Treatment and outcomes of non-ST elevation acute coronary syndromes in relation to burden of pre-existing vascular disease

Background: Patients with atherosclerotic disease in one territory often have disease in other vascular territories. However, the relationships between pre-existing vascular disease and the treatment and outcome of acute coronary syndrome (ACS), have not been well characterized.

Methods: The Canadian ACS2, Global Registry of Acute Coronary Events (GRACE/GRACE(2)), and Canadian Registry of Acute Coronary Events (CANRACE) were used to obtain data on 10,667 non-ST segment elevation acute coronary syndrome (NSTEACS) patients between 2002 and 2008. Multivariable analysis was used to examine the relationships between the number of vascular beds affected and both in-hospital coronary angiography and in-hospital mortality. The ACS2 registry (2002-2003) included physician-reported reasons for non-invasive management, which were stratified by vascular disease burden.

Results: Patients with more vascular disease had higher GRACE risk scores at presentation, but less frequently received antiplatelet agents and angiography. The most common reason in the ACS2 registry for patients who did not undergo angiography was "not high enough risk." There was an independent inverse relationship between the extent of vascular disease and in-hospital angiography. Patients with higher vascular disease burden had higher unadjusted in-hospital mortality. In multivariable analysis, patients with 1 vascular territory affected had the lowest and those with 3 vascular beds affected had the highest adjusted in-hospital mortality. In the ACS2 registry, patients with more extensive vascular disease had higher rates of 1-year mortality and death/re-infarction (both p for trend <0.001).

Conclusions: NSTEACS patients with more vascular disease received less intensive treatment, with an associated worse outcome. This undertreatment might be partly mediated by physicians' underestimation of patient risk. More aggressive risk factor modification and intensive ACS therapies may improve the outcome of these high-risk patients.