NEW YORK (Reuters Health) – Outcomes in patients with acute MI undergoing percutaneous coronary intervention are better with increasing levels of LDL cholesterol, a Korean group reports. However, this apparent paradox is explained by older age and more comorbidities among patients with lower LDL cholesterol.

Dr. Myung Ho Jeong, with Chonnam National University Hospital, Gwangju, Korea, and colleagues analyzed data from a national registry covering 9571 patients who underwent PCI after an acute MI.

As described in the October 15th issue of the American Journal of Cardiology, “Patients were categorized into 5 groups according to baseline LDL cholesterol level:<70, 70 to 99, 100 to 129, 130 to 159, and >\=160 mg/dL.”

The researchers found that the success rate of PCI, in-hospital complications, and in-hospital mortality were all better as LDL cholesterol increased, up to levels at or above 160 mg/dL. For example, the rate of hospital deaths was 7.7% in the lowest LDL cholesterol quintile, then 2.7%, 2.1%, 1.8% and 2.4% in increasing quintiles.

Similarly, the composite major cardiac event and mortality rate at 1 and 12 months decreased as LDL cholesterol increased, except for patients with LDL cholesterol levels at or greater than 160 mg/dL.

“The 12-month mortality rate was significantly higher in patients with LDL cholesterol levels <70 mg/dL than in those with LDL cholesterol levels >70 mg/dL,” the team reports.

However, LDL cholesterol levels were not independent predictors of 12-month mortality. Independent predictors included older age, elevated heart rate, impaired kidney function and low systolic blood pressure — all of which were associated with low LDL levels.

“Higher LDL cholesterol levels may reflect better nutritional and health status, which are likely related to better tolerance of acute medical stress,” Dr. Jeong and colleagues suggest.

“In conclusion,” they write, “the cholesterol paradox in patients with AMI is related to confounding by baseline characteristics associated with survival.”

Reference:
Low-Density Lipoprotein Cholesterol Level in Patients With Acute Myocardial Infarction Having Percutaneous Coronary Intervention (the Cholesterol Paradox)
Am J Cardiol 2010;106:1061-1068.