(RxWiki News) Not all heart failure patients are created equal. Some have more severe symptoms, and some are more stable. So researchers need to learn whether medications work in each subgroup of patients.
A recent study looked at the use of RAS antagonists in heart failure patients whose hearts were pumping out a mostly stable amount of blood to the body. RAS antagonists include ACE inhibitors and ARBs.
The study found that more of the patients who received RAS antagonists survived at the end of one year.
"Ask a cardiologist questions about your treatment."
The study, led by Lars H. Lund, MD, PhD, of the cardiology department at the Karolinkska Institutet in Stockholm, Sweden, investigated whether renin-angiotensin system (RAS) antagonists reduce the death rate among patients with heart failure and preserved ejection fraction.
Examples of RAS antagonists include angiotensin-converting enzyme (ACE) inhibitors and angiotensin receptor blockers (ARBs).
Ejection fraction refers to how much blood is pumped out of the heart's ventricles to the rest of the body during each heartbeat. "Preserved" ejection fraction means that this amount is remaining steady instead of decreasing, which is riskier for the patient.
As Sarah Samaan, MD, a cardiologist with Legacy Heart Center in Dallas-Fort Worth, explained, some people with congestive heart failure do not have a weak heart muscle. Instead, they have a "normal heart strength but a very stiff, inflexible heart muscle." These are the patients likely to have "preserved ejection fraction."
"This makes it harder for the heart to fill with blood during its natural relaxation phase, and thus fluid may back up into the lungs, causing shortness of breath and weakness, especially with exercise," Dr. Samaan said. "High blood pressure, atrial fibrillation, and obesity are common causes of this type of heart failure."
In this study, Dr. Lund and his colleagues began with 41,791 Swedish heart failure patients seen at 148 clinics or hospitals from 2000 to 2011. They focused on the 16,216 patients, average age 75, who had at least 40 percent ejection fraction. These patients with preserved ejection fraction are in a lower risk group than those with reduced ejection fraction.
Within this group, 12,543 were treated with RAS antagonists, and the other 3,673 were not. The researchers compared the outcomes for these two groups by matching patients according to age and other risk factors.
The results of the matched comparisons found that 77 percent of the patients treated with RAS antagonists survived for one year, compared to 72 percent of those not treated with the RAS antagonists. When not taking age and other risk factors into account, the unadjusted one-year survival rate for treated patients was 86 percent compared to 69 percent in the untreated group.
The researchers therefore concluded that treating heart failure patients with preserved ejection fraction with RAS antagonists reduced the death rate for up to one year. The patients were not studied beyond one year in this analysis.
"These drugs have been proven to help patients with congestive heart failure caused by a weak heart muscle, but it's always been somewhat debatable whether the drugs make a substantial difference in patients with congestive heart failure who do not have weak hearts," Dr. Samaan said.
"While this study is not a game changer, physicians caring for patients with this form of congestive heart failure may now be more apt to make the choice to prescribe one of these drugs instead of another of the many options available," she said.
The study was published November 27 in JAMA. The research was funded by the Swedish National Board of Health and Welfare, the Swedish Association of Local Authorities and Regions, the Swedish Society of Cardiology and the Swedish Heart-Lung Foundation.
Dr. Lund also received grants from the Stockholm County Council and from AstraZeneca for this study. He also has previously received grants from AstraZeneca, Thoratec and Heart-Ware.