Diuretics improve exercise capacity in patients with congestive heart failure

Diuretics reduce the risk of death, delay heart deterioration and improve exercise capacity in patients with congestive heart failure, a new review of studies shows.

Although widely used for quick relief of CHF symptoms -- cough, shortness of breath and swelling in the feet, legs and ankles -- up until now it was not known whether diuretics had a more substantial effect in treating CHF.

"The available data from several small trials show that in patients with chronic heart failure, conventional diuretics appear to reduce the risk of death and worsening heart failure compared to placebo," according to the review team led by Dr. Rajaa Faris of Saudi Arabia.

Diuretics should be not be the sole medication, rather, they should be used along with other heart medications in treating CHF, the reviewers said.

The review appears in the most recent issue of The Cochrane Library. Systematic reviews draw evidence-based conclusions about medical practice after considering both the content and quality of existing medical trials on a topic.

The researchers looked at data from 525 patients from 14 randomized clinical trials -- seven comparing diuretics with placebo and seven comparing diuretics with other heart medications in treating CHF. The studies involved three types of diuretics: thiazide, potassium-sparing and loop diuretics, such as Lasix. Sixty-one percent of the participants were men with an average age of 59.

The authors estimate that "80 deaths could be avoided for every 1,000 patients treated" with diuretics for CHF, but add that this evidence was based on only 15 deaths out of 221 participants from the studies that reported mortality rates.

CHF, also known as heart failure and cardiac failure, involves a decrease in the heart's ability to pump blood efficiently through the body, leading to a lower delivery of nutrients and oxygen to the cells and causing symptoms such as fatigue, shortness of breath and difficulty with even basic physical activity.

Five million Americans have CHF and 550,000 new cases are diagnosed yearly, according to the American Heart Association. There is no cure or surgical treatment for the disorder and physicians rely on a variety of medications to control symptoms and decrease damage to the heart and other organs in the body while improving patients' quality of life.

But some doctors question whether the benefits of the drugs outweigh the risks. Diuretics can have serious side effects such as depleting electrolytes (potassium and magnesium), which can contribute to irregular heartbeat and kidney disorders.

"Diuretics are effective, easy to administer and inexpensive," said Clyde W. Yancy, M.D., with the University of Texas Southwestern Medical Center in Dallas. "Excessive use of diuretics provokes renal [kidney] insufficiency. Importantly, changes in renal function do impart an additional risk for patients with heart failure."

Proper dosing, Yancy said, is key. "The hope is that physicians will use diuretics in a manner sufficient to relieve evidence of congestion but not to the extent that the risks of disturbance of electrolytes and renal function occur.

"Few drugs are as immediately effective for heart failure as diuretics," Yancy added. "Any patient in whom these drugs are prescribed should feel at ease with the therapy, provided they are under the care of a team of health care professionals who are actively evaluating electrolyte balance and kidney function."

The Cochrane reviewers say that many of the studies they analyzed were small, with varying types and doses of diuretics compared, and that further research is needed to understand the optimal use and benefits of diuretic treatment

A large, long-term study of diuretic treatment for older adults with high blood pressure in a recent American Journal of Cardiology found that although those on the drug had a slightly higher risk of developing diabetes, the death rate from heart attack or stroke was significantly reduced.