According to observational studies, increasing the level ofhigh-density lipoprotein (HDL) or good cholesterol reduces the riskof heart attack. But is the association really true? But a study published today (May 17) in The Lancet suggests that a high HDL cholesterol level need not necessarilylower the risk of suffering from a heart attack. If HDL is indeed a true plasma biomarker of an underlyingpathological process (heart attack), then an increase in thisbiomarker should result in reduced risk of heart attack. To test this, the researchers used a particular randomisation(mendelian randomisation) to check if people carrying a well knowninherited gene variant (LIPG 396Ser) that is known to inherentlyincrease the HDL level actually were at reduced risk of heartattack. The proof They found that people who had the variant had a higher HDL levelbut that did not result in reduced risk. Komatsu Turbocharger
This came out by analysing 21,000 people who had suffered a heartattack and 95,000 controls (those who had not suffered an attack)from 20 studies. Moreover, they constructed a genetic risk score for the 14 commonsingle nucleotide polymorphisms (SNPs) that are commonly associatedwith HDL cholesterol and tested this score in nearly 12,500 peoplewith a history of heart attack and over 41,000 controls. The score did not show any high HDL level-low risk association,either. Simultaneously, they put the 13 common SNPs that are”exclusively” associated with LDL cholesterol (badcholesterol) through the same test and found that low LDL level didlower the risk. “These results challenge several established views aboutplasma HDL cholesterol,” they write. China Turbo Charger Cartridge
“First, these dataquestion the concept that raising plasma HDL cholesterol shoulduniformly translate into reductions in risk of myocardialinfarction.” Their conclusion, which is particularly linked to the gene variant(LIPG 396Ser), is that increasing the HDL level will not result ina positive clinical outcome. Other ways of increasing the HDL levels have been tried earlier buthave not achieved the desired result. For instance, the authors cite the instance of increasing the HDLlevel by resorting to hormone replacement therapy in randomisedcontrolled trials. Though the HDL level did increase, it did notproduce a concomitant reduction in heart attack risk. The same randomisation used in this study was used even earlier andthe outcome was the same — high HDL level did not mean lowrisk of heart attack. China Cummins Turbo Kits
Hence the authors assert that “interventions (lifestyle orpharmacological) that raise plasma HDL cholesterol cannot beassumed ipso facto to lead to a corresponding benefit with respect to risk ofmyocardial infarction.” However, the gene variant the authors used is rare in thepopulation. Hence it may not serve as a strong indicator. But as the Comment piece accompanying the Lancet article mentions, the study was robust and “any negativeassociation [as seen in this study] can be regarded asdefinite.” Clinical limitation But the second salvo by the authors of the study is critical forclinical settings. They warn that using the plasma biomarker (HDLlevel) as a “surrogate measure for risk of heartattack” has some limitations. However, more studies and re-evaluations are needed before the highHDL level-low risk of heart attack assumption is dismissedaltogether.
In short, the search for the true biomarkers for coronary heartdisease has begun in full earnest.