May 7 (HealthDay News) --Lowering blood pressure is essential for reducing the risk of heart disease and stroke, but which drugs are best has been a matter of debate.
Now, two new analyses attempt to answer that question.
Their conclusions: For heart attacks, all antihypertensive drugs work, with the exception of angiotensin receptor blockers (ARBs), probably because there aren't enough studies to confirm their benefit. For stroke, all antihypertensive drugs were better than placebo, but diuretics, ARBs or calcium channel blockers were significantly better than beta blockers or angiotensin-converting enzyme (ACE) inhibitors. Both reports were presented Wednesday at the American Society of Hypertension's annual meeting, in San Francisco.
"Physicians and patients should be reassured that, based on all the world's literature, sliced and diced in many ways, subjected to two separate and distinct types of meta-analyses, antihypertensive drugs do reduce the risk of the two most feared endpoints related to hypertension: heart disease and stroke," said lead researcher Dr. William J. Elliott, a professor of preventive medicine, internal medicine and pharmacology at Rush Medical College in Chicago.
For the first study, Elliott's team analyzed data from 57 trials that looked at treatment for high blood pressure and the reduction of heart attack risk.
The researchers found that, except for ARBs, all drugs were significantly better than placebo or no treatment in lowering blood pressure and reducing the risk of heart disease. Among all the drugs, ACE inhibitors were slightly better, however, the difference was not statistically significant.
These findings confirm other research that has shown that ARBs may not be as effective at preventing heart attack as other blood pressure drugs, and that ACE inhibitors are especially effective at preventing heart disease. That benefit may be due to other effects of the drug, not just its ability to lower blood pressure, the researchers noted.
In addition, this study may help end the debate about which diuretics are best. Elliott's group found that there was no difference among different diuretics in preventing heart attack or sudden cardiac death.
"We presume the lack of significance with ARBs stems from the fact that this is the newest class of drugs, and therefore fewer trials involving fewer patients having fewer coronary heart disease events [half to a third of other classes] limits the statistical power of the analysis," Elliott said.
In the second report, Elliott's team analyzed 60 clinical trials involving 279,371 patients. In their analysis, the researchers also found that blood pressure-lowering drugs were significantly better than placebo or no treatment in reducing the risk of stroke.
Starting treatment with a diuretic reduced the risk of stroke by 55 percent, while beta blockers reduced the risk by about 22 percent, and ACE-inhibitors reduced the risk by about 16 percent. Starting treatment with a diuretic, ARB or calcium channel blocker did not produce significantly different results, the researchers added.
As with the other analyses, there was no significant difference between diuretics in preventing stroke.
"All antihypertensive drug classes are significantly better than placebo/no treatment to reduce the risk of stroke," Elliott said.
Although there are some differences in stroke prevention between the different antihypertensives, the data suggest that diuretics and calcium channel blockers may be more effective in preventing stroke than heart attack.
Dr. Gregg C. Fonarow, a professor of cardiology at the University of California, Los Angeles, does not think these studies answer the question of which blood pressure medication is best. The bottom line is that lowering blood pressure by any means is important in reducing the risk for heart attack and stroke.
"Patients with hypertension are at increased risk for heart attacks and strokes, and reducing blood pressure to goal levels is essential to lower this risk," Fonarow said. "Clinicians and researchers continue to debate whether there are important differences among the specific medications in reducing risk."
These two studies involved pooling together different randomized trials to explore the relative differences for coronary heart disease and stroke risk with different classes of antihypertensive agents, Fonarow said.
"Despite the large number of studies and patients, due to differences in the on-treatment blood pressures achieved in the various studies, something which was not controlled for in these analyses, no firm conclusions can be drawn," Fonarow said. "Furthermore, recent large scale randomized clinical trials where similar blood pressures have been achieved provide entirely different conclusions."
"Achieving and maintaining control of blood pressure to goal levels with lifestyle changes and, when indicated, anti-hypertensive medications is far more important than which specific anti-hypertensive medication is selected," he said.
SOURCES: William J. Elliott, M.D., Ph.D., professor, preventive medicine, internal medicine and pharmacology, Rush Medical College, Chicago; Gregg C. Fonarow, M.D., professor, cardiology, University of California, Los Angeles; May 6, 2009, presentations, American Society of Hypertension annual meeting, San Francisco