The COMET (Carvedilol or Metoprolol European Trial) showed
better outcomes with Carvedilol compared with Metoprolol tarterate in patients
with ischemic as well as non-ischemic HF, but from study published in Journal of Cardiac Failure
Vol. 18 No. 12 2012, it appears that Metoprolol succinate long acting
preparation is superior to Carvedilol for treating ischemic heart failure and
Carvedilol is superior to Metoprolol succinate for treating non ischemic heart
The deference in efficacy of Metoprolol for ischemic
and Carvedilol for non ischemic heart failure appears to come Patho-physiology
of heart failure in these conditions, Beta -1 receptor density is higher in patients
of ischemic heart failure as compared to non-ischemic heart failure, so Metoprolol
succinate a selective Beta-1 receptor blocker has a edge in treating heart
failure due to ischemia.
Infracted myocardium is denervated so nor-epinephrine
released is less as compared to non-ischemic myocardium; Carvedilol a non
selective blocker; beta-1, beta-2 and alpha blocker reduces myocardial non-epinephrine
levels, has an edge in treating non-ischemic heart failure.
In COMET trial Metoprolol tarterate was used, which is
a short acting drug, with higher peaks and lower troughs, the higher peak
concentrations lead to surges of maximal beta-receptor blockade and loss of
selectivity, and the lower troughs lead to loss of beta-1 blockade and
potential rebound. These fluctuvations may be reason of lesser efficacy of Metoprolol
in ischemic heart failure in COMET study.
Labels: For Doctors, Heart Failure, Intermediate Level