JANUARY 15, 2005

CCB plus ACE is a winning combination for hypertension

ASCOT's results are out — and it's not a tie. The combo is head and shoulders
above the current beta-blocker/thiazide treatment

Few things can make Benjamin Quirell's blood pressure jump like the final seconds of the Kentucky Derby. Unfortunately, the 52-year old horse racing enthusiast is hypertensive to begin with. The combo of beta-blocker and thiazide diuretic his doctor has him on do a decent job of keeping his blood pressure down most of the time, but when it comes to horse racing, he needs something with a little more oomph. Fittingly, ASCOT — the Anglo-Scandinavian Cardiac Outcomes Trial of antihypertensive treatments — has the answer. The trial was started in 1997 but was stopped early after a new combination therapy achieved markedly better results than the standard beta-blocker/thiazide diuretic combo.

The ASCOT trial, involving 19,343 patients, tested a regimen of the beta-blocker, atenolol, and the thiazide diuretic, bendroflumethiazide, against a novel combination of the calcium channel blocker, amlodipine, and the angiotensin converting enzyme (ACE) inhibitor, perindopril.

The full results will not be made public until March, but researchers claim that the new amlodipine-perindopril combination offered such significant benefits over atenolol with bendroflumethiazide that the trial steering committee ordered the research halted on November 18, 2004. The trial had been due to continue until 2006.

This is the second and final arm of the ASCOT study. The first, the lipid control arm, measuring atorvastatin against placebo, was also stopped early after the statin demonstrated significant benefits. In that case, the trial was stopped after researchers found a risk reduction over placebo of roughly one-third for all stroke, heart attack and fatal coronary heart disease, and a risk reduction in overall cardiovascular mortality of about 10%.

"The results of the ASCOT trial have been long awaited," said Dr Peter Sever, from Imperial College London, co-chairman of the study. "It was really the first trial to specifically look at a combination of drugs. Most patients require more than one treatment so it is silly to test single drugs."

"The results were so significant that it was important to stop a trial early because of important cardiovascular benefits to those patients receiving newer drugs," he said. He added that most patients would be advised to switch at followup appointments, but cautioned against stopping beta-blockers too abruptly as this could cause high blood pressure to rebound.

Discussing the poorer performance of atenolol and bendroflumethiazide, Dr Sever said: "The implication is that the very commonly used beta-blocker drugs are not as effective at preventing the major complications of hypertension — strokes and heart attacks and so on."

Indeed, it might be fair to ask if the trial tells us more about the strengths of amlodipine with perindopril, or about the weaknesses of atenolol. A Swedish study published in The Lancet this past November found atenolol little better than placebo at controlling blood pressure, and the authors expressed doubts about the suitability of atenolol as a reference drug in hypertension studies. Concern is also growing among cardiologists that atenolol could increase blood sugar levels and even provoke diabetes. Hopefully, the full results of the ASCOT study will shed further light on this question.



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