Effect of Combination Therapy With Simvastatin and Carvedilol in Patients With Left Ventricular Dysfunction Complicated With Acute Myocardial Infarction Who Underwent Percutaneous Coronary Intervention

Additive effects of β-blockers on renin-angiotensin system inhibitors for patients after acute myocardial infarction treated with primary coronary revascularization

BACKGROUND

Although some β-blockers are effective for patients after acute myocardial infarction (AMI), few studies have compared their additive effects on renin-angiotensin system inhibitors (RAS-Is).

METHODS AND RESULTS

The 251 consecutive AMI patients administered angiotensin-converting-enzyme inhibitors (ACE-Is) or angiotensin-II receptor blockers (ARBs) were retrospectively investigated and divided into 2 groups: treated without β-blockers (no-β-blocker group, n=80) or treated with β-blockers before discharge (β-blocker group, n=171; carvedilol [n=91] or bisoprolol [n=80]). The doses of RAS-Is used for patients in the no-β-blocker group were at least double those used in the β-blocker group. No significant differences between the 2 groups were observed with regard to baseline characteristics. After a 12-month follow-up, the survival and cardiac event-free rates in the β-blocker group were significantly higher than those in the no-β-blocker group. The percent change in blood pressure did not significantly differ between the 2 groups, but the levels of brain natriuretic peptide, metalloproteinase-2, and metalloproteinase-9 and the left ventricular ejection fraction improved significantly in the β-blocker group compared with the no-β-blocker group. Regarding the 2 β-blockers, carvedilol treatment produced more favorable outcomes than bisoprolol.

CONCLUSIONS

The data suggest that treatment with RAS-I in combination with β-blocker is more effective for patients after AMI than treatment with RAS-I alone.

Reperfusion injury as a therapeutic challenge in patients with acute myocardial infarction

Cardiomyocyte death secondary to transient ischemia occurs mainly during the first minutes of reperfusion, in the form of contraction band necrosis involving sarcolemmal rupture. Cardiomyocyte hypercontracture caused by re-energisation and pH recovery in the presence of impaired cytosolic Ca(2+) control as well as calpain-mediated cytoskeletal fragility play prominent roles in this type of cell death. Hypercontracture can propagate to adjacent cells through gap junctions. More recently, opening of the mitochondrial permeability transition pore has been shown to participate in reperfusion-induced necrosis, although its precise relation with hypercontracture has not been established. Experimental studies have convincingly demonstrated that infarct size can be markedly reduced by therapeutic interventions applied at the time of reperfusion, including contractile blockers, inhibitors of Na(+)/Ca(2+) exchange, gap junction blockers, or particulate guanylyl cyclase agonists. However, in most cases drugs for use in humans have not been developed and tested for these targets, while the effect of existing drugs with potential cardioprotective effect is not well established or understood. Research effort should be addressed to elucidate the unsolved issues of the molecular mechanisms of reperfusion-induced cell death, to identify and validate new targets and to develop appropriate drugs. The potential benefits of limiting infarct size in patients with acute myocardial infarction receiving reperfusion therapy are enormous.