Taking Blood Pressure Medication Reduces Risk of Heart Failure, Too

High blood pressure can double a person's risk for congestive heart failure, according to the American Heart Association. In addition, patients with congestive heart failure have a four-times higher mortality risk. Now, a new study has found that antihypertensive medications not only help reduce high blood pressure, they also appear to reduce the risk of congestive heart failure.

The study used participants who were part of another ongoing study, called the Losartan Intervention for Endpoint Reduction in Hypertension (LIFE) Study. Participants in the LIFE study were randomly assigned to receive the antihypertensive medication, losartan (an angiotensin II receptor blocker), or atenolol (a beta-blocker).

Echocardiograms were used in the current study to measure heart wall thickness and ventricular filling in 728 patients with high blood pressure and enlarged hearts. The 728 patients were reevaluated one year later using another echocardiogram.

The researchers looked, in particular, at changes in left ventricular diastolic filling and its association with regression in left ventricular hypertrophy when patients took antihypertensive medication. Diastolic dysfunction in the left ventricle, the heart's main pumping chamber, causes 40 percent of congestive heart failure in older people, according to the researchers.

How Does the Heart Work?

The cardiovascular system, composed of the heart and blood vessels, is responsible for circulating blood throughout your body to supply the body with oxygen and nutrients.

The heart is the muscle that pumps blood filled with oxygen and nutrients through the blood vessels to the body tissues. It is made up of:

• Four chambers (two atria and two ventricles) that receive blood from the body and pump out blood to it.
  
  
  • The atria receive blood coming back to the heart.
    
    
  • The ventricles pump the blood out of the heart.
    
    
• Blood vessels, which compose a network of arteries and veins that carry blood throughout the body.
  
  
• Four valves to prevent backward flow of blood.
  
  
• An electrical system of the heart that controls how fast it beats.

What Is Diastolic Ventricular Dysfunction?

Diastolic ventricular dysfunction means that the left ventricle does not fill properly during the relaxed (diastolic) phase of the heart's pumping action. The left ventricle muscle becomes thickened, making it stiffer and unable to fully relax. As the left ventricle cannot fill completely, too little blood is pumped by the left side of the heart, while the right side pumps normally.

The heart, at first, tries to compensate for the ventricular dysfunction by enlarging (so more blood can be pumped), developing more muscle mass (so the heart can pump more strongly), or by pumping faster (to increase output of the heart).

Eventually, diastolic ventricular dysfunction can result in the lungs filling with blood, which can lead to pulmonary edema and death.

The Study's Findings

• Blood pressure was reduced by an average of 23 mm Hg systolic and 11 mm Hg diastolic after one year of antihypertensive treatment.
  
  
• Left ventricular heart mass was reduced by 10 percent on average, leading to improved blood flow into the left ventricle.
  
  
• Normal left ventricular filling increased from 15 percent of the patients at baseline to 26 percent of the patients after one year.
  
  
• Abnormal left ventricular relaxation decreased to 57 percent of the patients after one year of treatment.
  
  
• Patients with a reduction or regression in left ventricular mass also experienced improvement in their heart's ability to relax as stiffness was reduced.
  
  
• In patients with reduced left ventricular mass, left ventricular relaxation time was decreased from 116 milliseconds (ms) at baseline to 104 ms after one year.

Since the LIFE study is ongoing, the researchers of the current study do not know which of the two antihypertensive medications each patients was taking. Thus, it is unknown at this time whether losartan or atenolol is more effective.

The study was published in a recent issue of Circulation, a journal of the American Heart Association.

Always consult your physician for more information.

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