Objectives: Elevated low-density lipoprotein cholesterol and triglycerides are major risk factors for coronary artery disease. However, fatty acids from triglycerides are a major energy source, low-density lipoprotein cholesterol is critical for cell membrane synthesis, and both are critical for cell survival. This study was designed to clarify the relationship between lipid profile, morbidity as assessed by Killip classification, and 30-day mortality in patients with acute myocardial infarction.
Design: A noninterventional observational study.
Setting: Coronary care unit in a university hospital.
Patients: Seven hundred twenty-four patients with acute myocardial infarction in the coronary care program of the Bureau of Health Promotion were analyzed.
Measurements and main results: Low-density lipoprotein cholesterol and triglyceride levels were significantly lower in high-Killip (III+IV) patients compared with low-Killip (I+II) patients and in those who died compared with those who survived beyond 30 days (both p<0.001). After adjustment for risk factors, low-density lipoprotein cholesterol less than 62.5 mg/dL and triglycerides less than 110 mg/dL were identified as optimal threshold values for predicting 30-day mortality and were associated with hazard ratios of 1.65 (95% CI, 1.18-2.30) and 5.05 (95% CI, 1.75-14.54), and the actual mortality rates were 23% in low low-density lipoprotein, 6% in high low-density lipoprotein, 14% in low triglycerides, and 3% in high triglycerides groups, respectively. To test the synergistic effect, high-Killip patients with triglycerides less than 62.5 mg/dL and low-density lipoprotein cholesterol less than 110 mg/dL had a 10.9-fold higher adjusted risk of mortality than low-Killip patients with triglycerides greater than or equal to 62.5 mg/dL and low-density lipoprotein cholesterol greater than or equal to 110 mg/dL (p<0.001). The lipid paradox also improved acute myocardial infarction short-term outcomes prediction on original Killip and thrombolytic in myocardial infarction scores.
Conclusions: Low low-density lipoprotein cholesterol, low triglycerides, and high Killip severity were associated with significantly higher 30-day in-hospital mortality in patients presenting with acute myocardial infarction. The initial lipid profile of patients with acute myocardial infarction may therefore hold prognostic value.