From October 2005 to December 2006, 621 patients with AMI (439 ST-segment elevation MI and 182 non-ST-segment elevation MI) were registered and followed prospectively at Chonnam National University Hospital, Gwangju, Korea, and the analysis was performed retrospectively. Inclusion criteria were the presence of a non-ST-segment elevation MI or an ST-segment elevation MI. The presence of ST-segment elevation MI was determined by >30 min of continuous chest pain, a new ST-segment elevation ≥2 mm on at least two contiguous electrocardiographic leads, and creatine kinase-MB >3 times normal. The presence of non-ST-segment elevation MI was diagnosed by chest pain and a positive cardiac biochemical marker without new ST-segment elevation. We excluded patients with prior MI, subacute or late stent thrombosis, restenosis after stenting, coronary artery bypass graft failure, hepatic or renal dysfunction (alanine aminotransferase and aspartate aminotransferase >2 times normal, creatinine >1.5 mg/dl), or current use of any lipid-lowering drugs. Early initiation of statin treatment was defined as prescription of statins during hospitalization (statin group: 545 patients), and the control group was not prescribed statins during hospitalization or at discharge (nonstatin group: 76 patients). The hospital records of all patients were reviewed to obtain information on clinical demographics and medical history. Risk factors were reviewed via retrospective chart review.

All laboratory values were measured after the patients had fasted overnight. The serum levels of total cholesterol, LDL-cholesterol, high-density lipoprotein (HDL)-cholesterol, and triglyceride were measured by standard enzymatic methods. High-sensitivity C-reactive protein (hs-CRP) was analyzed turbidimetrically with sheep antibodies against human CRP; this has been validated against the Dade-Behring method.13

Infarct-related arteries were identified by using a combination of electrocardiographic findings, left ventricular wall motion abnormalities on left ventricular angiogram or echocardiogram, and coronary angiographic findings. Coronary angiogram was performed in 588 patients. Of these patients, 544 patients were treated with stent implantation (442 patients with drug-eluting stents and 102 patients with bare metal stents), and balloon angioplasty was done in 44 patients. Stent implantation was performed as previously described.14 Patients were treated with aspirin [300 mg loading before percutaneous coronary intervention (PCI) and 100~200 mg daily, indefinitely] and clopidogrel (300 or 600 mg before PCI and 75 mg daily continued for at least 6 months). Glycoprotein IIb/IIIa inhibitors were used at the operator's decision.

The primary end point was occurrence of cardiac death during the 6-month follow-up. The secondary end point was the occurrence of the composite of cardiac death, MI, and target vessel revascularization during the 6-month follow-up. All deaths were considered to be of cardiac origin unless a noncardiac origin was established clinically or at autopsy. MI was defined by the presence of recurrent ischemic symptoms or electrocardiographic changes accompanied by a creatine kinase level that was more than twice the upper limit of the normal range or >50% higher than the value during the index hospitalization (with an elevated MB isoform level). Target vessel revascularization included bypass surgery or repeat PCI of the target vessels.

The Statistical Package for the Social Sciences (SPSS) for Windows, version 15.0 (Chicago, Illinois) was used for all analyses. Continuous variables were presented as the mean±SD; comparisons were conducted by Student's t-test or the nonparametric Wilcoxon test if the normality assumption was violated. Discrete variables were presented as percentages and relative frequencies; comparisons were conducted by chi-square statistics or Fisher's exact test as appropriate. Logistic regression analysis was used to identify the independent predictors of 6-month cardiac mortality. A p value <0.05 was considered statistically significant.

There were no significant differences in patient demographics or medications except for statin between the groups. The levels of LDL-cholesterol and hs-CRP were almost the same between the two groups (Table 1).

There were no significant differences in baseline coronary angiographic findings and procedural results between the two groups (Table 2). A total of 76% in the statin group and 78% in the nonstatin group had complex lesions, and 51% in the statin group and 53% in the nonstatin group had multivessel disease. Stents were used in 93% of the patients. Bare-metal stents were used in 18% and drug-eluting stents were used in 82% of the patients. The occurrence of post-PCI no-reflow phenomenon [which was defined as post-PCI thrombolysis in myocardial infarction (TIMI) flow grade 0, 1, and 2] was not significantly different between the groups.

Follow-up data were available for all patients. During the 6-month follow-up, 22 patients died (4%), including 7 patients from the control group (9%) and 15 patients from the statin group (3%) (p=0.004). Six-month major adverse cardiac events (including cardiac death, MI, and target vessel revascularization) occurred less frequently in patients who had taken early statin therapy than in patients who had not taken statin therapy (Fig. 1).

The patients who experienced cardiac death were older and had a higher Killip class on admission than did the patients without cardiac death. The patients who experienced cardiac death had more atrial fibrillation and ventricular tachyarrhythmia and had more deteriorated left ventricular function on admission than did the patients without cardiac death. Serum creatinine was significantly higher, creatinine clearance was significantly lower, and the HDL-cholesterol level was significantly lower in the patients who experienced cardiac death than in the patients without cardiac death. Baseline hs-CRP was significantly higher in the patients who experienced cardiac death than in the patients without cardiac death (Table 3). There were no significant differences in types or daily dosages of statins used between the patients who experienced cardiac death and those who did not.

There were no significant differences in the infarct-related artery, ACC/AHA lesion type, or baseline or post-PCI TIMI flow grade between the groups. However, multivessel disease was more frequently observed in the patients who experienced cardiac death than in those who did not (Table 4).

Multiple logistic regression analysis was performed to determine independent predictors of 6-month cardiac mortality. The following variables were tested (all with p<0.2 in the univariate analysis): early initiation of statins, age, hypertension, smoking, Killip class III/IV, atrial fibrillation, ventricular tachyarrhythmia, ejection fraction, creatinine clearance, total cholesterol, HDL-cholesterol, hs-CRP, multivessel disease, baseline TIMI flow grade, and stent use. Early initiation of statin therapy and baseline hs-CRP level were the independent predictors of 6-month mortality [odds ratio (OR)=0.078, 95% CI: 0.008-0.808, p=0.032, and OR=1.314, 95% CI: 1.149-1.501, p<0.001, respectively).