NEW ORLEANS – In the 10-year follow-up of a study in patients with stable coronary artery disease, the ratio of triglycerides to high-density lipoproteins was highly predictive of major adverse cardiovascular events (MACE).
Dr. Raul D. Santos of the Heart Institute at the University of Sao Paulo Medical School Hospital in Brazil reported the analysis, which was part of the Medical, Angioplasty, or Surgery Study (MASS-II). That study compared the long-term effects of medical treatment, angioplasty, or surgical strategies in patients with stable angina symptoms of multivessel coronary artery disease (CAD) and preserved ventricular function, determining that surgery was the optimal approach in this patient subset (J. Am. Coll. Cardiol. 2004;43:1743-51)
“After 10 years of follow-up of stable CAD patients in MASS-II, the TG/HDL [triglyceride/high-density lipoprotein] ratio was the only lipid parameter independently associated” with major adverse cardiovascular events (MACE), Dr. Santos reported in the poster presentation.
The study randomly assigned 611 patients to coronary artery bypass grafting (CABG), percutaneous coronary intervention (PCI), or medical therapy. Lipid-modifying therapies were equally instituted in all study patient groups. Concentrations of total cholesterol, high-density lipoprotein (HDL), non-HDL cholesterol, and low-density lipoprotein (LDL) cholesterol, as well as LDL/HDL and TG/HDL ratios, were divided according to distribution quartiles. The associations between MACE occurrence and plasma lipids at baseline and at 6 months, as well as other risk factors and randomized CAD treatment, were determined by Cox regression models.
Mean levels of lipids were 150 mg/dL for TG, 37 mg/dL for HDL cholesterol, and 140 mg/dL for LDL cholesterol.
“LDL was not well treated at the time this study began 11 years ago. Only about one third of patients were on statins, and mean levels were about 140 mg/dL,” Dr. Santos said. “Yet, even in these patients with high LDL, the TG/HDL ratio was a marker for later events.”
In the MASS-II patients followed for an average of 11.4 years (range 9-15 years), MACE were observed in 42% of the PCI arm, 59% of the medical therapy arm, and 33% of the CABG arm.
After adjustment for confounders, the investigators found the following factors to be independently associated with MACE: age greater than 65 years, randomization to CABG versus medical therapy, systemic arterial hypertension, and TG/HDL ratio determined at 6 months.
For the TG/HDL ratio, the hazard ratio for the occurrence of MACE, comparing the highest and lowest quartiles of the ratios, was significant at 1.57 (P = .015). Hazard ratios for the third versus first quartiles was 1.38 (P = .098) and for the second versus first quartiles was 0.83 (P = .445). No association was found between MACE and other plasma lipids.
Among patients with a TG/HDL ratio greater than 6, only about 45% of patients were free of MACE at 10 years, compared with greater than 70% for those with a TG/HDL ratio of less than 3.
“The TG/HDL ratio is a marker of residual risk,” Dr. Santos said. “For clinicians, this means that you treat the LDL, of course, but you need to look at triglycerides and HDL. While the lab doesn’t give you this ratio, it’s very easy to calculate.”
Dr. Gerald S. Berenson of Tulane University School of Medicine, New Orleans, and principal investigator of the Bogalusa Heart Study, viewed the poster with interest. “This is very important information,” he said. “The TG/HDL ratio is so easy to measure. Everyone is looking at particle size, and so forth, but we routinely get these levels, so you just need to look at the ratio. It’s a good measure of insulin resistance as well.”
Dr. Santos has served on the speakers bureaus of Novartis, Merck, Biolab, and Bristol-Myers Squibb. Dr. Berenson had no relevant conflicts of interest.