Mortality Risk Higher for In-Hospital Myocardial Infarction

Laurie Barclay, MD

November 17, 2014

Patients developing inpatient-onset ST-elevation myocardial infarction (STEMI) had more than threefold greater in-hospital mortality than those patients with outpatient-onset STEMI, according to an analysis published in the November 19 issue of JAMA.

"Early reperfusion with percutaneous coronary intervention (PCI) or thrombolytic therapy remains the primary goal in the initial treatment of eligible patients presenting to a hospital with [STEMI]," write Prashant Kaul, MD, from the University of North Carolina, Chapel Hill, and colleagues. "Over the last decade, recognition that this strategy is of critical importance has prompted the development of a number of regional and national initiatives to facilitate and improve systems of care for STEMI.... These initiatives have focused exclusively on patients who develop STEMI outside of a hospital setting (outpatient-onset STEMI), and little is known about the incidence and outcomes of STEMI in patients hospitalized for non-acute coronary syndrome (ACS) conditions (inpatient­onset STEMI)."

The study goal was to evaluate the incidence and factors associated with treatment and outcomes of patients who developed inpatient­onset STEMI while hospitalized for conditions other than ACS. Using the California State Inpatient Database, the investigators identified 62,021 STEMIs that occurred in 303 hospitals between 2008 and 2011.

Of those, 3068 (4.9%) occurred in patients hospitalized for non-ACS conditions. Compared with patients with outpatient-onset STEMI, those with inpatient-onset STEMI were older (P < .001) and more likely to be women. Regression models were adjusted for age, sex, comorbid conditions, and hospital characteristics.

When the researchers examined possible associations among location of onset of STEMI, resource use, and outcomes, inpatient-onset was associated with worse outcomes than outpatient-onset STEMI. In-hospital mortality risk was more than threefold higher (33.6% vs 9.2%; P < .001), and patients were significantly less likely to be discharged home (33.7% vs 69.4%; P < .001).

In addition, fewer patients with inpatient-onset STEMI underwent cardiac catheterization compared with outpatient-onset (33.8% vs 77.8%; P < .001) or PCI (21.6% vs 65%; P < .001). Inpatient-onset STEMI was also linked to longer average length of stay (13.4 vs 4.7 days; P < .001) and greater inpatient costs ($245,000 vs $129,000; P < .001).

The authors note several study limitations including its retrospective design, possible residual confounding, and lack of data on admission diagnoses, elective vs urgent admission, and postdischarge mortality.

"The question of how to improve outcomes and define optimum treatment in hospitalized patients who experience a STEMI is an area that merits more attention and concern," the study authors write. "Although there have been improvements in treatment times and clinical outcomes in outpatients who have onset of STEMI, few initiatives have focused on optimizing care of hospitalized patients with onset of STEMI after admission."

This research was supported by the National Heart, Lung, and Blood Institute and the National Institute of General Medical Sciences. The authors have disclosed no relevant financial relationships.

JAMA. 2014;312:1999-2007. Full text

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