Optimal medical therapy for non-ST-segment-elevation acute coronary syndromes: exploring why physicians do not prescribe evidence-based treatment and why patients discontinue medications after discharge.

Background: Acute coronary syndrome (ACS) patients in the highest risk categories are least likely to receive evidence-based treatments (EBTs). We sought to determine why physicians do not prescribe EBTs for patients with non-ST-segment-elevation ACSs and the factors determining use of these treatments after 1 year.

Methods And Results: One thousand nine hundred fifty-six non-ST-segment-elevation ACS patients were enrolled in the prospective, multicenter Canadian ACS registry II between October 2002 and December 2003. Each patient's physician gave reasons why guideline-indicated medication(s) was not prescribed during hospitalization. Medication use and reason(s) for discontinuation after 1 year were obtained by telephone interview of the patients. The commonest reason for not prescribing EBTs was "not high-enough risk" or "no evidence/guidelines to support use." However, Global Registry of Acute Coronary Events scores of patients not treated for this reason were often similar to or higher than those of patients prescribed such treatment. After 1 year, 77% of patients not on optimal ACS treatment at discharge remained without optimal treatment, and overall antiplatelet, β-blocker, and angiotensin-converting enzyme inhibitor use declined. Approximately one third of patients not taking EBTs had stopped their medication without instruction from their doctor.

Conclusions: Nonprovision of EBTs may be due to subjective underestimation of patient risk and hence, likely treatment benefit. Oversights in care delivery were also apparent. Objective risk stratification, combined with efforts to ensure provision and adherence to EBTs, should be encouraged.