Alternative hypothesis for efficacy of macrolides in acute coronary syndromes

Clarithromycin-induced Coronary Vasospasms Caused Acute Coronary Syndrome in a 19-year-old Male Patient

A 19-year-old-man was admitted to our hospital with intermittent chest pain. The day before admission, he had been diagnosed with enteritis and prescribed clarithromycin. He had experienced severe chest pain three times after taking clarithromycin; thus, acute coronary syndrome (ACS) was suspected. Emergent coronary angiography showed normal coronary arteries; however, the result of a subsequent acetylcholine provocation test was positive. We diagnosed him to have ACS caused by coronary vasospasms and suspected clarithromycin-induced Kounis syndrome. Although more common in older patients, Kounis syndrome must be suspected and a thorough medication history should be taken whenever a patient complains of chest pain.

Atherosclerosis: process, indicators, risk factors and new hopes

Background:

Atherosclerosis is the major cause of morbidities and mortalities worldwide. In this study we aimed to review the mechanism of atherosclerosis and its risk factors, focusing on new findings in atherosclerosis markers and its risk factors. Furthermore, the role of antioxidants and medicinal herbs in atherosclerosis and endothelial damage has been discussed and a list of important medicinal plants effective in the treatment and prevention of hyperlipidemia and atherosclerosis is presented.

Methods:

The recently published papers about atherosclerosis pathogenesis and herbal medicines effective in the treatment and prevention of hyperlipidemia and atherosclerosis were searched.

Results:

Inflammation has a crucial role in pathogenesis of atherosclerosis. The disease is accompanied by excessive fibrosis of the intima, fatty plaques formation, proliferation of smooth muscle cells, and migration of a group of cells such as monocytes, T cells, and platelets which are formed in response to inflammation. The oxidation of low density lipoprotein (LDL) to Ox-LDL indicates the first step of atherosclerosis in cardiovascular diseases. Malondialdehyde factor shows the level of lipoperoxidation and is a sign of increased oxidative pressure and cardiovascular diseases. In special pathological conditions such as severe hypercholesterolemia, peroxynitrite concentration increases and atherosclerosis and vascular damage are intensified. Medicinal plants have shown to be capable of interacting these or other pathogenesis factors to prevent atherosclerosis.

Conclusions:

The pathogenesis factors involved in atherosclerosis have recently been cleared and the discovery of these factors has brought about new hopes for better prevention and treatment of atherosclerosis.

Clarithromycin for 2 weeks for stable coronary heart disease: 6-year follow-up of the CLARICOR randomized trial and updated meta-analysis of antibiotics for coronary heart disease

OBJECTIVES

We have reported increased 2.6-year mortality in clarithromycin- versus placebo-exposed stable coronary heart disease patients, but meta-analysis of randomized trials in coronary heart disease patients showed no significant effect of antibiotics on mortality. Here we report the 6-year mortality of clarithromycin- versus placebo-exposed patients and updated meta-analyses.

METHODS

Centrally randomized, placebo controlled multicenter trial. All parties were blinded. Analyses were by intention to treat. Meta-analyses followed the Cochrane Collaboration methodology.

RESULTS

We randomized 4,372 patients with stable coronary heart disease to clarithromycin 500 mg (n = 2,172) or placebo (n = 2,200) once daily for 2 weeks. Mortality was followed through public register. Nine hundred and twenty-three patients (21.1%) died. Six-year mortality was significantly higher in the clarithromycin group (hazard ratio 1.21, 95% confidence interval 1.06-1.38). Adjustment for entry characteristics (sex, age, prior myocardial infarction, center, and smoking) did not change the results (1.18, 1.04-1.35). Addition of our data to that of other randomized trials on antibiotics for patients with coronary heart disease versus placebo/no intervention (17 trials, 25,271 patients, 1,877 deaths) showed a significantly increased relative risk of death from antibiotics of 1.10 (1.01-1.20) without heterogeneity.

CONCLUSIONS

Our results stress the necessity to consider carefully the strength of the indication before administering antibiotics to patients with coronary heart disease.

Randomised placebo controlled multicentre trial to assess short term clarithromycin for patients with stable coronary heart disease: CLARICOR trial

OBJECTIVE

To determine if the macrolide clarithromycin affects mortality and cardiovascular morbidity in patients with stable coronary heart disease.

DESIGN

Centrally randomised multicentre trial. All parties at all stages were blinded. Analyses were by intention to treat.

SETTING

Five Copenhagen University cardiology departments and a coordinating centre.

PARTICIPANTS

13,702 patients aged 18 to 85 years who had a discharge diagnosis of myocardial infarction or angina pectoris in 1993-9 and alive in August 1999 were invited by letter; 4373 were randomised.

INTERVENTIONS

Two weeks' treatment with clarithromycin 500 mg/day or matching placebo.

PRIMARY OUTCOME

composite of all cause mortality, myocardial infarction, or unstable angina pectoris during three years' follow-up. Secondary outcome: composite of cardiovascular mortality, myocardial infarction, or unstable angina pectoris. The outcomes were obtained from Danish registers and were blindly assessed by the event committee.

RESULTS

2172 participants were randomised to clarithromycin and 2201 to placebo. We found no significant effects of clarithromycin on the primary outcome (hazard ratio 1.15, 95% confidence interval 0.99 to 1.34) or secondary outcome (1.17, 0.98 to 1.40). Mortality was significantly higher in the clarithromycin arm (1.27, 1.03 to 1.54; P = 0.03) as a result of significantly higher cardiovascular mortality (1.45, 1.09 to 1.92; P = 0.01).

CONCLUSIONS

Short term clarithromycin in patients with stable coronary heart disease may cause significantly higher cardiovascular mortality. The long term safety of clarithromycin in patients with stable ischaemic heart disease should be examined. Trial registration ClinicalTrials.gov NCT00121550.

Chlamydia pneumoniae and coronary artery disease: the antibiotic trials

Parallel with the mounting evidence that atherosclerosis has a major inflammatory component, provoking agents that may initiate and drive this process have been sought. Infectious agents such as Chlamydia pneumoniae have been alleged to be activators of inflammation that may contribute to atherosclerosis and thus coronary artery disease (CAD) and its associated complications. A logical pneumoniae extension of this theory whether treating C pneumoniae infection with antibiotics and/or modulating inflammatory processes can affect CAD and its sequelae. This article discusses the potential role of C pneumoniae in atherosclerosis, its detection, and the rationale for antibiotics. Additionally, it summarizes the current randomized clinical trials of antichlamydial antibiotics in patients with CAD and draws conclusions based on the results.

No causal association between inflammation and Chlamydia pneumoniae in patients with chronic ischemic arterial disease

The C-reactive protein, Chlamydia-specific IgG antibody, and fibrinogen were assayed in the serum of 159 patients with arterial disease (the arterial group) and 203 patients with heart valve prostheses (the valvular group) and no demonstrable coronary disease. In the arterial group, the Chlamydia pneumoniae antibody was > or = 1:32 for 67.3% (107/159) of the patients, the C-reactive protein was elevated in 41.5% (66/159), and the fibrinogen was elevated in 27.7% (44/159). In the valvular group, the C. pneumoniae antibody was > or = 1:32 for 59.1% (120/203) of the patients; the C-reactive protein was elevated in 34.0% (69/203), and the fibrinogen was elevated in 17.2% (35/203). Of 107 patients in the arterial group with C. pneumoniae titers > or = 1:32, only 26 (24.3%) had elevated fibrinogen (426 +/- 29 mg/dL) and 44 (41.1%) had elevated C-reactive protein (1.06 +/- 0.52 mg/dL). Similarly, of the 120 patients in the valvular group with C. pneumoniae titers > or = 1:32, 17 (14.2%) had elevated fibrinogen (409 +/- 29 mg/dL) and 34 had elevated C-reactive protein (0.99 +/- 1.1 mg/dL). Correlated poorly was C. pneumoniae with C-reactive protein and fibrinogen levels. Only the fibrinogen level could be discriminated between the arterial and the valvular group. These results suggest that no causal association exists between inflammation and C. pneumoniae. A highly significant correlation between C-reactive protein and fibrinogen levels was found.

Chlamydia pneumoniae and atherosclerosis -- what we know and what we don't

The clinical manifestations of atherosclerosis include coronary artery disease (CAD), stroke, abdominal aortic aneurysm and peripheral vascular disease. World-wide, CAD and stroke are the leading causes of death and disability. The recognition of atherosclerosis as an inflammatory disease in its genesis, progression and ultimate clinical manifestations has created an interesting area of vascular research. Apart from those well-known traditional risk factors for atherosclerosis, novel and potentially treatable atherosclerotic risk factors such as homocysteine (an amino acid derived from the metabolism of dietary methionine that induces vascular endothelial dysfunction) and infections have emerged. In fact, the century-old 'infectious' hypothesis of atherosclerosis has implicated a number of micro-organisms that may act as contributing inflammatory stimuli. Although cytomegalovirus, Helicobacter pylori and Chlamydia pneumoniae are the three micro-organisms most extensively studied, this review will focus on C. pneumoniae. Collaborative efforts from many disciplines have resulted in the accumulation of evidence from seroepidemiological, pathological, animal model, immunological and antibiotic intervention studies, linking C. pneumoniae with atherosclerosis. Seroepidemiological observations provide circumstantial evidence, which is weak in most prospective studies. Pathological studies have demonstrated the preferential existence of C. pneumoniae in atherosclerotic plaque tissues, while animal model experiments have shown the induction of atherosclerosis by C. pneumoniae. Finally, immunological processes whereby C. pneumoniae could participate in key atherogenic and atherothrombotic events have also been identified. Although benefits of the secondary prevention of atherosclerosis have been demonstrated in some antibiotic intervention studies, a number of negative studies have also emerged. The results of the ongoing large prospective human antibiotic intervention trials may help to finally establish if there is a causal link between C. pneumoniae infection and atherosclerosis.

In vivo uptake of azithromycin in human coronary plaques

Ten patients with symptomatic coronary artery disease received oral azithromycin for 3 days and underwent directional atherectomy on the third day. Azithromycin was found in all plaque samples with a median concentration of 284 ng/ml (95% confidence interval 163 to 517 ng/ml).

Antibiotics in the prevention and treatment of coronary heart disease

Seroepidemiology, pathology, and animal studies provide evidence for a possible association between Chlamydia pneumoniae infections and atherosclerosis, coronary heart disease, and myocardial infarction. If this association exists, then exposure to certain antibiotics may positively affect the clinical course after an acute ischemic cardiac event (secondary prevention) and affect the risk of developing a first-time myocardial infarction (primary prevention). Preliminary evidence from clinical trials suggests that treatment with new macrolide antibiotics may improve outcome after ischemic events, and evidence from a large case-control analysis indicates that exposure to tetracyclines or quinolones may reduce the risk of developing a first-time myocardial infarction. However, antibiotics for the treatment or prevention of ischemic heart disease must not be recommended yet. This review of published studies briefly summarizes the currently available literature on the effects of antibiotics on the risk of developing coronary heart disease and myocardial infarction.

Inflammation, infection and atherosclerosis: do antibacterials have a role in the therapy of coronary artery disease?

Since the recent publication of 3 studies on the use of antibacterials in patients with coronary artery disease (CAD), there has been a phenomenal interest in the role of infection in the genesis of CAD. It is now generally accepted that inflammation accompanies atherosclerosis from its initiation to the evolution of end-events. Inflammation may occur in response to traditional risk factors, such as hyperlipidaemia, smoking and diabetes mellitus. There is a recent resurgence of the concept that inflammation may have an infectious basis. This concept is based on the identification of microorganisms in the atherosclerotic plaque and seropositivity. The data on eradication of the offending organism with antibiotics and prevention of atherosclerosis-related events have, however, been inconsistent. This may reflect lack of precise understanding of steps leading to atherosclerosis and the evolution of acute ischaemic events. Further work in this area may help identify subsets of patient populations within which infection may play a causative role in the genesis of CAD. Targeted therapy then may be considered logical.

The possible role of infections in acute myocardial infarction

Cardiovascular diseases, particularly coronary heart disease (CHD) and myocardial infarction (MI), are among the leading causes for morbidity and mortality in industrialized countries [2, 77]. During the past decades, various clinical or lifestyle risk factors for myocardial infarction such as hyperlipidemia, hypertension, obesity, lack of physical exercise and smoking have been identified. However, it is also recognized that these well-documented risk factors do not sufficiently account for all new cases of myocardial infarction [77]. Many patients with myocardial infarction have only a borderline risk profile or even lack known risk factors. The question arises: What additional risk factors may play a role in the etiology of atherosclerosis and ischemic heart disease?

Chlamydia pneumoniae, the Heart, and Coronary Artery Disease: Is There a Cause and Effect Relationship?

The possibility that infection with Chlamydia pneumoniae may somehow contribute to the pathogenesis of atherosclerosis continues to be explored by researchers worldwide. A direct cause-and-effect relationship between the bacterium and subsequent development of atherosclerosis has yet to be proved. However, compelling indirect evidence continues to mount in favor of this association. In this article the most recent information on this topic is reviewed. Seroepidemiologic and histopathologic evidence will be highlighted, as well as recent animal models of infection and atherosclerosis. In addition, current studies looking at the association of antichlamydial antibiotic use and risk of adverse cardiovascular outcomes will be detailed.

Chlamydia pneumoniae and coronary heart disease

OBJECTIVE

To review the potential association between Chlamydia pneumoniae (CP) infection and coronary artery disease (CAD), and to describe possible therapeutic interventions.

DATA SOURCES

A MEDLINE search of literature (January 1966-January 1998) pertaining to CP infection associated with heart disease was performed. Additional literature was obtained from review of journals and reference lists of pertinent articles identified through the search.

STUDY SELECTION AND DATA EXTRACTION

All articles involving CP and CAD were considered for possible inclusion in this review. Other selected articles involved possible links between infection and the atherosclerotic process, inflammation and inflammatory mediators in the atherosclerotic process, and isolation of CP from human tissue.

DATA SYNTHESIS

Numerous reports have suggested an association between chronic CP and CAD. CP has been seroepidemiologically linked to CAD. The organism has also been isolated from atherosclerotic lesions. Two reports in humans and one report in animals have shown that macrolide therapy (azithromycin or roxithromycin) may decrease the risk of adverse cardiovascular events.

CONCLUSIONS

Evidence seems to support an association between CP infection and an increased incidence of CAD. Additional and larger seroepidemiologic studies of this association need to be performed to establish a causal relationship between infection and CAD. Determination of the actual role of CP in CAD may decide the role of specific antichlamydial therapy in the management of this condition.

Lack of association between first myocardial infarction and past use of erythromycin, tetracycline, or doxycycline

To evaluate the association of prior treatment with antibiotics active against Chlamydia pneumoniae with the risk for incident myocardial infarction, we conducted a population-based case-control study. We found that use of erythromycin, tetracycline, or doxycycline during the previous 5 years was not associated with risk for first myocardial infarction. These results suggest little or no association between the use of these antibiotics and the risk for first myocardial infarction in the primary prevention setting.