Mechanical reperfusion therapy for acute myocardial infarction: Stent PAMI, ADMIRAL, CADILLAC and beyond

Rescue percutaneous coronary intervention for failed thrombolysis

BACKGROUND

Previous studies of rescue percutaneous coronary intervention (PCI) for failed thrombolysis yielded conflicting results. In the current era of newer thrombolytic agents, coronary stents, glycoprotein IIb/IIIa inhibitors, and aggressive hemodynamic support, the outcome of this high-risk patient group has not been characterized.

METHODS

From January 2000 to October 2004, 214 consecutive patients were transferred and underwent emergent coronary angiography following failed thrombolysis. One hundred and fifty five (72%) underwent immediate PCI, 23 (11%) underwent delayed PCI, and 36 (17%) received surgical revascularization or medical therapy. Medical records and angiograms for the entire PCI cohort (n=178) were reviewed for in-hospital events including bleeding complications, stroke, recurrent ischemia or myocardial infarction (MI), target vessel revascularization (TVR), and death.

RESULTS

Time from symptom onset to thrombolysis (mean +/- standard deviation) was 5.6 +/- 11.9 hr, and time from thrombolysis to angiography was 7.0 +/- 5.5 hr. The study cohort was critically ill, with 9.6% experiencing cardiac arrest, 21% in cardiogenic shock, and 12% intubated prior to transfer. Coronary stents were placed in 88%, Rheolytic thrombectomy was used in 21%, an intraaortic balloon pump was placed in 17%, and a glycoprotein IIb/IIIa inhibitor was administered in 92%. Patients receiving delayed PCI had higher TIMI 3 flow grade at initial angiography than those receiving immediate PCI (83% vs. 34%, respectively, P < 0.0001). Angiographic success was 90% for the entire PCI cohort, 89% for the immediate PCI group, and 100% for the delayed PCI group. Clinical success (angiographic success and freedom from major adverse cardiac events) was 85% for the entire PCI cohort, 83% for the immediate PCI group, and 100% for the delayed PCI group. Severe and moderate bleeding complications occurred in 7.3%, stroke in 1.7%, recurrent ischemia or MI in 7.3%, and TVR in 3.4%. Overall, in-hospital mortality for the entire PCI cohort was 3.4%.

CONCLUSIONS

This observational, consecutive, real-world study of contemporary rescue PCI for failed thrombolysis shows a high use of coronary stents, Rheolytic thrombectomy, glycoprotein IIb/IIIa inhibitors, and intraaortic balloon pump placement. Angiographic and clinical success was high with low bleeding complications and low in-hospital mortality, suggesting that prospective, randomized trials using contemporary interventional therapy for rescue PCI be considered.

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.

Interaction between arrival time and thrombolytic treatment in determining early outcome of acute myocardial infarction

BACKGROUND

Shortening prehospital delay has been identified as an important means of improving responses to reperfusion treatment. If this increases the risk profile of the population delivered to hospital, it may paradoxically cause a deterioration in hospital mortality.

OBJECTIVE

To examine the interaction between arrival time (time from onset of chest pain to arrival at hospital) and thrombolytic treatment in determining the early outcome of acute myocardial infarction.

METHODS

Prospective cohort study of 1723 patients with acute myocardial infarction who were potentially eligible for thrombolytic treatment (ST elevation on ECG; arrival time < or = 12 hours).

RESULTS

All patients were eligible for thrombolysis but only 1098 (80%) received it. Patients who did not receive thrombolytic treatment were older (66 (58-73) v 61 (53-70) years, p < 0.001), more commonly female (32.1% v 24.8%, p < 0.01), and had higher frequencies of previous infarction (28.6% v 15.6%, p < 0.001) and left ventricular failure (37.5% v 26.9%, p < 0.01) than patients who received thrombolytic treatment. For the group as a whole, 30 day mortality was 11.7% and was unaffected by arrival time, but in patients who did not receive thrombolysis an arrival time of < or = 6 hours was associated with significantly higher 30 day mortality than an arrival time of 6-12 hours (24.3% v 2.6%, p = 0.002). Conversely, in patients who did receive thrombolysis an arrival time of < or = 6 hours was associated with a lower 30 day mortality than an arrival time of 6-12 hours (8.5% v 14.5%, p < 0.02).

CONCLUSIONS

Shortening prehospital delay in acute myocardial infarction will tend to increase the risk profile of patients presenting to emergency departments. The data presented here indicate that this may increase hospital mortality if underutilisation of thrombolytic treatment among high risk groups is not diminished.