HDL: Higher is better

The latest analysis of the data from Treat to New Targets (TNT) Trial shows that higher HDL cholesterol values are associated with reduced risk of heart attack, even in those with low LDL cholesterol values. This counters the argument that some have made that, if a person takes a statin drug, raising HDL adds no additional benefit.

In the 9770-participant trial (randomized, double-blind), participants were given atorvastatin (Lipitor®) 10 mg or 80 mg per day. The study was sponsored by Pfizer, the manufacturer of Lipitor®. All participants were survivors of heart attacks, significant coronary disease by heart catheterization, or had previously undergone coronary angioplasty, stent placement, or bypass surgery—a high-risk group.

At the third month of enrollment, lipid (cholesterol panel) values were obtained and used as the basis for analysis. Participants on 80 mg atorvastatin achieved an average LDL cholesterol (Friedewald) of 77 mg/dl; participants taking 10 mg achieved a level of 101 mg/dl. Using these values, 10.9% of participants taking the higher dose of drug experienced an event, compared to 8.7% on the lower dose (which the investigators called a 22% relative reduction).

However, when the groups were re-analyzed by HDL cholesterol levels, higher HDLs remained predictive of less heart attack and other events, with the group having the highest HDL of ≥55 mg/dl experiencing 25% less events. Most interestingly, this effect was upheld even in participants with very low LDL cholesterols of <70 mg/dl.


Dr. Davis comments:

Though TNT is yet another study from the big-money, wow-them-with-statin-drug benefits genre, it does serve some good purpose.

Although the study was an after-the-fact (post hoc) analysis that did not raise HDL cholesterol by any sort of treatment regimen, it indirectly argues in favor of raising HDL to >55 mg/dl. This is consistent with previous trials suggesting a similar phenomenon.

Of course, this is also consistent with what we advocate in the Track Your Plaque program. Reducing LDL cholesterol with statin drugs is insufficient. Yes, reducing LDL to an average level of 77 mg/dl is associated with less risk, but it does not eliminate risk nor is it associated with regression (reversal) of coronary atherosclerotic plaque.

I see the TNT trial not as validation of the power of Lipitor®, but further validation of the Track Your Plaque targets of 60:60:60—LDL 60 mg/dl, triglycerides 60 mg/dl or less, and HDL 60 mg/dl or greater.

References

Barter P, Gotto AM, LaRosa JC et al. HDL cholesterol, very low levels of LDL cholesterol, and cardiovascular events. N Engl J Med 2007;357:1301–1310.

Copyright 2007, Track Your Plaque.