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Background: Although ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction (AMI) have been the focus of intense clinical investigation, limited information exists on characteristics and hospital mortality of patients not enrolled in clinical trials. Previous large databases have reported declining mortality of patients with STEMI but have not noted substantial mortality change among those with NSTEMI., Methods: The National Registry of Myocardial Infarction enrolled 2,515,106 patients at 2,157 US hospitals from 1990 to 2006. Of these, we evaluated 1,950,561 with diagnoses reflecting acute myocardial ischemia on admission., Results: From 1990 to 2006, the proportion of NSTEMI increased from 14.2% to 59.1% (P < .0001), whereas the proportion of STEMI decreased. Mean age increased (from 64.1 to 66.4 years, P < .0001) as did the proportion of females (from 32.4% to 37.0%, P < .0001). Patients were less likely to report prior angina, prior AMI, or family history of coronary artery disease but more likely to report history of diabetes, hypertension, current smoking, heart failure, prior revascularization, stroke, and hyperlipidemia. From 1994 to 2006, hospital mortality fell among all patients (10.4% to 6.3%), STEMI (11.5% to 8.0%), and NSTEMI (7.1% to 5.2%), (all P < .0001). After adjustment for baseline covariates, hospital mortality fell among all patients by 23.6% (odds ratio [OR] 0.764, 95% CI 0.744-0.785), STEMI by 24.2% (OR 0.758, 0.732-0.784), and NSTEMI by 22.6% (OR 0.774, 0.741-0.809), all P < .001., Conclusions: This large, observational database from 1990 to 2006 shows increasing prevalence of NSTEMI and, despite higher risk profile on presentation, falling risk-adjusted hospital mortality in patients with either STEMI or NSTEMI.

A 42-year-old man presented with shortness of breath, weakness, and diaphoresis, and developed a new left bundle branch block while under evaluation in the Emergency Department. At emergency cardiac catheterization, he was found to have only insignificant coronary disease, and a hyperdynamic ventricle. Despite these findings, he subsequently developed profound bradycardia and hypotension, which were refractory to standard therapies including pressors, calcium, and transvenous pacing. He gradually improved over several days and made a full recovery, after which he admitted to taking multiple calcium channel blockers (CCBs) in an attempt to self-medicate for symptoms he related to his lifelong paroxysmal supraventricular tachycardia. This is the first report of a CCB overdose mimicking an acute myocardial infarction, and highlights the fact that CCB overdose must be considered in the differential diagnosis of some patients who present with apparent acute myocardial infarction.

The use of magnesium in patients with acute myocardial infarction (AMI) is debated, largely as a result of conflicting data from randomized controlled trials. This study evaluated the use and impact on mortality of intravenous magnesium in the treatment of patients with AMI in the United States based on data from the Second National Registry of Myocardial Infarction. Only 5.1% of 173,728 patients from 1,326 hospitals received intravenous magnesium within the first 24 hours after an AMI, and this was more common in the 59,798 patients who received thrombolytic therapy or who underwent primary percutaneous transluminal coronary angioplasty (PTCA) or coronary bypass grafting (CABG) than in the 113,930 patients who did not receive any reperfusion therapy (8.5% vs 3.4%, p <0.01). Magnesium use was associated with younger age, Q-wave AMI, congestive heart failure on admission, thrombolytic therapy, primary PTCA or CABG, ventricular tachycardia or ventricular fibrillation, and beta blocker or lidocaine use in the first 24 hours (all odds ratio > 1.2, p <0.001). Magnesium use was associated with increased mortality (odds ratio 1.25, 95% confidence interval 1.12 to 1.34) and with a higher mortality in patients without initial reperfusion therapy (20.2% vs 13.2%, p <0.0001) or who underwent primary PTCA or CABG (10.2% vs 7.3%, p = 0.002), but not in patients who received thrombolytic therapy (6.2% vs 5.9%, p = NS). Thus, magnesium is used infrequently in the treatment of AMI and may be associated with worse outcome.