Prognosis of Troponin-Positive Patients with Non-Obstructive Coronary Artery Disease

INTRODUCTION Troponin elevation is an independent risk factor for mortality, but the prognosis of patients with troponin elevation and non-obstructive coronary artery disease (CAD) is unknown. Recent data have suggested an increased risk of mortality. This study was performed to further investigate the outcomes of troponin-positive patients with obstructive and non-obstructive CAD. METHODS A retrospective cohort analysis was performed of all patients with raised troponin presenting to Kettering General Hospital (January 2010 to December 2011, n = 1,351). The patients who had angiograms were stratified anatomically into obstructive CAD and non-obstructive CAD (≤50% stenosis). The obstructive CAD group (O-CAD) was sub-analyzed by management strategy: emergency re-vascularization (<12 h), urgent, delayed, and medically managed. Patients with non-obstructive CAD were grouped by the cause of the raised troponin if this could be identified (NO-CAD-I) or cause remained unidentified (NO-CAD-U). The major adverse cardiac and cerebrovascular event (MACCE) and mortality rates were calculated at 30 days and 1-year follow-up. RESULTS There was a preponderance of hypertension and severe renal impairment in the non-obstructive CAD group. The patients with NO-CAD-U were a low-risk group (MACCE at 1-year follow-up = 0). The remaining NO-CAD-I group had a similar risk to the O-CAD group for MACCE and mortality at 30 days and 1-year follow-up. In fact, at 1-year follow-up, the NO-CAD-I patients when compared with the subgroups of O-CAD, had higher MACCE rates and mortality compared with the emergency re-vascularized group [MACCE: relative risk (RR) (95% CI) = 2.27 (1.29-3.40), P = 0.0047; mortality: RR (95% CI) = 2.08 (1.10-3.93), P = 0.024]. This was driven by higher risk non-cardiac death [RR (95% CI) = 4.10 (1.53-10.99), P = 0.005]. CONCLUSION Patients with identified cause for raised troponin and non-obstructive CAD are at equivalent risk of MACCE and mortality at 30 days and 1-year follow-up compared to those with obstructive CAD.