AbstractFailure to routinely assess the state of knowledge as new studies accumulate results in 1) non-use of effective interventions, 2) continued use of ineffective or harmful interventions, and 3) unnecessary research. We use a published cumulative meta-analysis of interventions to reduce the harms of acute myocardial infarctions (1966-1992), and applied population attributable risk to assess the mortality consequences of the failure to cumulatively assess the state of knowledge. Failure to use knowledge that would have been available with cumulative meta-analysis may have resulted in annual estimated mortality: 41,000 deaths from non-use of intravenous dilators, 35,000 deaths from non-use of aspirin, and 37,000 deaths annually from non-use of ß-blockers. Continued use of Class 1 anti-arrhythmic drugs, which would have been found to be harmful in 1981, resulted 39,000 deaths annually. Failure to routinely update the state knowledge can have large health consequences. The process of building knowledge and practice in medicine and public health needs fundamental revision.