Re-evaluation The Effect Of Beta Blockers In Patients With Acute Myocardial Infarction In Reperfusionera

Objective:The objective of this study was to re-evaluation the effect of beta blockers in patients with acute myocardial infarction(AMI), include oral and intrabenous beta blockers. Retrospective study was done in part one of the study to investigate the clinical application of beta-blockers in patients with ST elevation myocardial infarction(STEMI) who endergoing primary percutaneous coronary intervention(p-PCI) in the reperfusion times. Further more, to study the effect of early application of beta-blockers on mortality during hospitalization, reinfarction, angina after infarction, ventricular arrhythmias and cardiac function. In the second part, we investigate the clinical effect of intravenous beta-blocker in treatment of AMI using meta-analysis.Methods:657 patients with STEMI who endergoing p-PCI were enrolled. The mean age was 64 years old(28-90 years old), and the male was 71 %. They were divided into three groups based on beta-blocker ues: early(first 24 hours)(n=228, 37.6 %),delayed(after 24 hours)(n=147, 24.3 %) and no beta-blocker use(n=231, 38.1 %).Logistic regression analysis was done to discuss the effect on early application of beta-blocker. Then, the clinical outcomes were compared between each group. We systematically searched Pub Med, Web of Science and Cochrane Central Register of Controlled Trials(CENTRAL), for trials that randomized studyparticipants to an intravenous beta-blocker versus placebo/standard therapy without a beta-blocker,from established of data base through March, 2015.Results:1. No significant differences in BMI, hypertension, diabetes, stroke, old myocardial infarction(OMI) and history of PCI between each group. While the age of patients in the group of early beta-blocker use were more young, and the proportion of male is higher. The proportion of anterior myocardial infarction(54%) and patients with KillipⅠon admission was higher(p<0.05) in early beta-blocker use group. However,the proportion of the inferior myocardial infarction was higher(p<0.05) and heartrate on admission was slower(p<0.05) in no beta-blocker use group. Meanwhile, the blood pressure on admission was lower(p<0.05) in this group.2. Multiple logistic regression analysis showed that age, blood pressure, heart rate and anterior myocardial infarction were independently associated with early beta-blocker use(p<0.05). Early application of beta-blockers descended with age growth, slow rhythm of heart and hypotension. That was inappropriate in patients with inferior myocardial infarction and KillipⅡor Ⅲ on admission.3. No significant differences in symptoms appearing on admission time,door-to-balloon time(DBT), pre-operation and post-operation TIMI grade and coronary total occlusion(p>0.05). Compared with no beta blocker use group,patients in early and delayed group had higher proportion of left anterior descending branch pathology change, 60.1% and 47.6% respectively. While no beta-blocker use group had higher proportion of right coronary artery pathology change(52.6%).4. Compared with beta-blocker use group, left ventricular end-diastolic diameter(LVDd) was larger and left ventricular ejection fraction(LVEF) was lower in early and delayed application group. The former also showed higher(p<0.05) proportion of segment motion, included hypokinesis(58.9%) and akinesis(67.2%).5. No significant differences in comprehensive results, hospital mortality, myocardial reinfraction, actue heart failure and new-onset atrial fibrillation(AF)(p>0.05)among each group. Angina after infarction showed lower(p<0.05) in early and delayed group, 37.3% and 43.5% respectively. Analysis after adjusted age, sex,symptom onset time, killip grade on admission, infarct area, showed that the incidence rate of angina after infarction was 1.52 times in no BBs use group than that in early BBs use group. Compared with delayed group, early beta-blocker use group had higher proportion of comprehensive results, ventricular tachycardia(VT),ventricular fibrillation(VF) and new-onset AF, and the later two were more obvious.6. In-hospital mortality was reduced 8% with intravenous beta-blockers, RR=0.92(95%CI, 0.86-0.98, P=0.01) when compared with controls. After delete COMMIT study we get the same result. Moreover, intravenous beta-blockade reduced the risk of ventricular tachyarrhythmias(RR=0.75, 95%CI, 0.62-0.90, P=0.002) and myocardial reinfarction(RR=0.76, 95%CI, 0.00-0.86; P < 0.0001) without increasein the risk of cardiogenic shock, heart failure and stroke. However, there is no benefit of infarct size and LVEF, also in sub-acute stage of AMI mortality.7. In subgroup analysis, in-hospital mortality was reduced 16% with intravenous beta-blockers in pre-reperfusion group(RR=0.84, 95%CI, 0.75-0.94, P=0.003),meanwhile reduced the risk of ventricular tachyarrhythmias and myocardial reinfarction without increase in the risk of cardiogenic shock and heart failure.However, there is no mortality benefit in reperfusion group, although the risk of ventricular tachyarrhythmias and myocardial reinfarction was lower compared with controls.Conclusions:1. Early oral beta-blocker in patients with STEMI who undergoing p-PCI were fail to reduce the rate of comprehensive outcomes include in-hospital mortality, myocardial refraction.2. Early beta-blocker use in patients with STEMI who undergoing p-PCI can significantly reduce the rate of angina after infarction, the incidence of VT or VF.3. Early oral beta-blocker use in patients with STEMI may produce negative inotropic action, but the occurrence rate of cardiac insufficiency was not definitely.4. Intravenous beta-blockers early in the course of appropriate patients with AMI appears to be associated with significant reduction in the risk of acute stage cardiovascular outcomes, including all-cause mortality, reinfarction, VT or VF,without increase in the risk of cardiogenic shock and heart failure.5. In pre-reperfusion times, early intravenous beta-blocker use in patients with AMI associated with reduction in the risk of all-cause mortality, reinfarction, VT or VF,without increase in the risk of cardiogenic shock and heart failure. However, there is no mortality benefit in non-acute stage of AMI.6. In reperfusion times, early intravenous beta-blocker use in patients with AMI reduced the risk of reinfarction, VT or VF, without increase in the risk of cardiogenic shock and heart failure. But there is no mortality benefit of AMI.