Retrospective analysis showing less cardiac events in post-myocardial infarction patients treated with metoprolol. Secondary Prevention Group

Effects of Metoprolol on Sympathetic Remodeling and Electrical Remodeling at Infarcted Border Zone after Myocardial Infarction in Rabbits

BACKGROUND

The findings of sympathetic remodeling and its electrophysiological implications force us to rerecognize the drugs presently used. The aim of this study was to investigate the effects of metoprolol on sympathetic remodeling and electrical remodeling at the infarcted border zone (IBZ) after myocardial infarction (MI).

METHODS

Forty rabbits were randomly assigned into two groups: MI group (n = 20), ligation of the anterior descending coronary; Metoprolol group (n = 20), ligation of the anterior descending coronary and administration of oral metoprolol 5 mg/kg/day. Eight weeks after surgery, transmural dispersion of repolarization (TDR) at baseline, TDR and difference of TDR (deltaTDR) during sympathetic nerve stimulation were measured at the IBZ. The distribution and densities of growth associated protein 43 and tyrosine hydroxylase positive nerves at the IBZ were detected with immunohistochemical techniques.

RESULTS

The study was completed in the 36 surviving animals (18 rabbits in each group). The densities of growth associated protein 43 and tyrosine hydroxylase positive nerves in the Metoprolol group (2,550 +/- 554 and 1,779 +/- 458 microm2/mm2, respectively) were lower than in the MI group (3,217 +/- 589 and 2,616 +/- 528 microm2/mm2, respectively; both p < 0.01). TDR at baseline, TDR and deltaTDR during sympathetic nerve stimulation were shorter in the Metoprolol group than in the MI group (p < 0.01 for all).

CONCLUSION

Metoprolol can inhibit sympathetic remodeling and electrical remodeling at the IBZ after MI. The association of metoprolol with improved electrical remodeling may be partly related to the inhibition of sympathetic remodeling.

Effect of beta-blockers on the mortality of Japanese patients with myocardial infarction

BACKGROUND

After a myocardial infarction, a higher prevalence of coronary vasospastic response has been reported in the Japanese population than in the Caucasian population. Beta-blockers may exacerbate coronary vasospasm. However, beta-blockers are given to Japanese patients after an acute myocardial infarction, though the mortality benefit is unknown. Thus, we investigated the mortality benefit of beta-blockers given to Japanese patients after an acute myocardial infarction.

METHODS

We prospectively studied consecutive patients with a first myocardial infarction admitted to the coronary care unit of Kansai Medical University Hospital, Osaka, Japan from May 1994 through the end of 2001. Patients who died during hospitalization or who were referred for coronary artery bypass graft surgery were excluded. The association of beta-blocker use with mortality after discharge was assessed by a proportional hazards regression analysis.

RESULTS

There were 546 patients and 400 (73.3%) patients were treated with beta-blockers at the time of discharge from hospital. During a mean follow-up of 2 years, 46 (8.4%) patients died. Beta-blocker therapy was associated with a reduced mortality after adjustment for age, gender, Q wave myocardial infarction, reperfusion therapy during acute phase, Killip functional class, serum creatinine level, cardiovascular risk factors, and medications (hazard ratio=0.51, 95% confidence interval=0.27 to 0.95).

CONCLUSIONS

Contrary to the concern that beta-blocker therapy might induce coronary vasospasm and reduce survival, beta-blocker therapy improved survival after discharge in Japanese patients with a first myocardial infarction.

Efficacy of Calcium Channel Blocker in the Secondary Prevention of Myocardial Infarction-Retrospective Analysis of the 10-Year Prognosis of Coronary Thrombolysis-Treated Patients-

BACKGROUND

Calcium channel blockers (CCBs) may have a positive influence on the long-term prognosis of Japanese patients with ischemic heart disease.

METHODS AND RESULTS

The effect of nifedipine-retard (NR) (n=202) compared with that of non-CCB treatment (n=92) on the secondary prevention of myocardial infarction (MI) was retrospectively investigated in patients who had survived acute MI between 1987 and 1996. The primary endpoint was the occurrence of cardiac death or non-fatal MI. The median follow-up was 6.3+/-2.4 years. The incidence of cardiac events was 8.9% in the NR group and 14.1% in the non-CCBs group (p=0.14, odds ratio (OR): 0.584, 95% confidence interval (CI): 0.286-1,193). However, subanalysis revealed that NR significantly reduced the incidence of cardiac events in patients aged less than 55 years (4.2 vs 18.2%, p=0.016, OR: 0.180, 95%CI: 0.045-0.721) and those who did not smoke (8.6 vs 16.4%, p=0.048, OR: 0.462, 95%CI: 0.203-0.999).

CONCLUSION

Although this was a retrospective analysis, it showed that NR did not cause an increase in the incidence of cardiac events in post-MI patients; it even prevented cardiac events, especially in those who were less than 55 years of age and in non-smokers, suggesting the potential usefulness of CCBs in the secondary prevention of MI in Japan.

Beta-Blockers Prevent Cardiac Events in Japanese Patients With Myocardial Infarction

BACKGROUND

Although the favorable effects of beta-blockers in the treatment of myocardial infarction (MI) have been repeatedly demonstrated in Western countries, administration of this drug has been limited in Japan.

METHODS AND RESULTS

The study group of 1,896 patients with MI was retrospectively divided into 1,029 patients treated by beta-blockers and 867 not treated by beta-blockers, and the incidences of cardiac events, consisting of recurrent MI, death because of worsening heart failure, and sudden death, and cardiovascular events, comprising cardiac events and stroke, were compared in both groups. There were 45 cardiac events (4.4%, 30.1 patients/1,000 patients. year) among the beta-blocker group, which was significantly less than the 56 cardiac events (6.5%, 52.3 patients/1,000 patients. year) among the no-beta-blocker group (p<0.05). The total mortality was 92 (8.9%, 61.6 patients/1,000 patients. year) and 124 (14.3%, 115.8 patients/1,000 patients. year), respectively, and cardiac death occurred in 42 (4.1%, 28.1 patients/1,000 patients. year) and 53 (6.1%, 49.5 patients/1,000 patients. year), respectively, indicating that both these events occurred significantly less in the beta-blocker group (p<0.01 and p<0.05).

CONCLUSIONS

Beta-blockers prevent cardiac events in Japanese patients with MI. However, a placebo-controlled, double-blind, multicenter, clinical trial conducted on a large scale in Japan would further contribute more precise information of the useful effects of beta-blockers.

Pravastatin Reduces the Incidence of Cardiac Events Among Patients With Myocardial Infarction

We retrospectively compared the incidence of cardiac events in myocardial infarction (MI) patients treated in our departments between 1990 and 1999 with pravastatin or without cholesterol-lowering agents. Our aim was to evaluate the efficacy of pravastatin in the secondary prevention of MI. Cardiac events--defined as fatal or nonfatal recurrent MI, sudden cardiac death, and death from congestive heart failure--occurred in 8 (2.2%) of 356 MI patients treated with pravastatin (17.1 cases/1.000 person x year) and in 39 (5.6%) of 700 MI patients not treated with cholesterol-lowering agents (54.3 cases/1000 person x year), which represented a significant decline among those taking pravastatin (P < 0.05, odds ratio: 0.39, 95% (CI: 0.18-0.84). Likewise, total mortality was significantly lower among patients treated with pravastatin (18 cases, 5.1%; 38.4 cases/1,000 person x year vs 77 cases, 11.0%; 107.2 cases/1,000 person x year, P < 0.01, odds ratio: 0.43, 95% CI: 0.25-0.73). Subgroup analysis revealed a significantly lower incidence or cardiac events in the pravastatin group for 6 of the items among 53 patient characteristics, and was lower but not significant for 45 items and was greater but not significant only for 2 items. Furthermore, multivariate analysis confirmed pravastatin to be a useful factor for preventing the occurrence of cardiac events in MI patients (P < 0.05, odds ratio: (0.44, 95% CI: 0.20-0.95), and Kaplan-Meier curves also showed pravastatin to significantly reduce the incidence of both cardiac events and total mortality. These findings are consistent with those previously reported by several large-scale clinical trials carried out in Western countries, and demonstrate that pravastatin is useful for secondary prevention of MI in Japanese patients.

Modification of treatment strategies over a period of 14 years has markedly reduced cardiac events among post-myocardial infarction patients

Recent trends in the treatment of post-myocardial infarction (MI) patients and the factors accounting for the improvement in outcome are presented. A total of 6,602 post-MI patients (5,320 males, 1,282 females; 58.9 +/- 10.4 years of age) enrolled between 1986 and 1999 were followed up for an average of 12.6 +/- 16.3 months. The incidence of cardiac events, which included fatal and nonfatal recurrent MIs, sudden death and death by congestive heart failure, was highest (44.9 events/1,000 person year) in 1986-1987, but decreased steadily to 22.5 events/1,000 person year by 1997-1999 (Trend p<0.0001). This trend accompanied the increased use of coronary thrombolysis, percutaneous transluminal coronary angioplasty and coronary artery bypass graft surgery, increased prescription of antiplatelet agents (51.5%-83.4%), lipid-lowering agents (29.8%-52.6%) and angiotensin-converting enzyme inhibitors (5.3%-->41.0%), and reduced prescription of calcium antagonists (68.5%-41.0%) and nitrates (60.7%-->45.7%). These changes in treatment have led to a decreased incidence of angina pectoris, wall motion abnormalities and abnormal Q waves on electrocardiograms. The decline in the incidence of cardiac events among post-MI patients in the 14 years between 1986 and 1999 reflects implementation of new therapeutic modalities proven to be effective in clinical trials and in daily practice.

Nipradilol can prevent left ventricular systolic and diastolic dysfunction after myocardial infarction in rats

The purpose of this study was to examine the effects of nipradilol on the cardiac function and mRNA expression in Wistar rats with a myocardial infarction (MI) that was created by ligation of the anterior descending coronary. Ten mg x kg(-1) x day(-1) of nipradilol were administrated to the rats in random order, and hemodynamic and Doppler-echocardiographic findings and myocardial mRNA expression were analyzed at 4 weeks after MI. Although left ventricular end-diastolic pressure (LVEDP) and central venous pressure (CVP) were increased in the MI rats, nipradilol significantly reduced the degree of the increase in both parameters. MI also significantly increased the weight of the left and right ventricles, and increased the left ventricular end-diastolic dimension (LVDd), effects that were attenuated by nipradilol. The MI rats showed decreased fractional shortening as systolic dysfunction and decreased E wave deceleration rate as diastolic dysfunction, and nipradilol significantly prevented these. Nipradilol significantly suppressed the increase in the non-infarcted myocardial mRNA expression of atrial natriuretic peptide, brain natriuretic peptide and collagen I and III. In conclusions, nipradilol prevents the cardiac remodeling that is accompanied by systolic and diastolic dysfunction, and inhibits abnormal myocardial gene expression after MI.

Relationship between blood pressure and cardiac events in patients with a healed myocardial infarction

This study investigated the association between blood pressure (diastolic [DBP] and systolic [SBP]) and cardiac events in a total of 6,602 patients with a healed myocardial infarction (MI) (5,320 men, 1,282 women; mean age, 58.9+/-10.4 years), including in-patients and out-patients, from January 1986 to January 1999. The primary endpoints (cardiac events) were recurrent MI (fatal and non-fatal), death from congestive heart failure, or sudden death. The total number of cardiac events was 195 (3.0%) and the incidences of the 3 cardiac events were compared among the 3 DBP groups (DBP low group, <70 mmHg; DBP middle group, 70-89 mmHg; DBP high group, > or =90 mmHg). There were some significant differences in the characteristics of patients among the 3 groups, but no significant difference in cardiac death and total mortality was found among the 3 groups. Cardiac events occurred in 59 of 1,780 patients (3.3%, 33.9/1,000 person years) in the DBP low group, tended to be reduced in number in the DBP middle group (87 of 3,549 patients 2.5%, 21.4/1,000 person years) and were slightly increased in number in the DBP high group (24 of 642 patients 3.7%, 35.2/1,000 person years). Although this correlation between BP and cardiac events appears to be J-shaped, because there is no statistically significant difference in the rate of cardiac events among the 3 groups, we conclude that DBP does not influence the occurrence of cardiac events. The prevalence of cardiac events tended to be greater with a SBP less than 120 mmHg.