As a result, several trials have looked at whether statins (a class of drugs used to lower cholesterol levels) could also be effective against AS. Those results have not been promising. Dr. Pibarot and colleagues took another approach, examining medication that is typically used to treat high blood pressure (hypertension).
The renin-angiotensin system (RAS), specifically a molecule called angiotensin II, is a major target for drugs that lower blood pressure. Some hypertension drugs block the production of angiotensin II itself they are known as angiotensin-converting enzyme inhibitors (ACE inhibitors). Other drugs focus on the receptors of angiotensin II angiotensin-receptor blockers (ARBs).
Over three-and-a-half years, Dr. Pibarot's study followed 340 patients who had AS, 73 per cent of whom also had some degree of hypertension. Among the patients, 34 per cent were on ACE inhibitors, 16 per cent were on ARBs, and 50 per cent were on no RAS medication.
The follow-up involved measuring the velocity of the blood across the affected valve. As Dr. Pibarot explains, just as water flows faster when a river narrows, creating rapids, a narrowing valve raises pressure too. "A quicker blood velocity means the stenosis is progressing faster," he says.
Compared to the individuals who were on no medication, those who were on ACE inhibitors had less rapid narrowing of their valve. But the biggest difference was seen in patients on ARBs, where the receptors of angiotensin II are blocked. In those patients, the progress of the disease was slowed considerably three times slower than in the individuals who weren't taking any medication, reports Dr. Pibarot.
In effect, he says that with ARBs the current is slower, like on a calmer river.
In the absen
|Contact: Amanda Bates|
Heart and Stroke Foundation of Canada