedural administration of abciximab for primary angioplasty: a pooled analysis of 6 studies

BACKGROUND

The 2004 ACC/AHA guidelines on ST-elevation myocardial infarction state that it is reasonable to start treatment with abciximab as early as possible before primary percutaneous coronary intervention (PCI). We investigated the potential benefit of early use of abciximab by pooling data from all the available studies.

METHODS

Six prospective studies were identified that had allocated 260 patients to receive early abciximab (either prehospital or soon after the patient arrived in hospital) and 342 to receive late abciximab (at the time of PCI).

RESULTS

TIMI flow grade 2 or 3 was present in 42% of the early group compared with 29% in the late group (P = .001). After PCI, 59% of patients in the early group showed ST-resolution >or = 70%, compared with 41% in the late group (P = .003). The composite clinical outcomes death, new myocardial infarction, or repeat target vessel revascularization at 30 days occurred in 7.3% of the early group compared with 9.7% in the late group (odds ratio 0.73, 95% CI 0.41-1.32) and death alone occurred in 2.7% versus 4.7%, respectively (odds ratio 0.56, 95% CI 0.23-1.39).

CONCLUSIONS

Early administration of abciximab improves epicardial patency (TIMI flow) before PCI and results in better myocardial tissue perfusion (ST-resolution) after the procedure. The promising effects on clinical outcomes need to be tested in larger studies.

Facilitated percutaneous coronary intervention: is this strategy ready for implementation?

Reperfusion therapy with pharmacologic fibrinolysis has provided striking reductions in mortality following acute ST-elevation myocardial infarction (STEMI). Nevertheless, the limitations of fibrinolysis are well recognized. Attempts to improve reperfusion with bolus-only fibrinolysis, and combination regimens including enoxaparin and glycoprotein IIb/IIIa inhibition have not led to improvements in mortality. Although both prehospital fibrinolysis and primary percutaneous coronary intervention (PCI) have reduced mortality, these strategies are associated with considerable logistic constraints, hampering widespread implementation. Potentially, a hybrid strategy combining the speed and simplicity of pharmacologic reperfusion with the ability to ensure epicardial vessel patency, and providing definitive management of the culprit lesion remains an attractive option. Facilitated PCI for STEMI may extend the benefit of myocardial reperfusion to a greater number of patients. The true benefit of this strategy will be defined by ongoing large-scale clinical trials. If results are positive, the clinical practice determinants required for the effective application of this strategy to the wider clinical community will need careful consideration.

Improved speed and stability of ST-segment recovery with reduced-dose tenecteplase and eptifibatide compared with full-dose tenecteplase for acute ST-segment elevation myocardial infarction

OBJECTIVES

This sub-study of the Integrilin and Tenecteplase in Acute Myocardial Infarction (INTEGRITI) trial evaluated of the impact of combination reperfusion therapy with reduced-dose tenecteplase plus eptifibatide on continuous ST-segment recovery and angiographic results.

BACKGROUND

Combination therapy with reduced-dose fibrinolytics and glycoprotein IIb/IIIa inhibitors for ST-segment elevation myocardial infarction improves biomarkers of reperfusion success but has not reduced mortality when compared with full-dose fibrinolytics.

METHODS

We evaluated 140 patients enrolled in the INTEGRITI trial with 24-h continuous 12-lead ST-segment monitoring and angiography at 60 min. The dose-combination regimen of 50% of standard-dose tenecteplase (0.27 microg/kg) plus high-dose eptifibatide (2 boluses of 180 microg/kg separated by 10 min, 2.0 microg/kg/min infusion) was compared with full-dose tenecteplase (0.53 microg/kg).

RESULTS

The dose-confirmation regimen of reduced-dose tenecteplase plus high-dose eptifibatide was associated with a faster median time to stable ST-segment recovery (55 vs. 98 min, p = 0.06), improved stable ST-segment recovery by 2 h (89.6% vs. 67.7%, p = 0.02), and less recurrent ischemia (34.0% vs. 57.1%, p = 0.05) when compared with full-dose tenecteplase. Continuously updated ST-segment recovery analyses demonstrated a modest trend toward greater ST-segment recovery at 30 min (57.7% vs. 40.6%, p = 0.13) and 60 min (82.7% vs. 65.6%, p = 0.08) with this regimen. These findings correlated with improved angiographic results at 60 min.

CONCLUSIONS

Combination therapy with reduced-dose tenecteplase and eptifibatide leads to faster, more stable ST-segment recovery and improved angiographic flow patterns, compared with full-dose tenecteplase. These findings question the relationship between biomarkers of reperfusion success and clinical outcomes.

Combined fibrinolysis using reduced-dose alteplase plus abciximab with immediate rescue angioplasty versus primary angioplasty with adjunct use of abciximab for the treatment of acute myocardial infarction: Asia-Pacific Acute Myocardial Infarction Trial (APAMIT) pilot study

We conducted a randomized feasibility pilot study comparing combined fibrinolysis with immediate rescue angioplasty vs. primary angioplasty with adjunctive abciximab in patients with acute myocardial infarction (AMI). Seventy patients with ST segment elevation AMI of </= 6 hr were randomized to either 50 mg of alteplase and abciximab (n = 34) or primary angioplasty with adjunctive abciximab (n = 36). Coronary angiography was performed at 60 min in the combined lytic group and TIMI 3 flow was present in 65% of patients as compared to 25% (P = 0.001) in the primary angioplasty group prior to intervention. Treatment success, defined as TIMI 3 flow, was achieved in 83% of patients in the primary angioplasty group (P = 0.075 compared to 65% in combined lytic group before rescue angioplasty). There was no difference in overall treatment success between primary angioplasty and combined lytic group with rescue angioplasty (83% vs. 94%; P = NS). Major adverse cardiac events at 1 month were not significant (15% vs. 11%; P = NS), but there was a trend toward more events in the combined lytic group at 6 months (32% vs. 14%; P = 0.066), particularly in target vessel revascularization. In this feasibility pilot study, high rate of TIMI 3 flow was attained in patients with AMI with both combined fibrinolysis and primary angioplasty with adjunctive abciximab. A larger randomized trial is currently ongoing to compare these two strategies.

Reperfusion in acute myocardial infarction: current concepts

Myocardial reperfusion is the treatment of choice in acute myocardial infarction. Pharmacological thrombolysis restores coronary artery patency in about two thirds of patients with acute myocardial infarction. However, mechanical reperfusion with primary angioplasty and stenting achieves higher patency rates with less complications, especially in high-risk patients. Adjunctive pharmacotherapy and new device technology may improve the outcome of primary angioplasty. Facilitated angioplasty using a combination of half-dose thrombolysis, platelet glycoprotein IIb/IIIa antagonists, and early intervention, appears to be a promising strategy for the treatment of acute myocardial infarction in the modern era. The efficacy and safety of this approach are currently evaluated in several ongoing trials.

Pharmacologic reperfusion therapy for acute myocardial infarction

Acute myocardial infarction (MI) remains a significant problem in terms of morbidity, mortality and healthcare costs. Pharmacologic reperfusion therapies for MI are becoming increasingly complex. This review therefore places contemporary pharmacologic MI developments into perspective. An historical overview of pharmacologic reperfusion therapy for MI is provided, followed by an analysis of current limitations, treatment options, and present and likely future pharmacologic therapies. Adjunctive percutaneous and other treatments are also discussed, to clarify what is becoming a rapidly changing field.