For decades, we’ve been giving an aspirin to every patient suspected of having acute coronary syndrome (ACS) who enters the emergency department. The ISIS-2 trial published in The Lancet in August 1988 (“Randomised trial of intravenous streptokinase, oral aspirin, both, or neither among 17,187 cases of suspected acute myocardial Infarction”) concluded that, of patients ultimately having an ST elevation myocardial infarction 9STEMI), the number needed to treat (NNT) to prevent one death at 30 days was 42. The death rate went from 11.8 percent to 9.4 percent.
However, there are a couple things to consider about ISIS-2: First, chest pain patients with a STEMI represent a very small fraction of the suspected ACS patients presenting to the emergency department. Second, the death rate from STEMI is now about 5 percent, much lower than in 1988. Despite these two factors that would substantially mitigate the efficacy of aspirin in chest pain patients, we still give it to everyone who has chest pain suspected to be ACS.
Nobody argues with giving aspirin even when the vast majority who get it will likely receive no benefit. One aspirin may help a very small percentage of suspected ACS patients and isn’t going to hurt anyone—a no-brainer.