Niacin, also known as vitamin B3, when combined with statin only therapy for patients with heart and vascular disease does not lower heart attack and stroke risk - a finding which made the National Heart, Lung, and Blood Institute and Abbott Laboratories end a clinical trial 18 months early.
The trial, called AIM-HIGH, was aimed to see whether individuals with heart and vascular disease might have better outcomes if they added niacin to their statin treatment.
The study involved patients who were at risk of suffering a cardiovascular event, such as a stroke or heart attack, even though their low-density lipoprotein (LDL) levels were well controlled. These patients already had a history of cardiovascular disease, and high LDL and triglyceride levels.
Patients with high triglyceride and low HDL levels are known to have a higher risk of experiencing a cardiovascular event. Whether raising HDL levels might improve their outcomes has never been shown.
The trial, involving 3,414 American and Canadian patients, compared patients on statin therapy alone (1,696) to those on statins plus high-dose extended release niacin (1,718). The niacin patients did eventually have higher HDL cholesterol levels, as well as lower blood levels of triglycerides, compared to the statin-only patients.
However, their risk of having a stroke or a heart attack (fatal or non fatal) remained the same, as was their likelihood of having to be admitted to hospital. The study leaders added that the niacin combination patient's chances of requiring a revascularization procedure remained the same too.
All the study participants had a history of cardiovascular disease and had been taking statins to control their LDL levels before the trial began. They all had low HDL and high triglyceride levels - they had a higher-than-normal risk of experiencing future cardiovascular events.
The trial was to last from 2006 till 2012. Patients were aged 64 years (average). 34% of them had diabetes, more than half of them had had a heart attack before the study, 71% had high blood pressure, 81% had metabolic syndrome, and 92% had coronary artery disease.
Acting NHLBI Director, Susan B. Shurin, M.D., said:
"Seeking new and improved ways to manage cholesterol levels is vital in the battle against cardiovascular disease. This study sought to confirm earlier and smaller studies. Although we did not see the expected clinical benefit, we have answered an important scientific question about treatment for cardiovascular disease. We thank the research volunteers whose participation is key in advancing our knowledge in this critical public health area, and the dedicated investigators who conducted the study."
Co-principal AIM-HIGH investigator, Professor Jeffrey Probstfield, M.D., said:
"The lack of effect on cardiovascular events is unexpected and a striking contrast to the results of previous trials and observational studies. The AIM-HIGH findings do not support the trial's hypothesis that, in the population studied, adding extended-release niacin to simvastatin in participants with well-controlled LDL cholesterol can provide additional clinical benefit."
Co-principal AIM-HIGH investigator, Professor William E. Boden, M.D., said:
"The results from AIM-HIGH should not be extrapolated to apply to potentially higher-risk patients such as those with acute heart attack or acute coronary syndromes, or in patients whose LDL cholesterol is not as well-controlled as those in AIM-HIGH."
It appears that the hope that medically raising good cholesterol (HDL) can reduce the risk of heart attack and stroke may be misplaced, according to the surprising results of this study. This trial may change the way millions of patients are treated, experts believe.
The results were surprising because several previous studies that followed up on patients for decades had indicated that those with high HDL cholesterol levels generally live longer and have fewer cardiovascular events compared to those with low HDL levels.
For some patients, there may be a silver lining around the disappointment with niacin. Niacin is not easy to take - it causes headaches and flushing. Many have endured the unpleasant side effects because doctors have told them it may save their lives. Knowing that that is not the case means that they can stop taking it without worrying about any health consequences.
Abbott Laboratories, the makers of niacin, a drug that brought in $927 million in sales last year, will be disappointed.
Abbott put $32 million towards the trial, while the US government gave $21 million.
Several other pharmaceutical companies that have been trying to develop HDL raising drugs will also be unhappy with the results.
Written by Christian Nordqvist