Dose of metoprolol CR/XL and clinical outcomes in patients with heart failure: analysis of the experience in metoprolol CR/XL randomized intervention trial in chronic heart failure (MERIT-HF).
OBJECTIVE
We performed a post-hoc subgroup analysis in the Metoprolol CR/XL Randomized Intervention Trial in Chronic Heart Failure (MERIT-HF) with the aim of reporting on the heart rate (HR) response during the titration phase and clinical outcomes from the three-month follow-up visit to end of study in two dosage subgroups: one that had reached more than 100 mg of metoprolol CR/XL once daily (high-dose group; n = 1,202; mean 192 mg) and one that had reached 100 mg or less (low-dose group; n = 412; mean 76 mg).


BACKGROUND
Clinicians have questioned whether patients need to reach the target beta-blocker dose to receive benefit. METHODS; Outcome (Cox-adjusted) was compared with all placebo patients with dose available at the three-month visit (n = 1,845).


RESULTS
Data indicated somewhat higher risk in the low-dose group compared with the high-dose group. Heart rate was reduced to a similar degree in the two dose groups, indicating higher sensitivity for beta-blockade in the low-dose group. The reduction in total mortality with metoprolol CR/XL compared with placebo was similar: 38% (95% confidence interval [CI], 16 to 55) in high-dose group (p = 0.0022) and also 38% (95% CI, 11 to 57) in the low-dose group (p = 0.010).


CONCLUSIONS
Risk reduction was similar in the high- and low-dose subgroups, which, at least partly, may be the result of similar beta-blockade as judged from the HR response. The results support the idea of an individualized dose-titration regimen, which is guided by patient tolerability and the HR response. Further research is needed to shed light on why some patients respond with a marked HR reduction and reduced mortality risk on a relatively small dose of a beta-blocker.
Wallenberg Laboratory for Cardiovascular Research, Sahlgrenska University Hospital, Göteborg, Sweden. john.wikstrand@wlab.gu.se
John
J
Wikstrand
Ake
A
Hjalmarson
Finn
F
Waagstein
Björn
B
Fagerberg
Sidney
S
Goldstein
John
J
Kjekshus
Hans
H
Wedel
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage* / Q000097:blood; D000368:Aged; D002908:Chronic Disease; D004305:Dose-Response Relationship, Drug; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications / Q000188:drug therapy* / Q000401:mortality; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D015994:Incidence; D008297:Male; D008790:Metoprolol / Q000008:administration & dosage* / Q000031:analogs & derivatives* / Q000097:blood; D008875:Middle Aged; D009203:Myocardial Infarction / Q000150:complications / Q000188:drug therapy / Q000401:mortality; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome; D028761:Withholding Treatment
D000319:Adrenergic beta-Antagonists; D008790:Metoprolol