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

Objective: To assess the evidence that higher rates of coronary angiography (CA) and revascularisation (RV) in the subacute phase of acute myocardial infarction (AMI) improve patient outcomes. Data sources: MEDLINE 1990 - December 1999, Current Contents 1990-1999, Coc hrane Library (Issue 4, 1999), HealthSTAR 1990-1999, selected websites and bibliographies of retrieved articles. Study selection and data extraction: Studies selected were (I) randomised t rials comparing outcomes of "invasive" versus "conservative" use of CA and RV following AMI; (2) observational studies with formal methods comparing o utcomes of high versus low rates of use of these procedures; and (3) clinic al practice guidelines (CPGs), expert panel statements and decision analyse s which met critical appraisal criteria, and which specified procedural ind ications. Outcome measures were rates of mortality, re-infarction and limit ing or unstable angina. Data synthesis: 56 articles were identified; 24 met inclusion criteria. Poo led data from nine RCTs of "invasive" (CA rate 96%; RV rate 66%) versus "co nservative" (CA rate 28%; RV rate 19%) strategies showed no significant dif ferences in mortality or re-infarction rates. Pooled results from 12 observ ational studies showed no mortality differences, but an excess re-infarctio n rate (8.0% vs 6.4%; P<0.001) in high- versus low-rate populations. Eviden ce of survival benefit from procedural intervention was strongest for patie nts with recurrent ischaemia combined with left Ventricular dysfunction. Conclusions: In the subacute phase of AMI, rates of CA and RV in excess of 30% and 20%, respectively, may not confer additional benefit in preventing death or re-infarction. However, variability between studies in design, pat ient selection, and extent of cross-over from medical to procedural groups, as well as limited data on symptom status, limits generalisability of resu lts.