This document summarizes the mechanism and evidence for the use of beta blockers. It explains that beta blockers work by blocking beta-1 receptors, which prevents the activation of adenylate cyclase and production of cAMP, reducing calcium influx and the force of cardiac muscle contraction. Two major studies from the 1980s found that beta blockers reduced total mortality by 26-44% in patients who had a heart attack. Beta blockers are also used for other cardiac conditions like arrhythmias, as well as side effects like vivid dreams, fatigue, and erectile dysfunction need to be monitored.
5. Mechanism
โข B1 receptor is part of adenylyl cyclase system
โข When activated AC produces cAMP from ATP
โข cAMP-protien kinase A stimulate- metabolism and
phosphorylate the calcium channel protien- opening of
calcium channel
โข More Calcium enter-cytosolic calcium increase- rate of
breakdown of ATP,ADP &phosphate
โข Increase ATPase activity โincrease rate of contraction
โข Increase activation of troponin Cโincrease force of
contraction
โข Phosphorylation of protien phospholamnab-increase
rate of relaxation
49. Evidence of Beta Blockers post MI
โข Norwegian multicenter study group (1981)
โ17 month follow-up
โPatients presenting with Q-wave MI
โTimolol versus placebo
โ44.6% reduction in sudden death
โ39.3% reduction in total death
โข Beta-blocker heart attack trial (1982)
โ3 years follow-up
โPatients presenting with Q-wave MI
โPropranolol versus placebo
โ26% reduction in total mortality
