What are appropriate rates of invasive procedures following acute myocardial infarction? A systematic review

Routine invasive management after fibrinolysis in patients with ST-elevation myocardial infarction: a systematic review of randomized clinical trials

Background

Patients with ST-elevation myocardial infarction (STEMI) treated with fibrinolysis are increasingly, and ever earlier, referred for routine coronary angiography and where feasible, undergo percutaneous coronary intervention (PCI). We sought to examine the randomized clinical trials (RCTs) on which this approach is based.

Methods

We systematically searched EMBASE, Medline, and references of relevant studies. All contemporary RCTs (published since 1995) that compared systematic invasive management of STEMI patients after fibrinolysis with standard care were included. Relevant study design and clinical outcome data were extracted.

Results

Nine RCTs that randomized a total of 3320 patients were identified. All suggested a benefit from routine early invasive management. They were individually reviewed but important design variations precluded a formal quantitative meta-analysis. Importantly, several trials did not compare a routine practice of invasive management after fibrinolysis with a more selective 'ischemia-guided' approach but rather compared an early versus later routine invasive strategy. In the other studies, recourse to subsequent invasive management in the usual care group varied widely. Comparison of the effectiveness of a routine invasive approach to usual care was also limited by asymmetric use of a second anti-platelet agent, differing enzyme definitions of reinfarction occurring spontaneously versus as a complication of PCI, a preponderance of the 'soft' outcome of recurrent ischemia in the combined primary endpoint, and an interpretative bias when invasive procedures on follow-up were tallied as an endpoint without considering initial invasive procedures performed in the routine invasive arm.

Conclusions

Due to important methodological limitations, definitive RCT evidence in favor of routine invasive management following fibrinolysis in patients with STEMI is presently lacking.

Acute ischemic heart disease and interventional cardiology: a time for pause

BACKGROUND

A major change has occurred in the last few years in the therapeutic approach to patients presenting with all forms of acute coronary syndromes. Whether or not these patients present initially to tertiary cardiac care centers, they are now routinely referred for early coronary angiography and increasingly undergo percutaneous revascularization. This practice is driven primarily by the angiographic image and technical feasibility. Concomitantly, there has been a decline in expectant or ischemia-guided medical management based on specific clinical presentation, response to initial treatment, and results of noninvasive stratification. This 'tertiarization' of acute coronary care has been fueled by the increasing sophistication of the cardiac armamentarium, the peer-reviewed publication of clinical studies purporting to show the superiority of invasive cardiac interventions, and predominantly supporting (non-peer-reviewed) editorials, newsletters, and opinion pieces.

DISCUSSION

This review presents another perspective, based on a critical reexamination of the evidence. The topics addressed are: reperfusion treatment of ST-elevation myocardial infarction; the indications for invasive intervention following thrombolysis; the role of invasive management in non-ST-elevation myocardial infarction and unstable angina; and cost-effectiveness and real world considerations. A few cases encountered in recent practice in community and tertiary hospitals are presented for illustrative purposes The numerous and far-reaching scientific, economic, and philosophical implications that are a consequence of this marked change in clinical practice as well as healthcare, decisional and conflict of interest issues are explored.

SUMMARY

The weight of evidence does not support the contemporary unfocused broad use of invasive interventional procedures across the spectrum of acute coronary clinical presentations. Excessive and unselective recourse to these procedures has deleterious implications for the organization of cardiac health care and undesirable economic, scientific and intellectual consequences. It is suggested that there is need for a new equilibrium based on more refined clinical risk stratification in the treatment of patients who present with acute coronary syndromes.

Low utilization and wide interhospital variation in investigation of patients after acute myocardial infarction: inadequate resources or insufficient evidence?

BACKGROUND

Guidelines for the management of patients with acute myocardial infarction are available, but implementation may be difficult when resources are limited.

OBJECTIVE

The aim of this study was to investigate whether resources, manpower or access to specialist facilities affect care following myocardial infarction.

PATIENTS AND METHODS

A representative sample of 1595 patients in all 19 district general hospitals in Wales was analysed for differences in use of investigations and prescription of secondary prevention and how these factors were related to provision of cardiologists and coronary care beds and distance from specialist cardiac services.

RESULTS

Inpatient investigation rates were low and there were wide interhospital variations for exercise testing [mean 42%; interquartile range (IQR) 27-59%] and echocardiography (mean 46%; IQR 33-66%). In comparison, prescription of secondary prevention was similar to European standards and showed less interhospital variation (beta blockers mean 48%; IQR 44-54%; angiotensin-converting enzyme inhibitors mean 59%; IQR 43-63%). There was little association between investigation or secondary prevention rates and cardiac services, but overall rates and provision were low.

CONCLUSION

Delivery of care after acute myocardial infarction for stratifying risk and preventing recurrence was unrelated to relative provision or distance from specialist centres. Low use of investigations and high interhospital variability could imply limited access to resources such as echocardiography. Higher rates of prescription of drugs, with less variation between hospitals, argues against low utilization because of insufficient evidence.

Population need for coronary revascularisation: are national targets for England credible?

OBJECTIVE

To estimate the need for coronary revascularisation, by using an incidence of indications approach, among 45-84 year olds with stable angina, unstable angina, and acute myocardial infarction.

DESIGN

Modelling exercise. Six key steps along the pathway of care from initial diagnosis in primary or secondary care to revascularisation were defined and the frequency of indications estimated using routine data from hospital admissions and data from studies in the general population, and primary and secondary care.

SETTING AND PATIENTS

Mid-1998 population of England.

INTERVENTION

Coronary revascularisation.

MAIN OUTCOME MEASURE

Ability to benefit (need), defined by randomised trials, expert panel ratings from the ACRE (appropriateness of coronary revascularisation) study, or by informal consensus.

RESULTS

The need for coronary revascularisation was estimated to be 92 000 procedures, equivalent to a rate of 1861 per million population. Overall, the model of need exceeded current provision by 3.3:1, although among people aged 75 years and over the ratio was 7.7:1. A plausible upper estimate of need--obtained by assuming that 90% of patients with stable angina were referred from primary care and that angiography would be performed in 65% of patients with acute myocardial infarction and 75% of patients with unstable angina--was 2626 per million population.

CONCLUSIONS

The national target of 1500 revascularisation procedures per million population is credibly related to population need, although upper estimates of need are considerably higher. Better understanding is required of the benefits of referring patients with specific indications from primary care. The greatest relative increase in provision is required for those aged 75 and older, among whom trial evidence of benefit is scant.