Primary angioplasty and thrombolysis for acute myocardial infarction: an evidence summary

Economic evidence of interventions for acute myocardial infarction: a review of the literature

AIMS

The aims of this review are to identify and evaluate studies exploring the cost-effectiveness of primary angioplasty (PPCI) vs. thrombolysis (TL) for treating acute myocardial infarction (AMI).

METHODS AND RESULTS

A comprehensive free-text searching identified economic evaluation studies that were reviewed with respect to their effectiveness data, identification, measurement and valuation of resource data, measurement and valuation of health outcomes (clinical and QALYs) and uncertainty analysis. A total of 14 studies were included in the review: seven were economic evaluations alongside RCTs, two community-based studies or registries and five decision-analytical models. PPCI was found to be cost-effective when compared with TL in eight studies, cost-saving in three, cost-neutral in one, and not significantly different in terms of both cost and benefits in two studies.

CONCLUSIONS

The cost-effective evidence available is mainly derived from RCTs with stringent inclusion criteria using established catheter laboratories for providing PPCI treatment; these two components might restrict the generalisability of their "for managing patients with STEMI in hospital" settings. In order to aid policy makers on the real costs and benefits of the PPCI and TL, it is necessary to conduct more analyses with data from the real world in which there are more strategies evaluated for delivering PPCI than merely those in established catheter laboratories.

Delays in fibrinolysis as primary reperfusion therapy for acute ST-segment elevation myocardial infarction

BACKGROUND

In contemporary practice, the degree to which fibrinolytic therapy is administered in a timely fashion for ST-segment elevation myocardial infarction (STEMI) and its association with outcomes is not well-known. Our objective was to assess the performance of fibrinolytic therapy within the recommended 30-minute time frame for patients with STEMI.

METHODS

Patient characteristics associated with the timeliness of fibrinolytic therapy were evaluated. We also examined the association of timely fibrinolysis with key patient outcomes, including inpatient mortality, stroke, and cardiogenic shock. Logistic generalized estimating equations were used to account for baseline clinical factors and within-hospital clustering.

RESULTS

Between January 2007 and June 2008, 3,219 STEMI patients in 178 hospitals received primary fibrinolytic therapy. Median door-to-needle (DTN) time was 34.0 minutes (interquartile range 22.0-54.0 minutes). However, only 44.5% met the American College of Cardiology/American College of Cardiology guideline DTN time of < or =30 minutes. Patient characteristics associated with longer fibrinolysis times included female gender (+17.8% longer vs men, 95% CI 11.9-24.1) and age > or =75 (+12.0% longer vs age <55, 95% CI 1.8-23.2). Timely (vs delayed) fibrinolysis was associated with a decreased risk of a composite outcome of death, shock, or stroke (6.2% vs 8.8%, adjusted odds ratio 0.74, 95% CI 0.56-0.98).

CONCLUSIONS

Timely fibrinolytic therapy was associated with lower risk of a composite outcome of shock, death, or stroke, yet DTN times of < or =30 minutes were achieved in less than half of the patients studied. Thus, efforts to optimize regional systems of STEMI care should focus on shortening reperfusion times for patients who receive fibrinolysis, as well as those who receive primary percutaneous coronary intervention.

Alternative pay-for-performance scoring methods: implications for quality improvement and patient outcomes

BACKGROUND

Pay-for-performance programs typically rate hospitals using a composite summary score in which process measures are weighted by the total number of treatment opportunities. Alternative methods that weight process measures according to how hospitals organize care and the range for possible improvement may be more closely related to patient outcomes.

OBJECTIVES

To develop a hospital-level summary process measure adherence score that reflects how hospitals organize cardiac care and the range for possible improvement; and to compare associations of hospital adherence to this score and adherence to a composite score based on the Centers for Medicare and Medicaid Services scoring system with inpatient mortality.

RESEARCH DESIGN AND SUBJECTS

Hospital-level analysis of 7 process measures for acute myocardial infarction (AMI) and 4 process measures for heart failure at 4226 hospitals, and inpatient mortality after AMI at 1351 hospitals in the United States. Data are from the Hospital Compare and Joint Commission Core Measures databases for October 2004 through September 2006.

MEASURES

Associations between composite scores based on Centers for Medicare and Medicaid Services methodology and alternative adherence scores with inpatient survival after AMI.

RESULTS

In principal components analysis, hospital cardiac care varied between hospitals largely along the lines of "clinical" (ie, pharmacologic interventions) and "administrative" (ie, patient instructions or counseling) activities. A scoring system reflecting this organization was strongly associated with inpatient survival and fit the mortality data better than the composite score. Higher administrative activities scores, holding the clinical activities score fixed, were associated with lower survival.

CONCLUSIONS

In-hospital cardiac care is organized by clinical and administrative processes of care. Pay-for-performance schemes that incentivize hospitals to focus on administrative process measures may be associated with decreased adherence to clinical processes. A pay-for-performance scheme that acknowledges these factors may be associated with improved inpatient mortality.

[Acute coronary syndrome: unstable angina and myocardial infarction]

The acute coronary syndrome comprises unstable angina, non-ST-segment elevation myocardial infarction, and ST-segment elevation myocardial infarction. A successful and stable revascularisation of the infarct related vessel, and the prevention of the loss of myocardium are the main therapeutic targets, as cardiovascular mortality and long term quality of life are essentially determined by left ventricular function. The clinical diagnosis comprises clinical symptoms, ECG-changes, and cardiac troponins. Early percutaneous coronary intervention (PCI) has become the most common method of coronary revascularisation. If PCI is not available, systemic thrombolysis is an alternative after exclusion of contraindications. Parenteral anticoagulation with intravenous or subcutaneous heparines, antithrombotic therapy and HMG-CoA reductase inhibitors are the common secondary drug therapy. Moreover, to prevent left ventricular remodelling ACE-inhibitors, angiotension 2-receptor antagonists, and beta-blocker are indicated.

Potential diversion rates associated with prehospital acute myocardial infarction triage strategies

Thisstudy examines the potential number of patients who would be diverted from hospitals without percutaneous coronary intervention (PCI) capability, to centers with this capability, as a result of prehospital triage strategies for patients with suspected acute myocardial infarction (AMI). All patients with AMI admitted during a 1-year study period at two urban hospitals without PCI capability were identified through a prospectively maintained AMI registry. Pertinent clinical data were extracted from the AMI registry and patients' medical records. Patients were considered to have been eligible for prehospital diversion to a PCI center if they had ischemic symptoms of greater than 20 min and less than 24 h duration, and electrocardiographic changes consistent with ST elevation AMI (STEMI) were noted at the time of Emergency Department (ED) arrival or before arrival. There were 176 patients with AMI identified. One hundred three patients were transported to the ED by Emergency Medical Services (EMS). Of these, 39 had a clinical presentation and diagnostic EKG evidence of STEMI on ED arrival. Implementation of a prehospital triage strategy for patients with suspected STEMI may result in the diversion of 22% of patients with AMI from hospitals without PCI capability, assuming perfect specificity of prehospital triage. Actual implementation of a prehospital AMI diversion protocol may have an even greater impact on nonreceiving hospitals.

Early and late clinical outcomes after primary stenting of the unprotected left main coronary artery stenosis in the setting of acute myocardial infarction

BACKGROUND

Acute left main coronary artery occlusion is a dramatic condition with very high mortality. The study was aimed to evaluate the effect of primary stenting in patients with left main coronary artery (LMCA) disease in the setting of acute myocardial infarction (AMI).

METHODS

Between June 1997 and April 2002, primary stenting for left main coronary artery disease was performed in 18 patients with acute myocardial infarction. We evaluated early and late clinical outcomes, and prognostic determinants in this clinical setting.

RESULTS

Mean ages of patients were 59 +/- 12 years. Fourteen patients had cardiogenic shock on admission. Angiographic success (TIMI flow > or = 2 and diameter stenosis < 30% after stenting) was achieved in 17 patients (94%). In-hospital death occurred in eight patients (44%). Two patients (11%) received emergent bypass surgery because of hemodynamic instability after primary stenting. On univariate analysis, good pre-intervention TIMI flow (grade > or = 2) was identified as a good prognostic determinant of in-hospital survival. During mean follow-up of 39 +/- 22 months, there was no late death and one patient received bypass surgery. Probability of freedom from death at 3-year was 56 +/- 12%.

CONCLUSION

Primary stenting is a valuable therapeutic strategy for left main coronary disease in the setting of acute myocardial infarction, and it might save the life especially in patients with good pre-intervention TIMI flow (grade > or = 2). Long-term clinical outcome of patients surviving to hospital discharge is favorable.

Guidelines for indications for coronary revascularization in The Netherlands

In 1996 the Minister of Public Health, Welfare and Sports in The Netherlands published a 'Planning Decree Special Interventions in the Heart'. She requested from the professional organizations guidelines for the indications for interventions in the heart. A working group was formed with representatives from the Dutch professional organizations for cardiology and thoracic surgery, to address this issue for patients with coronary artery disease. The working group confirmed the need to discuss all patients who are considered for either elective or emergency revascularization during a multidisciplinary consultation in (or with) one of the specialized Dutch hospitals. During this meeting of the 'heart team', at least one interventional cardiologist and one thoracic surgeon should be present. There are three possible outcomes of the heart team's consultations for each patient: drug therapy only ('conservative management'), coronary surgery or catheter intervention. For each case, the team should indicate the expected benefit, the risk of the intervention, the urgency and the estimated waiting time. The guidelines presented in this paper address these issues for three patient categories: stable angina pectoris, unstable angina pectoris and acute myocardial infarction.

[Coronary artery surgery in the first 24 hours after myocardial infarction]

BACKGROUND

Thrombolysis and angioplasty in the first hours after myocardial infarction minimize necrosis, leading to better early and late survival, but these therapies have limited effect in patients with three-vessel disease and cardiogenic shock. Emergency coronary surgery is an alternative treatment in some cases.

AIM

To assess perioperative complications, mortality and long-term survival in patients undergoing coronary surgery within 24 h of myocardial infarction.

PATIENTS AND METHODS

We retrospectively studied 57 patients undergoing surgery within 24 h of the onset of symptoms of myocardial infarction between 1982 and 1998. Multiple vessel disease was present in 31 patients (54%), shock or cardiac arrest in 19 (33%) and coronary angiography complications in 7 (12%). The mean time between onset of symptoms and surgery was 6.32 h. At the beginning of surgery 32 patients (56%) were hemodynamically stable, 15 (26%) were in shock and 10 (17%) were in cardiac arrest.

RESULTS

The operative mortality was 0% for those who were hemodynamically stable at the start of surgery and 44% (11 of 25 patients) for those in shock or cardiac arrest. Shock or prior cardiac arrest were associated with higher rates of sternal infection and heart failure and longer hospital stays.Follow-up (mean 67 months) was possible for all remaining patients. The 5- and 10-year survival rates were 89 and 82%, respectively, for patients who were hemodynamically stable at the time of surgery. Five-year survival was 55%, however, for those who underwent surgery in shock or cardiac arrest. The overall rate of freedom from myocardial infarction, angioplasty or reoperation was over 95% at 5 years and over 85% at 10 years of follow-up. Age and shock or cardiac arrest were risk factors for a poor long-term outcome.

CONCLUSION

The early and long-term outcome of coronary surgery within 24 h of myocardial infarction is good for patients who are hemodynamically stable when surgery begins. Shock and cardiac arrest are important risk factors for complication and death. Coronary artery bypass grafting is a good treatment option in the first hours after myocardial infarction.

Determinants of coronary blood flow following primary angioplasty for acute myocardial infarction

The aim of this study was to evaluate determinants of coronary blood flow following primary angioplasty (PA) in acute myocardial infarction (AMI). The corrected TIMI (thrombolysis in myocardial infarction) frame count and the TIMI flow grade were used as indexes of coronary blood flow, and its determinants were examined in 115 consecutive AMI patients who underwent PA (pain onset </= 12 hr). The following were validated as univariate predictors of slower corrected TIMI frame count: a lower pressure-derived farctional collateral flow (PDCF) index (P < 0.01), poor angiographic collaterals (P < 0.01), TIMI flow 0, 1 before PA (P < 0.05), and the presence of heavy thrombi (P < 0.01). The PDCF index and the presence of heavy thrombi were independent predictors of the corrected TIMI frame count. Likewise, the PDCF index (chi(2) = 12.9; P < 0.01) and the presence of heavy thombi (chi(2) = 11.4; P < 0.01) were independent predictors of TIMI 3 flow. In conclusion, collateral flow and the presence of thrombi are major determinants of coronary blood flow after PA in AMI.

Recombinant human, active site-blocked factor VIIa reduces infarct size and no-reflow phenomenon in rabbits

Oxygen free radicals induce de novo synthesis of tissue factor (TF), the initiator of the extrinsic pathway of coagulation, within the coronary vasculature during postischemic reperfusion. In the present study we wanted to assess whether TF expression might cause myocardial injury during postischemic reperfusion. Anesthetized rabbits underwent 30 min of coronary occlusion followed by 5.5 h of reperfusion. At reperfusion the animals received 1) saline (n = 8), 2) human recombinant, active site-blocked activated factor VII (FVIIai, 1 mg/kg, n = 8), or 3) human recombinant activated FVII (FVIIa, 1 mg/kg, n = 8). FVIIai binds to TF as native FVII, but with the active site blocked it inhibits TF procoagulant activity. The area at risk of infarction (AR), the infarct size (IS), and the no-reflow area (NR) were determined at the end of the experiment. FVIIai resulted in a significant reduction in IS and NR with respect to control animals (28.1 +/- 11.3 and 11.1 +/- 6.1% of AR vs. 59.8 +/- 12.8 and 24.4 +/- 2.7% of AR, respectively, P < 0.01), whereas FVIIa resulted in a significant increase in IS and NR to 80.1 +/- 13. 1 and 61.9 +/- 13.8% of AR, respectively (P < 0.01). In conclusion, TF-mediated activation of the extrinsic coagulation pathway makes an important contribution to myocardial injury during postischemic reperfusion.

Cost-effectiveness of reperfusion strategies

Reperfusion of acute myocardial infarction has become the standard of management during the first few hours. Cost per year of life saved is one measure of the effectiveness of reperfusion strategies. Estimates of the cost per year of life saved have been approximately $17,000 for streptokinase and percutaneous transluminal coronary angioplasty and approximately $33,000 for tissue plasminogen activator. Assuming that percutaneous transluminal coronary angioplasty is more effective than thrombolysis, we calculated the cost-effectiveness of this strategy in different hospital settings. The estimated costs in hospitals with existing cardiac catheterization laboratories were $11,000 per year of life saved for primary angioplasty and $14,000 for thrombolysis compared with no intervention. In hospitals without catheterization facilities, it would be cost-ineffective to build such laboratories only to treat acute infarction with angioplasty. Preliminary results suggest that stenting may also be cost-effective in association with angioplasty.

Tissue-type plasminogen activator therapy versus primary coronary angioplasty: impact on myocardial tissue perfusion and regional function 1 month after uncomplicated myocardial infarction

OBJECTIVES

This study sought to compare the impact of primary coronary angioplasty and thrombolytic therapy for acute myocardial infarction (AMI) on 1-month infarct size and microvascular perfusion.

BACKGROUND

The effect of the reperfusion strategies of primary coronary angioplasty and thrombolytic therapy on microvascular integrity still remains to be determined.

METHODS

Sixty-two consecutive patients with a first AMI, undergoing intravenous tissue-type plasminogen activator (t-PA) therapy (32 patients, Group I) or primary angioplasty (30 patients, Group II), were studied. Only patients with 1-month Thrombolysis in Myocardial Infarction (TIMI) flow grade 2 or 3 were selected for the study. Patients in whom primary angioplasty was unsuccessful or those with clinical evidence of failed reperfusion were excluded. Microvascular perfusion was assessed at 1 month by intracoronary injection of sonicated microbubbles. Contrast score index (CSI) and wall motion score index (WMSI) were derived using qualitative methods.

RESULTS

At baseline there were no significant differences between groups for age, risk factors, time to hospital presentation, Killip class on admission, prevalence of multivessel disease or anterior infarct site, infarct area extension before reperfusion, peak creatine kinase levels and postinfarction treatment. Conversely, significant differences between groups were found at follow-up for percent residual infarct related-artery (IRA) stenosis (70 +/- 12 vs 36 +/- 14 [mean +/- SD], p = 0.0001), CSI (1.02 +/- 0.4 vs. 1.49 +/- 0.5, p = 0.0003) and WMSI (1.67 +/- 0.3 vs. 1.45 +/- 0.3, p = 0.015). In particular, in the subset of patients with TIMI grade 3 flow, a perfusion defect occurred in one or more segments subtended by the IRA in 72% of Group I versus 31% of Group II patients (p < 0.00001) and in 27% of Group I versus 8% of Group II segments (p < 0.00001).

CONCLUSIONS

The present study shows, in a highly selected cohort with successful IRA recanalization, that primary angioplasty is more effective than thrombolysis in preserving microvascular flow and preventing extension of myocardial damage at 1-month after AMI.

Projected cost-effectiveness of primary angioplasty for acute myocardial infarction

OBJECTIVES

This study sought to evaluate the cost-effectiveness of primary angioplasty for acute myocardial infarction under varying assumptions about effectiveness, existing facilities and staffing and volume of services.

BACKGROUND

Primary angioplasty for acute myocardial infarction has reduced mortality in some studies, but its actual effectiveness may vary, and most U.S. hospitals do not have cardiac catheterization laboratories. Projections of cost-effectiveness in various settings are needed for decisions about adoption.

METHODS

We created a decision analytic model to compare three policies: primary angioplasty, intravenous thrombolysis and no intervention. Probabilities of health outcomes were taken from randomized trials (base case efficacy assumptions) and community-based studies (effectiveness assumptions). The base case analysis assumed that a hospital with an existing laboratory with night/weekend staffing coverage admitted 200 patients with a myocardial infarction annually. In alternative scenarios, a new laboratory was built, and its capacity for elective procedures was either 1) needed or 2) redundant with existing laboratories.

RESULTS

Under base case efficacy assumptions, primary angioplasty resulted in cost savings compared with thrombolysis and had a cost of $12,000/quality-adjusted life-year (QALY) saved compared with no intervention. In sensitivity analyses, when there was an existing cardiac catheterization laboratory at a hospital with > or = 200 patients with a myocardial infarction annually, primary angioplasty had a cost of < $30,000/QALY saved under a wide range of assumptions. However, the cost/QALY saved increased sharply under effectiveness assumptions when the hospital had < 150 patients with a myocardial infarction annually or when a redundant laboratory was built.

CONCLUSIONS

At hospitals with an existing cardiac catheterization laboratory, primary angioplasty for acute myocardial infarction would be cost-effective relative to other medical interventions under a wide range of assumptions. The procedure's relative cost-ineffectiveness at low volumes or redundant laboratories supports regionalization of cardiac services in urban areas. However, approaches to overcoming competitive barriers and close monitoring of outcomes and costs will be needed.

Thrombolytic therapy versus primary angioplasty. Which offers the best outcome after myocardial infarction?

The best technique for reestablishing blood flow after myocardial infarction has been the subject of heated debate for more than a decade. An the answer is still elusive. Which option is the safest? Which salvages the most heart tissue? Dr Faxon explains the pros and cons of both thrombolysis and angioplasty and discusses the "90 rule," which helps determine the optimal reperfusion strategy for each individual patient.

Randomized comparison of primary coronary angioplasty with thrombolytic therapy in low risk patients with acute myocardial infarction

OBJECTIVES

We sought to compare primary coronary angioplasty and thrombolysis as treatment for low risk patients with an acute myocardial infarction.

BACKGROUND

Primary coronary angioplasty is the most effective reperfusion therapy for patients with acute myocardial infarction; however, intravenous thrombolysis is easier to apply, more widely available and possibly more appropriate in low risk patients.

METHODS

We stratified 240 patients with acute myocardial infarction at admission according to risk. Low risk patients (n = 95) were randomized to primary angioplasty or thrombolytic therapy. The primary end point was death, nonfatal stroke or reinfarction during 6 months of follow-up. Left ventricular ejection fraction and medical charges were secondary end points. High risk patients (n = 145) were treated with primary angioplasty.

RESULTS

In low risk patients, the incidence of the primary clinical end point (4% vs. 20%, p < 0.02) was lower in the group with primary coronary angioplasty than in the group with thrombolysis, because of a higher rate of reinfarction in the latter group. Mortality and stroke rates were low in both treatment groups. There were no differences in left ventricular ejection fraction or total medical charges. High risk patients had a 14% incidence rate of the primary clinical end point.

CONCLUSIONS

Simple clinical data can be used to risk-stratify patients during the initial admission for myocardial infarction. Even in low risk patients, primary coronary angioplasty results in a better clinical outcome at 6 months than does thrombolysis and does not increase total medical charges.