Reappraising the role of immediate intervention following thrombolytic recanalization in acute myocardial infarction

Early invasive versus conservative treatment in patients with failed fibrinolysis--no late survival benefit: the final analysis of the Middlesbrough Early Revascularisation to Limit Infarction (MERLIN) randomized trial

BACKGROUND

Early (30 days) and midterm (6 months) clinical outcomes in trials comparing rescue angioplasty (rescue percutaneous coronary intervention [rPCI]) with conservative treatment of failed fibrinolysis complicating ST-segment elevation myocardial infarction have shown variable results. Whether early rPCI confers late (up to 3 years) clinical benefits is not known.

METHODS

The MERLIN trial compared rPCI and a conservative strategy in patients with failed fibrinolysis complicating ST-segment elevation myocardial infarction. Three hundred seven patients with electrocardiographic evidence of failure to reperfuse at 60 minutes were included. Patients in cardiogenic shock were excluded. Thirty-day and 1-year results have been reported. Results of 3 years of follow-up are presented.

RESULTS

Three-year mortality in the conservative arm and rPCI, respectively, was 16.9% versus 17.6% (P = .9, relative difference [RD] -0.8, 95% CI [-9.3 to 7.8]). Death rates were similar (3.9% vs 3.2%) between 1- and 3-year follow-up, respectively. The incidence of the composite secondary end point of death, reinfarction, stroke, unplanned revascularization, or heart failure was significantly higher in the conservative arm (64.3% vs 49%, P = .01, RD 15.3, 95% CI [4.2-26]). There was no significant difference in the rate of reinfarction (0.7% vs 0.7%) or heart failure (1.3% vs 2.7%) between 1 and 3 years between the conservative and rPCI arms, respectively. The incidence of subsequent unplanned revascularization at 3 years was significantly higher in the conservative arm (33.8% vs 14.4%, P < .01, RD 19.4, 95% CI [10-28.7]), most of which occurred within 1 year; the rates between 1 and 3 years were 3.9% in the conservative arm versus 2% in the rPCI arm. There was a trend toward fewer strokes in the conservative arm at 3 years (conservative arm 2.6% vs rPCI 6.5%, P = .1, RD -3.9%, 95% CI [-9.4 to 0.8]), with similar stroke rates (1.3% vs 1.3%) between 1- and 3-year follow-up.

CONCLUSIONS

Rescue angioplasty did not confer a late survival advantage at 3 years. The composite end point occurred less often in the rPCI arm mainly because of fewer unplanned revascularization procedures in the early phase of follow-up. The highest risk of clinical events in patients with failed reperfusion is in the first year, beyond which the rate of clinical events is low.

Immediate angioplasty after thrombolysis: a systematic review

BACKGROUND

The role of immediate transfer for percutaneous coronary intervention (PCI) after thrombolysis for ST-segment elevation myocardial infarction remains controversial. We performed a systematic review of the related literature to determine whether thrombolysis followed by transfer for immediate or early PCI is safe, feasible and superior to conservative management.

METHODS

A systematic literature search of MEDLINE, EMBASE, the Cochrane Database for Systematic Reviews and Cochrane Central Register of Controlled Trials, and the American Heart Association EndNote 7 Master Library databases, was performed to 2004 for relevant published studies. The level of evidence and the quality of the study design and methods were rated by 2 reviewers according to a standardized classification. A quantitative meta-analysis was performed to assess the effect at 6-12 months on mortality of immediate or early PCI after thrombolysis.

RESULTS

We found 13 articles that were supportive of immediate or early PCI after thrombolysis and 16 that were neutral or provided evidence opposing it. The largest randomized trials and meta-analyses showed no benefit of routine PCI immediately or shortly after thrombolysis. The studies that were supportive were generally more recent and more frequently involved coronary stents. One large trial supported early PCI after thrombolysis for patients with myocardial infarction complicated by cardiogenic shock. Overall, the difference in mortality rates between the invasive strategy and conservative care was nonsignificant. The 3 stent-era trials showed a significantly lower mortality among patients randomly assigned to the invasive strategy (5.8% v. 10.0%, odds ratio 0.55, 95% confidence interval 0.32-0.92). Analysis of variance found a significant difference in treatment effect between stent-era and pre-stent-era trials.

INTERPRETATION

At present, there is inadequate evidence to recommend routine transfer of patients for immediate or early PCI after successful thrombolysis. Results of recent trials using contemporary PCI techniques, including coronary stents, appear more favourable but need to be confirmed in large randomized trials, which are currently in progress. Transfer for immediate PCI is recommended for patients with cardiogenic shock, hemodynamic instability or persistent ischemic symptoms after thrombolysis.

One year results of the Middlesbrough early revascularisation to limit infarction (MERLIN) trial

OBJECTIVE

To report one year results of the MERLIN (Middlesbrough early revascularisation to limit infarction) trial, a prospective randomised trial comparing the strategy of coronary angiography and urgent revascularisation with conservative treatment in patients with failed fibrinolysis complicating ST segment elevation myocardial infarction (STEMI). The 30 day results have recently been published. At the planning stage of the trial, it was determined that follow up of trial patients would continue annually to three years to determine whether late benefit occurred.

SUBJECTS

307 patients who received a fibrinolytic for STEMI but failed to reperfuse early according to previously described ECG criteria and did not develop cardiogenic shock.

METHODS

Patients were randomly assigned to receive either emergency coronary angiography with a view to proceeding to urgent revascularisation (rescue percutaneous coronary intervention (rPCI) arm) or continued medical treatment (conservative arm). The primary end point was all cause mortality at 30 days. The secondary end points included the composite end point of death, reinfarction, stroke, unplanned revascularisation, or heart failure at 30 days. The same end points were evaluated at one year and these results are presented.

RESULTS

All cause mortality at one year was similar in the conservative arm and the rPCI arm (13.0% v 14.4%, p = 0.7, risk difference (RD) -1.4%, 95% confidence interval (CI) -9.3 to 6.4). The incidence of the composite secondary end point of death, reinfarction, stroke, unplanned revascularisation, or heart failure was significantly higher in the conservative arm (57.8% v 43.1%, p = 0.01, RD 14.7%, 95% CI 3.5% to 25.5%). This was driven almost exclusively by a significantly higher incidence of subsequent unplanned revascularisation in the conservative arm (29.9% v 12.4%, p < 0.001, RD 17.5%, 95% CI 8.5% to 26.4%). Reinfarction and clinical heart failure were numerically, but not statistically, more common in the conservative arm (14.3% v 10.5%, p = 0.3, RD 3.8%, 95% CI -3.7 to 11.4, and 31.2% v 26.1%, p = 0.3, RD 5.0%, 95% CI -5.1 to 15.1). There was a strong trend towards fewer strokes in the conservative arm (1.3% v 5.2%, p = 0.06, RD -3.9%, 95% CI -8.9 to 0.06).

CONCLUSION

At one year of follow up, there was no survival advantage in the rPCI arm compared with the conservative arm. The incidence of the composite secondary end point was significantly lower in the rPCI arm, but this was driven almost entirely by a highly significant reduction in the incidence of further revascularisation.

Small molecule glycoprotein IIb/IIIa receptor inhibitors as upstream therapy in acute coronary syndromes: insights from the TACTICS TIMI-18 trial

Glycoprotein (GP) IIb/IIIa inhibitors are beneficial in unstable angina/non-ST-segment elevation myocardial infarction (UA/NSTEMI). In large trials, the GP IIb/IIIa inhibitors tirofiban and eptifibatide were each found to reduce the risk of death or myocardial infarction (MI) in these patients at 30 days. These agents appear to be of greatest benefit in patients with a positive troponin at baseline, diabetes or ST-segment depression, recurrent angina, prior aspirin use, or a Thrombolysis In Myocardial Infarction (TIMI) risk score > or = 4. The Treat angina with Aggrastat and determine Cost of Therapy with an Invasive or Conservative Strategy (TACTICS) TIMI-18 trial was designed to compare the benefits of an early invasive versus a conservative strategy in high-risk UA/NSTEMI patients treated with GP IIb/IIIa inhibition. Patients were treated with tirofiban (for 48 h) plus aspirin and heparin and randomized to either invasive therapy (coronary angiography and revascularization when feasible) or conservative treatment (angiography only for patients with recurrent ischemia at rest or a positive stress test). A significant reduction in death or MI was demonstrated at 30 days (p = 0.02) and at 6 months (p = 0.0498). Death, MI, or rehospitalization for an acute coronary syndrome was also reduced with the invasive therapy at six months (p = 0.025). These results provide evidence to physicians that early GP IIb/IIIa inhibition in combination with a prompt invasive approach should be used more widely in UA/NSTEMI patients, particularly those at high risk.

Large intracoronary thrombi with good TIMI flow during acute myocardial infarction: four cases of successful aggressive medical management in patients without angiographically detectable coronary atherosclerosis

Four cases of young patients with acute myocardial infarction are discussed in which urgent angiography showed large intracoronary thrombus and TIMI (thrombolysis in myocardial infarction) flow > or = 2 in the infarct related artery. The rest of the coronary tree appeared to be free of detectable atherosclerosis. Percutaneous transluminal coronary angioplasty was not performed and an aggressive antiplatelet/anticoagulant treatment was administered (acetylsalicylic acid, clopidogrel, abciximab, and heparin). In all cases early angiographic control (1-12 days after AMI) showed disappearance of thrombus, no significant residual stenosis, and normal flow. No deterioration of left ventricular function was observed and the clinical course both in hospital and at five months' follow up was uneventful.

Keeping the coronary arteries open: current opportunities

Thrombolysis has reduced mortality from myocardial infarction, but effective opening of the artery with normal flow continues to be an important goal. Thrombolysis is not always as successful as it should be; alternatives include adjunctive therapy and mechanical opening of the arteries. In patients with acute coronary occlusion opening the artery should continue to be the primary aim.

Determinants and prognostic significance of spontaneous coronary recanalization in acute myocardial infarction

Spontaneous recanalization (SR) occurs after the onset of acute myocardial infarction (AMI), but its clinical significance in the reperfusion era remains uncertain. We evaluated the determinants and prognostic significance of SR in 196 consecutive patients with AMI who underwent primary angioplasty at our institution. The study population was divided into 2 groups according to the presence (group I, n = 44) or absence (group II, n = 152) of SR (Thrombolysis In Myocardial Infarction [TIMI] anterograde > or = 2 flow on the preintervention angiogram). The primary end point was the occurrence, within 6-weeks after AMI, of death, nonfatal reinfarction, and congestive heart failure. Baseline characteristics were similar between the 2 groups. Peak levels of creatine kinase were lower in group I than in group II (2,500 +/- 1,800 vs 4,000 +/- 2,900 U/L, respectively, p < 0.05). The rate of TIMI flow grade 3 after intervention was higher in group I than in group II (93.2% vs 79.6%, respectively, p < 0.05), and patients in group I had a faster corrected TIMI frame count than those in group II (22.7 +/- 12.4 vs 30.3 +/- 22.8, respectively, p < 0.05). Preinfarction angina (odds ratio [OR] 2.18, 95% confidence interval [CI] 1.10 to 4.33, p < 0.05), heavy thrombi (OR 0.10, 95% CI 0.01 to 0.74, p < 0.05), and good angiographic collaterals (OR 0.12, 95% CI 0.02 to 0.89, p < 0.05) were independent predictors of SR. Death, reinfarction, and severe arrhythmia were not different between the 2 groups. However, heart failure occurred more frequently in group II than in group I (15.1% vs 2.3%, respectively, p < 0.05). The primary end point was also significantly lower in group I than in group II (4.5% vs 18.4%, respectively, p < 0.05). In conclusion, SR in AMI is associated with faster coronary flow, smaller infarct size, and a better clinical outcome after primary angioplasty.