Wednesday, November 14, 2007

ARBs could reduce effort myocardial ischemia

ARBs could reduce effort myocardial ischemia

By Caroline Price - MedwireNews

13 November 2007

Am J Cardiol 2007; 100: 1517-1521

MedWire News: Treatment with the angiotensin receptor blocker (ARB) losartan decreased electrocardiographic measures of ischemia in patients with stable coronary artery disease (CAD), suggesting a possible role for this class of drugs in effort myocardial ischemia, report US researchers.

"Our results showed that losartan 100 mg is able to decrease transient exercise-induced myocardial ischemia by decreasing time to onset of 1-mm ST segment depression, ST-segment depression at peak exercise, and time to recovery of ST-segment depression and increasing exercise duration and maximal workload," report Giancarlo Longobardi (Scientific Institute of Telese Terme, Italy).

The researchers randomly assigned 28 CAD patients to receive losartan 100 mg or placebo for 28 days, followed by 1 week of placebo in both groups and then cross-over to the alternative regimen for a further 28 days.

All patients had reproducible positive exercise test results at the beginning of the study and were normotensive and in sinus rhythm. None of the patients had evidence of left ventricular hypertrophy or conduction defects, or a history of myocardial infarction.

Patients underwent an exercise stress test at the end of each phase of the study.

The results, published in the American Journal of Cardiology, showed that patients' systolic blood pressure (SBP) levels were significantly decreased with losartan compared with placebo (p<0.05). SBP and rate-pressure product were lower after losartan treatment than after placebo at submaximal exercise (both p<0.005), at 1-mm ST depression (p<0.001 and p<0.02, respectively), and at peak exercise (p<0.001 and p<0.005, respectively).

Patients had significantly delayed time to 1-mm ST-depression onset after losartan treatment compared with placebo treatment (479 vs 475 seconds, p<0.01) as well as decreased ST-segment depression at peak exercise (1.3 vs 1.0, p<0.05) and time to recovery of ST-segment depression (120 vs 177, p<0.01).

Furthermore, losartan treatment significantly increased exercise duration (603 vs 565 seconds, p<0.001) and maximal workload (4208 vs 3742 kg, p<0.001) during exercise stress testing compared with placebo.

The team speculates that the mechanism of action, similar to that of nitrates, is likely related to vasodilation in conductive arteries, with a relative decrease in afterload, and vasodilator effects on epicardial and resistance vessels in the coronary circulation.

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