College of Cardiology 60th Annual Scientific Sessions
NEW ORLEANS — Combination therapy with olmesartan
and a calcium channel blocker was associated with similar rates of
cardiovascular events and mortality when compared with a high-dose angiotensin
II receptor blocker alone in patients with cardiovascular disease. However,
dual therapy appeared inferior to angiotensin II receptor blocker monotherapy
in patients with diabetes, according to results of the OSCAR study.
High-dose angiotensin II receptor blockers (ARBs) are
more effective than low-dose ARBs for the prevention of CVD in patients with
diabetic nephropathy or heart failure; however, the question of whether
combination therapy with an ARB plus a calcium channel blocker (CCB) is
superior to ARB monotherapy remains unanswered.
Hisao Ogawa, MD, PhD, professor in the department
of CV medicine at Kumamoto University in Japan, and colleagues aimed to address
this question by initiating the Olmesartan and Calcium Antagonists Randomized
“The OSCAR Study is the first single trial in the
world to examine the effect of high-dose ARB and ARB plus CCB in high-risk
elderly patients,” Ogawa said during a press conference here.
Between June 2005 and May 2007, Ogawa and colleagues
recruited 1,164 high-risk patients aged 65 to 84 years from 134 institutions in
Japan. To qualify for inclusion, patients had to have uncontrolled blood
pressure despite receiving treatment with the ARB olmesartan (Benicar, Daiichi
Sankyo) and CVD or type 2 diabetes. The study’s primary endpoint was a
composite of CV events, including cerebrovascular disease, coronary artery
disease, HF, other atherosclerotic diseases, diabetic microvascular diseases
and renal dysfunction, as well as all-cause mortality.
Patients were randomly assigned to receive daily
high-dose olmesartan (40 mg) or a CCB plus olmesartan (20 mg). At 36 months,
adequate blood pressure control was observed in both treatment groups. However,
compared with monotherapy, combination therapy induced considerably greater
decreases in BP, according to the researchers. Mean systolic BP was a mean 2.4
mm Hg lower and mean diastolic BP 1.7 mm Hg lower.
The researchers noted no significant differences between
the two treatment arms in the number of primary endpoints. Fifty-eight events
occurred in the monotherapy group vs. 48 in the combination group (HR=1.31; 95%
Results of a subgroup analysis, however, revealed a
statistically significant difference between treatment groups in patients with
pre-existing CVD. Patients assigned to combination therapy experienced
considerably fewer CV events and death compared with those assigned monotherapy
(24 vs. 51; HR=1.63; 95% CI, 1.06-2.52).
In addition, a second subgroup analysis indicated a
higher rate of the primary outcome between treatment arms in patients with
diabetes only, with 14 events occurring in the combination group and seven
occurring in the ARB monotherapy group (HR=0.52, 95% CI, 0.21-1.28). The
researchers also noted a significant treatment-by-subgroup interaction for the
primary endpoints between patients with CVD and patients with diabetes only.
These results suggest that the relative effect of the
two therapies is dependent on the presence of CVD or diabetes, according to the
researchers. – by Melissa Foster
Disclosure: Dr. Ogawa received grant support during the last 5
years from Astellas, AstraZeneca, Bayer, Boehringer Ingelheim, Daiichi Sankyo,
Eisai, Kowa, Kyowa Hakko Kirin, MSD, Novartis, Pfizer, Sanofi Aventis,
Schering-Plough and Takeda.
For more information:
- Ogawa H. LBCT IV 3015. Presented at: ACC 60th Annual Scientific
Sessions; April 2-5, 2011; New Orleans.
It is interesting to see how different subgroups seem to benefit
differently from different antihypertensive medicines. I think that people
really do need to take into consideration the patient’s individual profile
before deciding which drugs to use and which combination of antihypertensive
treatments because many patients need more than one drug. That’s bottom
– Byron Lee, MD
Associate Professor of Medicine
California, San Francisco
Disclosure: Dr. Lee reports no relevant financial disclosures.