Abstract
Acute myocardial infarction remains a leading cause of morbidity and mortality worldwide. Pharmacogenetic and chronotherapeutic approaches are increasingly applied to optimize therapy in chronic cardiovascular diseases. While gene variants are known to influence long-term drug efficacy, their role in modulating drug-induced cardioprotection in acute conditions such as myocardial infarction is unclear. Similarly, the impact of circadian timing on cardioprotective responses remains insufficiently defined. To address these questions, we evaluated metoprolol as a model cardioprotective agent. Here we examine, in a non-pre-specified exploratory analysis of the METOCARD-CNIC trial (NCT01311700), the influence of ADRB1 Arg389Gly polymorphism and the time of AMI onset on metoprolol efficacy. We found that metoprolol reduced infarct size only in patients homozygous for the ADRB1 Arg389 allele, consistent with its genotype-dependent inhibition of neutrophil migration. In-silico docking and binding studies revealed unstable interactions of metoprolol with the Gly389 variant of ADRB1. Moreover, metoprolol was associated with reduced infarct size when AMI onset occurred between 6:00 and 12:00 h. Restricted cardioprotection to the light phase was confirmed in male mice and in neutrophil-specific Adrb1-knockout models. Collectively, these findings highlight the critical roles of genetic background and circadian timing in shaping the efficacy of acute cardioprotective therapies, supporting the rationale for personalized interventions in acute myocardial infarction.