Clinical Research Of Large Dose Metoprolol Treatment In Patients With Unstable Angina Pectoris

Objectives1. To study the clinical characteristics and resting heart rate(RHR) in patients with unstable angina pectoris(UAP).2. To evaluate the clinical efficacy, safety and prognosis of large dose metoprolol treatment in patients with UAP of different age groups.3. To investigate the normative of application of β-blockers in patients with UAP.Methods1. A retrospective, observational study was carried out in patients diagnosed with UAP in Qilu Hospital from Jan.2010 to July 2014. The clinical characteristics of each patient was collected and described.2.331 patients of UAP were divided into two levels by age:A level(age<60 years old) and B level(age≥60 years old). Each level was divided into 2 groups, including treatment group A(53 cases) and control group A(72 cases), treatment group B(80 cases) and control group B(126 cases). Besides the treatment of primary diseases, patients in control groups were given routine dose(23.75-47.5mg/d) of metoprolol, while patients in treatment groups were given large dose(71.25-142.5mg/d) of metoprolol. Efficacy and safety of giving large dose of metoprolol in different age levels were evaluated by analyzing the changes of following indicators after patients receiving hospitalization:Canadian Cardiovascular Society(CCS) angina classification, electrocardiogram(ECG) efficacy, blood pressure as well as RHR, incidence of adverse reactions and mortality.3. The normative of application of β-blockers was assessed by the standard-reaching rate of RHR. More possible factors that could affect administration dosage of metoprolol were further explored in this research, and they can provide theoretical foundation for clinical decisions.Results1. A total of 7412 patients with UAP were collected, including 5964 cases of using metoprolol,651 cases of using other β-blockers,797 patients who did not use any β-blockers. No significant differences were observed in sex, age, CCS angina classification, systolic blood pressure, RHR, complications and hospitalization time among four groups(P>0.05). However, there was significant statistical difference on diastolic blood pressure between the different age levels(P<0.05), and no difference within the same age level.2. The efficacy of different dose of metoprolol in each age level:(1) Within the same age level, CCS angina classification in each group reduced obviously after administering metoprolol(P<0.01); compared with the control groups, CCS angina classification in treatment groups were significantly decreased(P<0.01). (2) Systolic blood pressure, diastolic blood pressure and RHR of the 4 groups reduced significantly after metoprolol treatment(P<0.01); there was no difference among other groups(P>0.05), except the systolic blood pressure was significantly different between treatment group A and control group A(P<0.05). (3)In terms of ECG efficacy, total effective rate of treatment group A, control group A, treatment group B and control group B were 56.6%,58.3%,43.7% and 49.2%separately. There was no significant statistical difference between the two groups in each level(P>0.05).3.The efficacy with large dose of metoprolol between different age groups:After treatment, treatment group A and B had no significant statistical difference in CCS angina classification(X2=20719, P=0.437), systolic blood pressure(F=0.805, P=0.371), RHR(F=1.309, P=0.255) and ECG efficacy(X2=2.134, P=0.344).4. The standard-reaching rate of RHR:In the total 331 cases, the standard-reaching rate of RHR rose from 4.23% to 5.74%, but exerted no statistical difference (P>0.05). However, the proportion of patients whose RHR achieving less than 70bmp increased significantly in each group(P<0.05).5. Adverse drug reaction and prognosis:No serious adverse reactions associated with metoprolol were observed in all patients during hospitalization. Mild adverse reactions occurred in 5 cases(1.51%),3 cases of which had nothing to do with metoprolol. There was no significantly difference in all groups(P<0.05). All patients collected in the study got better when they left hospital, without conditions exacerbating and even death during observation.Conclusions1. Large dose of metoprolol in patients with UAP of different age stages can obviously alleviate angina symptoms. Also, it can improve their quality of life and prognosis.2. There is no significant difference in the efficacy of the application of large dose of metoprolol between patients of different age stages.3. The incidence of adverse reactions concerning large dose of metoprolol is low. Large dose of metoprolol ensure its safety when given to patients with UAP, and it can be widely used.4. The clinical application of β-blockers in patients with UAP is not normative, and the standard-reaching rate of RHR is low.