Treatment of Chlamydia pneumoniae infection with roxithromycin and effect on neointima proliferation after coronary stent placement (ISAR-3): a randomised, double-blind, placebo-controlled trial

Semiparametric single-index models for optimal treatment regimens with censored outcomes

There is a growing interest in precision medicine, where a potentially censored survival time is often the most important outcome of interest. To discover optimal treatment regimens for such an outcome, we propose a semiparametric proportional hazards model by incorporating the interaction between treatment and a single index of covariates through an unknown monotone link function. This model is flexible enough to allow non-linear treatment-covariate interactions and yet provides a clinically interpretable linear rule for treatment decision. We propose a sieve maximum likelihood estimation approach, under which the baseline hazard function is estimated nonparametrically and the unknown link function is estimated via monotone quadratic B-splines. We show that the resulting estimators are consistent and asymptotically normal with a covariance matrix that attains the semiparametric efficiency bound. The optimal treatment rule follows naturally as a linear combination of the maximum likelihood estimators of the model parameters. Through extensive simulation studies and an application to an AIDS clinical trial, we demonstrate that the treatment rule derived from the single-index model outperforms the treatment rule under the standard Cox proportional hazards model.

Antibiotics for secondary prevention of coronary heart disease

BACKGROUND

Coronary heart disease is the leading cause of mortality worldwide with approximately 7.4 million deaths each year. People with established coronary heart disease have a high risk of subsequent cardiovascular events including myocardial infarction, stroke, and cardiovascular death. Antibiotics might prevent such outcomes due to their antibacterial, antiinflammatory, and antioxidative effects. However, a randomised clinical trial and several observational studies have suggested that antibiotics may increase the risk of cardiovascular events and mortality. Furthermore, several non-Cochrane Reviews, that are now outdated, have assessed the effects of antibiotics for coronary heart disease and have shown conflicting results. No previous systematic review using Cochrane methodology has assessed the effects of antibiotics for coronary heart disease.

OBJECTIVES

We assessed the benefits and harms of antibiotics compared with placebo or no intervention for the secondary prevention of coronary heart disease.

SEARCH METHODS

We searched CENTRAL, MEDLINE, Embase, LILACS, SCI-EXPANDED, and BIOSIS in December 2019 in order to identify relevant trials. Additionally, we searched TRIP, Google Scholar, and nine trial registries in December 2019. We also contacted 11 pharmaceutical companies and searched the reference lists of included trials, previous systematic reviews, and other types of reviews.

SELECTION CRITERIA

Randomised clinical trials assessing the effects of antibiotics versus placebo or no intervention for secondary prevention of coronary heart disease in adult participants (≥18 years). Trials were included irrespective of setting, blinding, publication status, publication year, language, and reporting of our outcomes.

DATA COLLECTION AND ANALYSIS

Three review authors independently extracted data. Our primary outcomes were all-cause mortality, serious adverse event according to the International Conference on Harmonization - Good Clinical Practice (ICH-GCP), and quality of life. Our secondary outcomes were cardiovascular mortality, myocardial infarction, stroke, and sudden cardiac death. Our primary time point of interest was at maximum follow-up. Additionally, we extracted outcome data at 24±6 months follow-up. We assessed the risks of systematic errors using Cochrane 'Rosk of bias' tool. We calculated risk ratios (RRs) with 95% confidence intervals (CIs) for dichotomous outcomes. We calculated absolute risk reduction (ARR) or increase (ARI) and number needed to treat for an additional beneficial outcome (NNTB) or for an additional harmful outcome (NNTH) if the outcome result showed a beneficial or harmful effect, respectively. The certainty of the body of evidence was assessed by GRADE.

MAIN RESULTS

We included 38 trials randomising a total of 26,638 participants (mean age 61.6 years), with 23/38 trials reporting data on 26,078 participants that could be meta-analysed. Three trials were at low risk of bias and the 35 remaining trials were at high risk of bias. Trials assessing the effects of macrolides (28 trials; 22,059 participants) and quinolones (two trials; 4162 participants) contributed with the vast majority of the data. Meta-analyses at maximum follow-up showed that antibiotics versus placebo or no intervention seemed to increase the risk of all-cause mortality (RR 1.06; 95% CI 0.99 to 1.13; P = 0.07; I2 = 0%; ARI 0.48%; NNTH 208; 25,774 participants; 20 trials; high certainty of evidence), stroke (RR 1.14; 95% CI 1.00 to 1.29; P = 0.04; I2 = 0%; ARI 0.73%; NNTH 138; 14,774 participants; 9 trials; high certainty of evidence), and probably also cardiovascular mortality (RR 1.11; 95% CI 0.98 to 1.25; P = 0.11; I2= 0%; 4674 participants; 2 trials; moderate certainty of evidence). Little to no difference was observed when assessing the risk of myocardial infarction (RR 0.95; 95% CI 0.88 to 1.03; P = 0.23; I2 = 0%; 25,523 participants; 17 trials; high certainty of evidence). No evidence of a difference was observed when assessing sudden cardiac death (RR 1.08; 95% CI 0.90 to 1.31; P = 0.41; I2 = 0%; 4520 participants; 2 trials; moderate certainty of evidence). Meta-analyses at 24±6 months follow-up showed that antibiotics versus placebo or no intervention increased the risk of all-cause mortality (RR 1.25; 95% CI 1.06 to 1.48; P = 0.007; I2 = 0%; ARI 1.26%; NNTH 79 (95% CI 335 to 42); 9517 participants; 6 trials; high certainty of evidence), cardiovascular mortality (RR 1.50; 95% CI 1.17 to 1.91; P = 0.001; I2 = 0%; ARI 1.12%; NNTH 89 (95% CI 261 to 49); 9044 participants; 5 trials; high certainty of evidence), and probably also sudden cardiac death (RR 1.77; 95% CI 1.28 to 2.44; P = 0.0005; I2 = 0%; ARI 1.9%; NNTH 53 (95% CI 145 to 28); 4520 participants; 2 trials; moderate certainty of evidence). No evidence of a difference was observed when assessing the risk of myocardial infarction (RR 0.95; 95% CI 0.82 to 1.11; P = 0.53; I2 = 43%; 9457 participants; 5 trials; moderate certainty of evidence) and stroke (RR 1.17; 95% CI 0.90 to 1.52; P = 0.24; I2 = 0%; 9457 participants; 5 trials; high certainty of evidence). Meta-analyses of trials at low risk of bias differed from the overall analyses when assessing cardiovascular mortality at maximum follow-up. For all other outcomes, meta-analyses of trials at low risk of bias did not differ from the overall analyses. None of the trials specifically assessed serious adverse event according to ICH-GCP. No data were found on quality of life.

AUTHORS' CONCLUSIONS

Our present review indicates that antibiotics (macrolides or quinolones) for secondary prevention of coronary heart disease seem harmful when assessing the risk of all-cause mortality, cardiovascular mortality, and stroke at maximum follow-up and all-cause mortality, cardiovascular mortality, and sudden cardiac death at 24±6 months follow-up. Current evidence does, therefore, not support the clinical use of macrolides and quinolones for the secondary prevention of coronary heart disease. Future trials on the safety of macrolides or quinolones for the secondary prevention in patients with coronary heart disease do not seem ethical. In general, randomised clinical trials assessing the effects of antibiotics, especially macrolides and quinolones, need longer follow-up so that late-occurring adverse events can also be assessed.

Adverse events in people taking macrolide antibiotics versus placebo for any indication

BACKGROUND

Macrolide antibiotics (macrolides) are among the most commonly prescribed antibiotics worldwide and are used for a wide range of infections. However, macrolides also expose people to the risk of adverse events. The current understanding of adverse events is mostly derived from observational studies, which are subject to bias because it is hard to distinguish events caused by antibiotics from events caused by the diseases being treated. Because adverse events are treatment-specific, rather than disease-specific, it is possible to increase the number of adverse events available for analysis by combining randomised controlled trials (RCTs) of the same treatment across different diseases.

OBJECTIVES

To quantify the incidences of reported adverse events in people taking macrolide antibiotics compared to placebo for any indication.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), which includes the Cochrane Acute Respiratory Infections Group Specialised Register (2018, Issue 4); MEDLINE (Ovid, from 1946 to 8 May 2018); Embase (from 2010 to 8 May 2018); CINAHL (from 1981 to 8 May 2018); LILACS (from 1982 to 8 May 2018); and Web of Science (from 1955 to 8 May 2018). We searched clinical trial registries for current and completed trials (9 May 2018) and checked the reference lists of included studies and of previous Cochrane Reviews on macrolides.

SELECTION CRITERIA

We included RCTs that compared a macrolide antibiotic to placebo for any indication. We included trials using any of the four most commonly used macrolide antibiotics: azithromycin, clarithromycin, erythromycin, or roxithromycin. Macrolides could be administered by any route. Concomitant medications were permitted provided they were equally available to both treatment and comparison groups.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted and collected data. We assessed the risk of bias of all included studies and the quality of evidence for each outcome of interest. We analysed specific adverse events, deaths, and subsequent carriage of macrolide-resistant bacteria separately. The study participant was the unit of analysis for each adverse event. Any specific adverse events that occurred in 5% or more of any group were reported. We undertook a meta-analysis when three or more included studies reported a specific adverse event.

MAIN RESULTS

We included 183 studies with a total of 252,886 participants (range 40 to 190,238). The indications for macrolide antibiotics varied greatly, with most studies using macrolides for the treatment or prevention of either acute respiratory tract infections, cardiovascular diseases, chronic respiratory diseases, gastrointestinal conditions, or urogynaecological problems. Most trials were conducted in secondary care settings. Azithromycin and erythromycin were more commonly studied than clarithromycin and roxithromycin.Most studies (89%) reported some adverse events or at least stated that no adverse events were observed.Gastrointestinal adverse events were the most commonly reported type of adverse event. Compared to placebo, macrolides caused more diarrhoea (odds ratio (OR) 1.70, 95% confidence interval (CI) 1.34 to 2.16; low-quality evidence); more abdominal pain (OR 1.66, 95% CI 1.22 to 2.26; low-quality evidence); and more nausea (OR 1.61, 95% CI 1.37 to 1.90; moderate-quality evidence). Vomiting (OR 1.27, 95% CI 1.04 to 1.56; moderate-quality evidence) and gastrointestinal disorders not otherwise specified (NOS) (OR 2.16, 95% CI 1.56 to 3.00; moderate-quality evidence) were also reported more often in participants taking macrolides compared to placebo.The number of additional people (absolute difference in risk) who experienced adverse events from macrolides was: gastrointestinal disorders NOS 85/1000; diarrhoea 72/1000; abdominal pain 62/1000; nausea 47/1000; and vomiting 23/1000.The number needed to treat for an additional harmful outcome (NNTH) ranged from 12 (95% CI 8 to 23) for gastrointestinal disorders NOS to 17 (9 to 47) for abdominal pain; 19 (12 to 33) for diarrhoea; 19 (13 to 30) for nausea; and 45 (22 to 295) for vomiting.There was no clear consistent difference in gastrointestinal adverse events between different types of macrolides or route of administration.Taste disturbances were reported more often by participants taking macrolide antibiotics, although there were wide confidence intervals and moderate heterogeneity (OR 4.95, 95% CI 1.64 to 14.93; I² = 46%; low-quality evidence).Compared with participants taking placebo, those taking macrolides experienced hearing loss more often, however only four studies reported this outcome (OR 1.30, 95% CI 1.00 to 1.70; I² = 0%; low-quality evidence).We did not find any evidence that macrolides caused more cardiac disorders (OR 0.87, 95% CI 0.54 to 1.40; very low-quality evidence); hepatobiliary disorders (OR 1.04, 95% CI 0.27 to 4.09; very low-quality evidence); or changes in liver enzymes (OR 1.56, 95% CI 0.73 to 3.37; very low-quality evidence) compared to placebo.We did not find any evidence that appetite loss, dizziness, headache, respiratory symptoms, blood infections, skin and soft tissue infections, itching, or rashes were reported more often by participants treated with macrolides compared to placebo.Macrolides caused less cough (OR 0.57, 95% CI 0.40 to 0.80; moderate-quality evidence) and fewer respiratory tract infections (OR 0.70, 95% CI 0.62 to 0.80; moderate-quality evidence) compared to placebo, probably because these are not adverse events, but rather characteristics of the indications for the antibiotics. Less fever (OR 0.73, 95% 0.54 to 1.00; moderate-quality evidence) was also reported by participants taking macrolides compared to placebo, although these findings were non-significant.There was no increase in mortality in participants taking macrolides compared with placebo (OR 0.96, 95% 0.87 to 1.06; I² = 11%; low-quality evidence).Only 24 studies (13%) provided useful data on macrolide-resistant bacteria. Macrolide-resistant bacteria were more commonly identified among participants immediately after exposure to the antibiotic. However, differences in resistance thereafter were inconsistent.Pharmaceutical companies supplied the trial medication or funding, or both, for 91 trials.

AUTHORS' CONCLUSIONS

The macrolides as a group clearly increased rates of gastrointestinal adverse events. Most trials made at least some statement about adverse events, such as "none were observed". However, few trials clearly listed adverse events as outcomes, reported on the methods used for eliciting adverse events, or even detailed the numbers of people who experienced adverse events in both the intervention and placebo group. This was especially true for the adverse event of bacterial resistance.

Systematic Review, Meta-analysis, and Network Meta-analysis of the Cardiovascular Safety of Macrolides

Studies reporting an increased risk for cardiac toxicities with macrolide antibiotics have raised concern regarding their cardiovascular safety. We sought to assess the cardiac safety of macrolide antibiotics as a class and of the individual agents by conducting a systematic review and network meta-analysis. Medline, Embase, and the Cochrane Library were searched up to February 2018 for studies reporting on cardiovascular outcomes with macrolides. We followed the PRISMA 2009 guidelines for data selection and extraction. Outcomes were pooled using random-effects models and odds ratios (OR), and 95% confidence intervals (CI) were calculated for arrhythmia, cardiovascular death, and myocardial infarction (MI). A total of 33 studies and data on 22,601,032 subjects were retrieved and included in the current meta-analyses. Macrolide use was not associated with the risk of arrhythmia or cardiovascular mortality. In the primary analysis, macrolide use was associated with a small but statistically significant 15% increase in risk for MI (OR = 1.15 [95% CI, 1.01 to 1.30]). In indirect network meta-analysis, erythromycin and clarithromycin were ranked considerably more likely to be associated with a higher risk for MI and significantly associated with increased risk of MI compared to azithromycin (OR = 1.58 [95% CI, 1.18 to 2.11] and OR = 1.41 [95% CI, 1.11 to 1.81], respectively). Our findings indicate that macrolide antibiotics as a group are associated with a significant risk for MI but not for arrhythmia and cardiovascular mortality. Among the macrolides, erythromycin and clarithromycin were associated with a greater risk of MI. However, it is possible that the association between macrolide use and risk of MI is the result of residual confounding.

Long-Term Risk of Cardiovascular Death With Use of Clarithromycin and Roxithromycin: A Nationwide Cohort Study

Recent studies have raised concern that macrolide antibiotics may be associated with an increased long-term risk of cardiovascular death. We examined the 1-year risk associated with treatment with clarithromycin (n = 187,887) or roxithromycin (n = 698,899) compared with penicillin V (n = 3,473,081), matched 1:4 on propensity score, in a nationwide, registry-based cohort study in Danish outpatients, 1997-2011. Among clarithromycin courses, the rate ratio for cardiovascular death was 1.24 (95% confidence interval (CI): 0.96, 1.59). Among roxithromycin courses, the rate ratio was 0.99 (95% CI: 0.86, 1.16). In analyses by time after treatment start, the rate ratio associated with clarithromycin was 1.66 (95% CI: 0.98, 2.79) during days 0-7. This was attenuated in later time periods (days 8-89, rate ratio = 1.30, 95% CI: 0.88, 1.94; and days 90-364, rate ratio = 0.96, 95% CI: 0.63, 1.47). For roxithromycin, the rate ratios were 0.88 (95% CI: 0.59, 1.32) during days 0-7, 1.17 (95% CI: 0.92, 1.48) during days 8-89, and 0.88 (95% CI: 0.70, 1.10) during days 90-364. We found no increased risk of cardiovascular death in a general outpatient population. With clarithromycin, we observed a transient increased risk during days 0-7 after treatment start, which corresponds to the period of active treatment. This association was absent in later time periods, which is consistent with no long-term toxicity resulting in cardiovascular death.

Chlamydia Pneumoniae Infection in Patients with Acute Coronary Syndrome: A Clinical and Serological 1-Year Follow-Up

The role of Chlamydia pneumoniae infection in pathogenesis and prognostic stratification of patients with acute coronary syndromes is still unclear. However, a limitation of many studies is the evaluation of the long-term prognostic role of a sample obtained during the acute phase, whereas the assessment of the temporal trend of antibody titers could be more useful. One-hundred and fourteen consecutive patients with acute coronary syndromes (71 with acute myocardial infarction and 43 with unstable angina) were studied. Blood samples were obtained immediately after hospital admission and 1, 3, 6 and 12 months after the acute event. The microimmunofluorescence test was used to detect C. pneumoniae specific antibodies. The incidence of new coronary events (death, myocardial infarction, recurrent angina) was recorded during the 1-year follow-up period. No significant difference was found between patients with (n = 35) or without (n = 79) new coronary events (N.C.E.) regarding baseline and serial values of C. pneumoniae antibodies. The rate of high titers at any time of follow-up was also similar in the two groups: IgG ≥1:512 were present in 52%, 64%, 55% and 32% of N.C.E.+ patients, and in 48%, 54%, 52% and 36% of N.C.E.- patients at 1, 3, 6 and 12 months respectively; IgA ≥ 1:256 were present in 26%, 23%, 30% and 23% of N.C.E.+ patients and in 20%, 30%, 25% and 19% of N.C.E.- patients at 1, 3, 6 and 12 months respectively. Our data indicate that elevated titers of C. pneumoniae antibodies, even with a serial 1-year evaluation, are not a predictor of future coronary events in patients with acute myocardial infarction or unstable angina.

Clinical significance of Helicobacter pylori infection in patients with acute coronary syndromes: an overview of current evidence

Although Helicobacter pylori (Hp) primarily colonizes gastric mucosa, it can occasionally inhabit in atherosclerotic plaques. Both forms of Hp infection may be involved in the pathogenesis of atherosclerosis via activation of a systemic or local inflammatory host reaction and induction of plaque progression and/or instability, possibly leading to coronary syndromes. The association between Hp infection and cardiovascular endpoint prevalence remains uncertain; however, it has been reported in many epidemiological investigations and may be reasonably explained by pathophysiological mechanisms. Besides the inflammatory pathway, Hp infection may trigger acute coronary syndromes by enhanced platelet reactivity and increased risk of gastrointestinal bleeding (type 2 myocardial infarction). The former seems to be predominantly related to the stimulatory effect of Hp infection on von Willebrand factor-binding and P-selectin activation, and the latter results from cytotoxic bacteria properties and aggravation of digestive tract injury related to aspirin or dual antiplatelet therapy. Despite these premises, the role of Hp infection in cardiovascular syndromes should still be recognized as controversial and requiring randomized, controlled trials to evaluate the outcome of Hp eradication in both cardiac and gastroenterological endpoints. Such need is also justified by potential bias of previous studies resulting from (1) using different diagnostic methods for identification of Hp infection, since only a small number of studies required confirmation of active Hp infection; and from (2) common lack of adjustment for important confounders such as socioeconomic status, smoking and effectiveness of eradication therapy, as well as the genetic characteristics of both the host and the bacterium.

Chlamydophila pneumoniae infection and cardiovascular disease

Atherosclerosis is a multifactorial vascular inflammatory process; however, the inciting cause for inflammation remains unclear. Two decades ago, Chlamydophila pneumoniae (formerly Chlamydia pneumoniae) infection was proposed as a putative etiologic agent. We performed a PubMed search using the keywords Chlamydia and atherosclerosis in a Boolean query to identify published studies on C. pneumoniae and its role in atherogenesis, and to understand research interest in this topic. We found 1,652 published articles on this topic between 1991 and 2011. We analyzed relevant published studies and found various serological, molecular, and animal modeling studies in the early period. Encouraged by positive results from these studies, more than a dozen antibiotic clinical-trials were subsequently conducted, which did not find clinical benefits of anti-Chlamydophila drug therapy. While many researchers believe that the organism is still important, negative clinical trials had a similar impact on overall research interest. With many novel mechanisms identified for atherogenesis, there is a need for newer paradigms in Chlamydophila-atherosclerosis research.

Atherosclerosis and infection: is the jury still not in?

Atherosclerosis is a chronic inflammatory process accounting for increased cardiovascular and cerebrovascular morbidity and mortality. A wealth of recent data has implicated several infectious agents, mainly Chlamydophila pneumoniae, Helicobacter pylori, CMV and periodontal pathogens, in atherosclerosis. Thus, we sought to comprehensively review the available data on the topic, exploring in particular the pathogenetic mechanisms, and discuss anticipated future directions.

Influenza vaccination and cardiovascular morbidity and mortality: analysis of 292,383 patients

Studies have documented an association between influenza vaccination and risk reduction in myocardial infarction, all-cause mortality, and major adverse cardiac events. This meta-analysis pooled data from 5 trials with a total of 292 383 patients. Influenza vaccination was found to be associated with significant reductions in myocardial infarction, all-cause mortality, and major adverse cardiac events. The risk reduction afforded by vaccination and the lack of major adverse events related to the influenza vaccination makes it particularly important to vaccinate those with a known cardiovascular disease or those at high risk of developing cardiovascular disease.

Influenza vaccination reduces cardiovascular events in patients with acute coronary syndrome

AIMS

Influenza infection has been shown to accentuate the progression of atherosclerosis and precipitate the occurrence of acute coronary syndrome (ACS). However, the protective effects of the influenza vaccine on cardiovascular events are still inconclusive.

METHODS AND RESULTS

The study was a prospective randomized open with blinded endpoint (PROBE) study. The 439 patients who had been admitted due to ACS within 8 weeks were enrolled and randomly allocated to receive inactivated influenza vaccine in the vaccine group and no treatment in the control group. All patients were treated with the standard therapy including revascularization according to primary cardiologists. The primary endpoint, which was the combined major cardiovascular events, including death, hospitalization from ACS, hospitalization from heart failure, and hospitalization from stroke, occurred less frequently in the vaccine group than the control group [9.5 vs. 19.3%, unadjusted HR 0.70 (0.57-0.86), P = 0.004]. There was no significant difference in the incidence of cardiovascular death between the vaccine and control groups [2.3 vs. 5.5%, unadjusted HR 0.39 (0.14-1.12), P = 0.088].

CONCLUSION

The influenza vaccine reduced major cardiovascular events in patients with ACS. Therefore, it should be encouraged as a secondary prevention in this group of patients.

Chlamydophila pneumoniae infection in patients undergoing carotid artery stent

Although several reports have correlated Chlamydophila pneumoniae (CP) infection with carotid endarterectomy and coronary stent, no data have been reported on the potential relationship between this pathogen and carotid artery stenting (CAS). Hence, we evaluated 47 subjects, 27 symptomatic and 20 asymptomatic, before CAS intervention and during the follow up, for the presence of CP DNA and anti-CP antibodies, including chlamydial HSP60 (Cp-HSP60). Before stent placement, CP DNA was detected exclusively in symptomatic patients, all of whom were also positive for CP IgG and IgA and 85.7 percent of them also had CP-HSP60 antibodies. At the follow-up, all CP DNA positive and 11 out of the 13 symptomatic patients with Cp-HSP60 antibodies became negatives. In contrast, no change was observed for CP- IgA antibodies. Despite the small number of patients, the present study advocates an important role of CP infection in symptomatic patients with carotid artery disease. Our findings also suggest that stent placement and/or therapy might have a role in favouring resolution of inflammation, though not affecting persistence of CP infection.

Azithromycin does not prevent six-month myointimal proliferation but attenuates the transient systemic inflammation occurring after coronary stenting

OBJECTIVES

Stent implantation produces a systemic increase of inflammatory markers that correlates with Chlamydophila pneumoniae infection in atherosclerotic plaque. We performed a clinical intervention study to investigate the effect of antibiotic treatment on 6-month follow-up angiographic minimal luminal diameter after stenting.

METHODS

Ninety patients were randomly assigned to oral azithromycin or placebo in a double-blinded and randomized fashion. Medication was initiated 2 weeks before a pre-scheduled stenting procedure and maintained 12 weeks thereafter. Angiographic outcomes were evaluated by a six-month follow-up angiography and laboratorial parameters were accessed by blood sampling 2 weeks before stenting, within the first 24 h after procedure and additional samples after four weeks and 6 months.

RESULTS

Minimal luminal diameter (1.76 +/- 0.56 mm Vs. 1.70 +/- 0.86 mm; P = 0.7), restenosis rate, diameter stenosis, late loss, and binary restenosis rates were comparable in placebo and azithromycin group in the 6 months follow-up. Serum levels of C-reactive protein presented a three fold significant increase in the control group one day after stenting but did not change in the azithromycin group (8.5 [3.0;16.4] Vs. 2.9 [1.7;6.6]-median [25;75 percentile] P < 0.01).

CONCLUSIONS

Azithromycin does not improve late angiographic outcomes but attenuates the elevation of C-reactive protein levels after stenting, indicating an anti-inflammatory effect.

A meta-analysis of antibiotic use for the secondary prevention of cardiovascular diseases

BACKGROUND

A number of clinical trials have examined whether antibiotics decrease the incidence of adverse events in patients with cardiovascular diseases. However, results have occasionally been conflicting, and a meta-analysis may provide additional clarification.

OBJECTIVE

To address whether antibiotic use can reduce the risk of future cardiac events among patients with established cardiovascular diseases.

METHODS

PubMed and the Cochrane Central Register of Controlled Trials were searched using the key words "antibiotic" and "cardiovascular diseases". Only randomized, placebo-controlled trials of patients with established cardiovascular disease and reporting cardiovascular outcomes were included. A random effects model was used and a fixed model was applied for sensitivity analysis.

RESULTS

A total of 393 papers published between January 1, 1994, and April 31, 2006, were initially identified. Thirteen trials (12,491 patients in the treatment group and 12,518 patients in the control group) were retained and included in the present meta-analysis. The pooled RR for the composite event end point, including death, myocardial infarction admission and unplanned revascularization procedures, was 0.96 (95% CI 0.90 to 1.04). No associations were seen for the individual outcomes of mortality (RR 1.07, 95% CI 0.96 to 1.19) or myocardial infarction/unstable angina (RR 0.96, 95% CI 0.85 to 1.07). Subgroup analyses based on patient populations (stable or unstable), type of antibiotics, or restricted to those with immunoglobulin G Chlamydia pneumoniae antibodies were also negative for a beneficial treatment effect. Similar results were found using a fixed effects model.

CONCLUSIONS

The meta-analysis did not provide evidence of an association between antibiotic use and the secondary prevention of cardiac events. Further research in this area does not appear to be promising.

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.

Rifalazil and Other Benzoxazinorifamycins in the Treatment of Chlamydia-Based Persistent Infections

Rifalazil is a benzoxazinorifamycin which inhibits bacterial DNA-dependent RNA polymerase. The benzoxazine ring endows benzoxazinorifamycins with unique physical and chemical characteristics which favor the use of rifalazil and derivatives in treating diseases caused by the obligate intracellular pathogens of the genus chlamydia. Minimal inhibitory concentrations of benzoxazinorifamycins against chlamydia are in the pg/mL range. These compounds have potential as monotherapeutic agents to treat chlamydia-associated disease because they retain activity against chlamydia strains resistant to currently approved rifamycins such as rifampin. A pivotal clinical trial with rifalazil has been initiated for the treatment of peripheral arterial disease. The rationale for this innovative use of rifalazil, including the association of C. pneumoniae in atherosclerotic plaque formation, as well as rifalazil's potency and efficacy against chlamydia in both preclinical and clinical studies, is discussed. Other benzoxazino derivatives may have utility as stand-alone topical antibacterials or combination antibacterials to treat serious Gram-positive infections. None of the benzoxazinorifamycins examined to date induce the cytochrome P450 3A4 enzyme. This is in contrast to currently approved rifamycins which are strong inducers of P450 enzymes, resulting in drug-drug interactions that limit the clinical utility of this drug class.

No prognostic significance of chronic infection with Chlamydia pneumoniae in acute coronary syndromes: insights from the Global Utilization of Strategies to Open Occluded Arteries IV Acute Coronary Syndromes trial

BACKGROUND

Although relationships between chronic Chlamydia pneumoniae (Cpn) infection and the risk of coronary events in stable coronary artery disease patients have been reported, a similar link in acute coronary syndrome (ACS) patients has not been consistently observed.

METHODS

In a nested case-control substudy of the Global Utilization of Strategies to Open Occluded Arteries IV Acute Coronary Syndromes trial, 295 cases (30-day death/myocardial infarction [MI]) were matched by age, sex, baseline creatine kinase-myocardial kinase, and smoking status with 295 control subjects. To test the hypothesis on 1-year mortality, another subset (n = 276) was drawn from the 590-patient cohort; 138 patients who died at 1 year plus the matching controls who survived at 1 year. We measured Cpn IgG and IgA antibody titers in baseline serum with microimmunofluorescence. Conditional logistic regression was used to quantify the prognostic relevance seropositivity (IgG > or = 1:32; IgA > or = 1:16) and elevated titer levels.

RESULTS

The prevalence of Cpn IgG and IgA was similar between cases and controls (30-day death/MI: IgG, 80% vs 85%, P = .126; IgA, 45% vs 37%, P = .079), and were not statistically significant predictors of 30-day death/MI after baseline adjustment. Likewise, the 1-year death cohort had comparable proportions of Cpn IgG and IgA among cases and controls (86% vs 91% [P = .265] and 49% vs 43% [P = .334], respectively), and did not add prognostic value.

CONCLUSIONS

These findings are in concert with study results suggesting that chronic Cpn infection is not associated with 30-day death/MI or 1-year mortality in non-ST elevation ACS.

Can long-term antibiotic treatment prevent progression of peripheral arterial occlusive disease? A large, randomized, double-blinded, placebo-controlled trial

PURPOSE

The purpose was to investigate in a large, randomized, double-blinded, placebo-controlled trial, whether antibiotic treatment can prevent progression of peripheral arterial disease (PAD).

MATERIAL AND METHODS

Five hundred and seven patients were included; all patients had an established diagnosis of PAD. Their mean age was 66 years (36-85), and 59% were males. Patients were randomized to Roxithromycin 300 mg daily for 28 days. Baseline investigations were ankle blood pressure, ankle-brachial blood pressure index (ABPI), walking distance, C. pneumoniae serology, cholesterol and medical history. Follow-up was performed every 6 months. Primary events were defined as death, peripheral revascularization and major lower limb amputation. Secondary events were thrombosis, stroke, transient cerebral ischaemic attack and myocardial infarction. Change in ABPI was also investigated. Data were analyzed mainly by Cox regression and linear regression.

RESULTS

Included patients with PAD were randomized. Two patients withdrew. Of the remaining, 248 received roxithromycin and 257 placebo. In the treatment group 55% were seropositive and 53% in the placebo group. Mean follow-up was 2.1 years (range 0.06-5.1 years). In the placebo group, 26 died and 80 primary events occurred in total. In the treatment group, 28 died and 74 primary events were observed. The hazard ratio of death was 1.13 (95% CI: 0.68; 1.90), and of primary events 0.92 (95% CI: 0.67; 1.26). Also on secondary events and ABPI changes, no significant differences were found.

CONCLUSION

Long-term treatment with roxithromycin is ineffective in preventing death, amputation, peripheral revascularization, myocardial infarction, stroke, transient cerebral ischaemic attack, thrombosis and decline in ABPI in patients with an established diagnosis of PAD.

Macrolide use and the risk of vascular disease in HIV-infected men in the Multicenter AIDS Cohort Study

Background: There has been increasing concern that HIV-infected individuals may be more at risk for cardiovascular events in the highly-active antiretroviral therapy (HAART) era. This study examined the risk of thromboembolic events in HIV-infected and non-infected individuals and the effect of macrolide prophylaxis on those outcomes. Methods: A subcohort analysis was undertaken using data collected in the Multicenter AIDS Cohort Study to examine the relative risk of vascular events (myocardial infarction, unstable angina and ischaemic stroke). Cox proportional hazard model using age as the time scale with time varying cofactors obtained at each semi-annual visit were used to assess the independent effect of macrolide use. Results: Controlling for other significant effects including race and smoking, HIV-infection was not independently associated with vascular events. Increased risk was observed among those who used HAART (relative hazard 1.09, 95% confidence intervals 1.00–1.19 in multivariate model), antihypertensive treatment (1.81 [1.26–2.60]), lipid-lowering medication (1.65 [1.12–2.42]), and antibiotics (1.72 [1.25–2.36]). The protective association of macrolide use for a vascular event in the HAART era was also significant (0.10 [0.01–0.75]). Conclusions: Traditional risk factors are important in the pathogenesis of vascular events in HIV-infected individuals. Macrolide antibiotics may have a protective effect in the HIV-infected individuals in the HAART era.

Development potential of rifalazil and other benzoxazinorifamycins

Rifalazil and other benzoxazinorifamycins (new chemical entities [NCEs]) are rifamycins that contain a distinct planar benzoxazine ring. Rifalazil has excellent antibacterial activity, high intracellular levels and high tissue penetration, which are attributes that favour its use in treating diseases caused by the obligate intracellular pathogens of the genus Chlamydia. Recent studies have shown that rifalazil has efficacy in the treatment of human sexually transmitted disease caused by Chlamydia trachomatis. The extraordinary potency of rifalazil and other NCEs, such as ABI-0043, extends to the related microorganism, C. pneumoniae, a respiratory pathogen that can disseminate and persist chronically in the vasculature, resulting in increased plaque formation in animal studies. A pivotal clinical trial with rifalazil has been initiated for the treatment of peripheral arterial disease. Other opportunities include gastric ulcer disease caused by Helicobacter pylori and antibiotic-associated colitis caused by infection with Clostridium difficile in the colon. The NCEs could prove to be valuable as follow-on compounds in these indications, as rifampin replacements in antibacterial combination therapy or as stand-alone topical antibacterials (e.g., to treat acne). Neither rifalazil nor NCEs appear to induce the cytochrome P450 3A4, an attribute of rifampin that can result in adverse events due to drug-drug interactions.

Isolation of Chlamydophila pneumoniae from atheromas of the carotid artery and their antibiotics susceptibility profile

BACKGROUND

Atherosclerosis is pathogenically similar to a chronic inflammatory response. Peripheral arterial disease (PAD) is a common manifestation of atherosclerosis. Chlamydophila pneumoniae has been suggested to play a role in the origin of PAD.

OBJECTIVE

To determine whether C. pneumoniae is present in atherosclerosis lesions of the carotid artery wall in patients with PAD through several diagnostic methods and to characterize C. pneumoniae susceptibility profiles.

METHODS

The presence of C. pneumoniae in 9 tissue samples from atherosclerotic lesions obtained by carotid endarterectomy was investigated by 3 methods. Karnofsky-fixed specimens were examined by transmission electron microscopy (TEM), isolation of C. pneumoniae was attempted in LLCMK2 cell structure (ICC), and the presence of chlamydial DNA was investigated by polymerase chain reaction (PCR). The in vitro activities of azithromycin, roxithromycin and penicillin were tested in 4 isolations and the reference strain of C. pneumoniae (AR39).

RESULTS

C. pneumoniae was detected in atherosclerotic plaques from 4 patients with PAD. The pathogen was identified by TEM, PCR and ICC. We report data of the in vitro susceptibility of 4 strains. These strains did not differ from respiratory AR39 strain in their susceptibility patterns to azithromycin, roxithromycin and penicillin.

CONCLUSIONS

C. pneumoniae is frequently found in the advanced carotid atherosclerotic lesions of patients undergoing endarterectomy. Although these findings do not establish causality in carotid artery atherosclerosis, they should stimulate investigation of the possible causal or pathogenic role of C. pneumoniae. Notably, the profiles of antibiotic susceptibility of C. pneumoniae isolated from 4 of the patients did not differ from those of the reference strain.

Antibiotics active against Chlamydia do not reduce the risk of myocardial infarction

OBJECTIVE

There is evidence that Chlamydia pneumoniae (CP) is involved in the aetiology of myocardial infarction (MI). Randomised trials do not support a beneficial effect of antibiotics in secondary prevention of MI, but the evidence for an effect on primary prevention is conflicting. We investigated if past use of antibiotics active against CP is associated with a decreased risk of developing MI.

METHODS

We conducted a population-based case-control study of 4166 patients hospitalised due to MI from 1 January 1994 to 1 September 1999 in the County of Funen, Denmark. Controls (n=16,664) were a random sample of inhabitants, matched for age and sex. Confounders controlled for in the analysis were gender, age, obstructive pulmonary disease, diabetes, previous MI and known atherosclerotic antecedents. Previous use of antibiotics active against CP (macrolides, tetracyclines and quinolones) and of antibiotics not active against CP (penicillins) was analysed among the cases and controls.

RESULTS

The risk of MI was not associated with previous exposure to macrolides (OR: 1.0; CI: 0.9-1.1), tetracyclines (OR: 1.0; CI: 0.9-1.2) or quinolones (OR: 1.0; CI: 0.9-1.2) or combinations of the three drugs (OR: 1.0; CI: 0.9-1.1). There was no sign of a protective effect in subgroups defined by high cumulative doses of antibiotics, various time-windows of exposure, risk factors of MI or other co-morbidity. OR was 1.1 (0.9-1.3) in persons with no atherosclerotic antecedents.

CONCLUSION

The study does not support the hypothesis of a decreased risk of MI in patients exposed to antibiotics active against CP.

Association of HLA-DRB3*0202 and serum IgG antibodies to Chlamydia pneumoniae with essential hypertension in a highly homogeneous population from Majorca (Balearic Islands, Spain)

Separate studies investigating the relationship of essential hypertension (EH) with the HLA system and with Chlamydia pneumoniae (C. pneumoniae) infection have given conflicting results. Our aim was to clarify these relationships and determine whether the HLA system and C. pneumoniae infection interact with respect to the risk for EH. An association study (110 essential hypertensives and 107 controls) was conducted in a highly homogeneous population in the Balearic Island of Majorca (Spain). Molecular typing of HLA-B and HLA-DRB and quantification of serum levels of IgG antibodies to C. pneumoniae (sIgGa-Cp) were determined. Student's t-test, chi(2)-statistics, logistic regression analysis, and general linear model ANOVA were used for statistical analysis. The results showed that EH was related with HLA-DRB3*0202 in the whole study population, and with levels of sIgGa-Cp>63.5 BU/ml in the group of individuals with sIgGa-Cp>30 BU/ml (OR (95% CI) adjusted for obesity, familial history of EH and diabetes=2.06 (1.07-3.97), P=0.03, and =4.60 (1.06-19.90), P=0.04, respectively). The association between EH and sIgGa-Cp was observed in the DRB3*0202(+) individuals, but not in the DRB3*0202(-) subgroup (OR (95% CI)=11.14 (1.92-64.54), P=0.004, and =0.98 (0.22-4.43), P=0.64, respectively (P of the Mantel-Haenszel test for homogeneity of OR=0.06)). In our population, EH was positively associated with HLA-DRB3*0202 and with high levels of sIgGa-Cp. Moreover, a significant interaction of DRB3*0202 on the effect of sIgGa-Cp was observed, as the association of EH with these antibodies depended on the presence of DRB*0202.

A randomized trial in patients undergoing percutaneous coronary angioplasty: roxithromycin does not reduce clinical restenosis but angioplasty increases antibody concentrations against Chlamydia pneumoniae

BACKGROUND

Elevated antibodies against Chlamydia pneumoniae have been associated with coronary artery disease. In patients undergoing percutaneous coronary angioplasty, we therefore investigated the effect of roxithromycin on symptomatic restenosis and determined antichlamydial antibodies as well as inflammatory and immunological parameters.

METHODS

A total of 327 patients undergoing coronary angioplasty were randomized to roxithromycin or placebo and followed-up for 1 year. Antibodies were determined by microimmunofluorescence and enzyme-linked immunosorbent assay; C-reactive protein, interleukin-10, tumor necrosis factor-alpha (TNF-alpha), and eotaxin were determined by enzyme-linked immunosorbent assay.

RESULTS

Although the frequency of restenosis was not affected by roxithromycin (25 restenoses vs 32 in the control group), antichlamydial antibodies increased during follow-up (anti-CP IgG +12 +/- 2%, P < .001). Concentrations of TNF-alpha and eotaxin increased as well (TNF-alpha +9 +/- 1% and eotaxin +10 +/- 2%) and correlated with antichlamydial antibody concentrations (TNF-alpha, r = 0.23, P = .02; eotaxin, r = 0.32, P = .002).

CONCLUSIONS

Treatment with roxithromycin was not associated with a reduction of symptomatic restenoses. During follow-up, a marked increase in antichlamydial antibodies, TNF-alpha, and eotaxin was observed, suggesting that angioplasty-induced plaque rupture induces a specific immunological response without activation of inflammatory mechanisms as represented by C-reactive protein. Whether this mechanism occurs in all plaque ruptures remains to be determined.

Chlamydia pneumoniae and atherosclerosis: from Koch postulates to clinical trials

Atherosclerosis is increasingly viewed as an inflammatory process. A number of infectious agents have been implicated in the pathogenesis of coronary artery disease. Chlamydia pneumoniae has been the most popular and well-studied of these pathogens. It is difficult to prove a causal relationship which requires the fulfillment of Koch's postulates, first developed in the late 1800s, to establish an infectious agent as the cause of a disease process. This paper reviews the evidence for and against Chlamydia pneumoniae infection as a contributing factor to atherosclerosis disease. It examines seroepidemiologic and histopathologic studies as well as animal models using Koch's postulates and then provides an analysis of current clinical trial data.

Roxithromycin is an inhibitor of human coronary artery smooth muscle cells proliferation: a potential ability to prevent coronary heart disease

Roxithromycin (RXM), a macrolide antibiotic, is used in clinical trials to address secondary prevention of coronary heart disease. However, the effects of RXM on human coronary artery smooth muscle cells (CASMC) proliferation remain unclear. Human CASMC were stimulated with growth medium containing 5% fetal bovine serum and growth factors. RXM at 1 or 10 microg/ml, which are relevant to the therapeutic plasma levels, significantly suppressed mitogen-induced CASMC proliferation, assessed by WST-1 assay and cell counting. Flow cytometry analysis demonstrated that RXM suppressed mitogen-induced G1 to S progression on cell cycle. Western blot showed that RXM inhibited phosphorylation of retinoblastoma gene products, reduced protein levels of cyclin D1 and A, and restored downregulation of cyclin-dependent kinase (CDK) inhibitor p27kip1. The activities of CDK4 and CDK2 were suppressed by RXM without affecting their protein levels. When transfected with both IkappaB kinase alpha and beta constructs as nuclear factor-kappa B (NF-kappaB) activator, CASMC entered S phase at 24 h, and RXM inhibited it. Electrophoretic mobility shift assay and immunostaining of NF-kappaB p65 demonstrated that RXM inhibited mitogen-induced NF-kappaB activation. These results indicate that RXM is an inhibitor of human CASMC proliferation through modulating cell cycle regulatory proteins and inhibiting NF-kappaB signaling pathway.

Secondary prevention of atherosclerosis through chlamydia pneumoniae eradication (SPACE Trial): a randomised clinical trial in patients with peripheral arterial disease

BACKGROUND

Sero-epidemiological and experimental studies suggest that Chlamydia pneumoniae infections play an important role in the development of atherosclerosis. Clinical trials have shown contradictory results regarding the efficacy of antibiotics to prevent atherosclerosis-related complications in patients with coronary artery disease. Our aim was to study the effect of a short course of azithromycin on the incidence of cardiovascular events and peripheral vascular function in patients with stable peripheral arterial disease (PAD).

PATIENTS AND METHODS

Five hundred and nine PAD-patients were randomised to receive either a 3-day course of azithromycin (500 mg daily) or placebo, with 2 years of follow-up. C. pneumoniae serology was determined at baseline. Clinical endpoints were death, coronary events (myocardial infarction, unstable angina, and/or coronary revascularization procedures), cerebral events (stroke, TIA, and/or carotid endarterectomy) and peripheral arterial complications (increased PAD-symptoms with decreased ankle-brachial index (ABPI, 0.1-point decrease after 12 months), and/or peripheral revascularization procedures).

RESULTS

Five hundred and nine patients (160 women) with an atherosclerotic risk factor profile were randomised, 257 patients to azithromycin and 252 to placebo. Four hundred and forty nine patients (88%) had intermittent claudication and 60 (12%) had critical limb ischemia. By 24-month follow up, 182 patients (36%) developed 252 complications (45 deaths, 34 coronary events, 34 cerebral events and 139 peripheral arterial complications). C. pneumoniae IgA-titres were associated with the development of cardiovascular events. Nevertheless, the number of complications (131 in the azithromycin group vs. 121 in the placebo group) and the number of patients that developed complications (98 (38%) in the azithromycin vs. 84 (33%) in the placebo group) was comparable in both treatment groups. Life table analysis showed no effect of azithromycin on survival or ABPI.

CONCLUSION

A short-term course of azithromycin offers no benefits for survival or ankle pressure in PAD-patients.

Antibiotic treatment of Chlamydia pneumoniae after acute coronary syndrome

BACKGROUND

Chlamydia pneumoniae has been found within atherosclerotic plaques, and elevated titers of antibody to this organism have been linked to a higher risk of coronary events. Pilot studies have suggested that antibiotic treatment may reduce the risk of cardiovascular events.

METHODS

We enrolled 4162 patients who had been hospitalized for an acute coronary syndrome within the preceding 10 days and evaluated the efficacy of long-term treatment with gatifloxacin, a bactericidal antibiotic known to be effective against C. pneumoniae, in a double-blind, randomized, placebo-controlled trial. Subjects received 400 mg of gatifloxacin daily during an initial 2-week course of therapy that began 2 weeks after randomization, followed by a 10-day course every month for the duration of the trial (mean duration, 2 years), or placebo. The primary end point was a composite of death from all causes, myocardial infarction, documented unstable angina requiring rehospitalization, revascularization (performed at least 30 days after randomization), and stroke.

RESULTS

A Kaplan-Meier analysis revealed that the rates of primary-end-point events at two years were 23.7 percent in the gatifloxacin group and 25.1 percent in the placebo group (hazard ratio, 0.95; 95 percent confidence interval, 0.84 to 1.08; P=0.41). No benefit was seen in any of the prespecified secondary end points or in any of the prespecified subgroups, including patients with elevated titers to C. pneumoniae or C-reactive protein.

CONCLUSIONS

Despite long-term treatment with a bactericidal antibiotic effective against C. pneumoniae, no reduction in the rate of cardiovascular events was observed.

Update of antibiotic trials for secondary prevention of coronary heart disease

The possibility that infection is a stimulus for the vascular inflammation that promotes atherogenesis has spawned clinical trials of antibiotics. These have focused primarily on Chlamydia pneumoniae as a potential atherogenic agent. In contrast to pilot studies, recent large trials, capped by the Azithromycin and Coronary Events Study and PRavastatin Or AtorVastatin Evaluation and Infection Therapy mega trials, indicate that standard antibiotics (e.g., azithromycin and gatifloxacin) are ineffective for secondary cardiovascular prevention. Despite this, observations continue to mount that infection can be a stimulus for atherothrombosis. Thus, one should rethink, revise and reformulate hypotheses, and research strategies, including novel antibiotics and treatment at earlier stages of disease, rather than discard infection prematurely as a potential etiologic factor.

Progression of peripheral arterial occlusive disease is associated with Chlamydia pneumoniae seropositivity and can be inhibited by antibiotic treatment

A possible influence of Chlamydia pneumoniae seropositivity on the clinical course of peripheral arterial occlusive disease (PAOD) has not been investigated previously. Though roxithromycin therapy was found to inhibit progression of PAOD, the nature of this effect (antibiotic or anti-inflammatory) has remained elusive. The course of PAOD was prospectively assessed in elderly men during 4 years, comparing 51 C. pneumoniae seropositive (IgG>/=1:128) with 46 seronegative patients (IgG<1:64 and IgA<1:32). Twenty of the seropositive patients were treated with roxithromycin (400 mg daily) for 4 weeks. Limitation of the walking distance to 200 m or less was observed in 55% of the seropositive untreated patients as compared to 30% of both, seronegative and macrolide-treated patients. The number of invasive revascularizations per patient was 1.7 in the seropositive untreated group as compared to 0.5 in the seronegative and the macrolide-treated group. Considering possible confounding variables, such as classical vascular risk factors, ordinal regression analyses showed a significant association of C. pneumoniae seropositivity with limitation of the walking distance (p=0.027) and need for invasive revascularization (p=0.037). The effect of macrolide treatment on these outcome measures was marked (p<0.001 and p=0.040, respectively) during 2.7 years but decreased in the second part of the observation period. This study provides good evidence that C. pneumoniae are involved in the progression of PAOD and that antibiotic treatment directed against C. pneumoniae is effective in inhibiting this process.

Acute coronary syndrome and chronic infection in the Cork coronary care case-control study

OBJECTIVE

To examine the association between chronic infection and cumulative burden of infection and acute coronary syndrome.

DESIGN

The 5C (Cork coronary care case-control) study was a community based case-control study. Patients and controls underwent a standard physical examination and had blood samples taken for serological analysis for Helicobacter pylori (IgG), Chlamydia pneumoniae (IgA, IgM, and IgG), cytomegalovirus (IgG), and herpes simplex virus types 1 and 2 (IgG).

SETTING

Patients were recruited from four hospitals in Cork City and Mallow Town. Controls, individually matched on age and sex, were selected by incident density sampling from the same general practices as the referent case.

MAIN OUTCOME MEASURES

Age and sex adjusted and fully adjusted odds ratios for acute coronary syndrome by seropositivity and by increasing number of infections.

RESULTS

Cases and controls did not differ significantly in seropositivity to C pneumoniae, cytomegalovirus, herpes simplex viruses, and H pylori. In unconditional logistic regression analysis adjusted for age, sex, waist to hip ratio, smoking, physical activity, alcohol consumption, and social class there was no evidence of an increasing risk for acute coronary syndrome with increasing burden of infection.

CONCLUSIONS

The findings do not support an association between specific infectious agents and acute coronary syndrome and do not provide evidence of a burden of infection effect.

Treating individuals 2. Subgroup analysis in randomised controlled trials: importance, indications, and interpretation

Large pragmatic trials provide the most reliable data about the effects of treatments, but should be designed, analysed, and reported to enable the most effective use of treatments in routine practice. Subgroup analyses are important if there are potentially large differences between groups in the risk of a poor outcome with or without treatment, if there is potential heterogeneity of treatment effect in relation to pathophysiology, if there are practical questions about when to treat, or if there are doubts about benefit in specific groups, such as elderly people, which are leading to potentially inappropriate undertreatment. Analyses must be predefined, carefully justified, and limited to a few clinically important questions, and post-hoc observations should be treated with scepticism irrespective of their statistical significance. If important subgroup effects are anticipated, trials should either be powered to detect them reliably or pooled analyses of several trials should be undertaken. Formal rules for the planning, analysis, and reporting of subgroup analyses are proposed.

Treatment with clarithromycin prior to coronary artery bypass graft surgery does not prevent subsequent cardiac events

BACKGROUND

Recently, it has been suggested that Chlamydia pneumoniae possibly plays a possible role in the pathogenesis of atherosclerosis. We investigated whether treatment with clarithromycin prior to coronary artery bypass graft (CABG) surgery would prevent subsequent cardiovascular events and mortality.

METHODS

Patients who were scheduled for CABG surgery were randomly assigned to receive either clarithromycin or placebo until the day of surgery in a double-blind trial. During the 2 years of follow-up, mortality and cardiovascular events were assessed.

RESULTS

Follow-up at 2 years was achieved for 473 patients. The mean duration of treatment was 16 days. Patient characteristics at baseline were well balanced between the 2 treatment groups. Mortality was equal in the 2 groups: 10 (4.2%) of 238 patients in the clarithromycin group and 9 (3.8%) of 235 patients in the placebo group (relative risk, 1.10; 95% CI, 0.42-2.89; P=1.0). Also, there were no significant differences in the proportion of patients who experienced cardiovascular events during the follow-up period: 20 (8.4%) of 238 patients in the clarithromycin group and 19 (8.1%) of 235 patients in the placebo group (relative risk, 1.04; 95% CI, 0.55-1.98; P=1.0). The overall rate of such events was 58 (12.3%) of 473 patients.

CONCLUSIONS

Treatment with clarithromycin in patients scheduled for CABG surgery did not reduce the subsequent occurrence of cardiovascular events or mortality during a 2-year follow-up period.

Advances in the management of Chlamydia pneumoniae infections

One of the major characteristics of Chlamydia spp. is its ability to cause prolonged, often subclinical infections. Chronic, persistent infection with Chlamydia pneumoniae has been implicated in the pathogenesis of several chronic diseases initially not thought to be infectious, including asthma, arthritis and atherosclerosis. C. pneumoniae is susceptible in vitro to a wide range of antimicrobial agents that target either protein or DNA synthesis, including macrolides, ketolides, tetracyclines, quinolones and rifamycins. Practically all treatment studies evaluating presented or published to date have used serology alone for diagnosis of C. pneumoniae infection, which only provides a clinical end point. The results of several treatment studies that did perform culture found that erythromycin, azithromycin (Zithromax, clarithromycin (Biaxin, levofloxacin (Levaquin and moxifloxacin (Avelox had a 70 to 90% efficacy in eradicating C. pneumoniae from the respiratory tract of children and adults with pneumonia. Persistence of the organism does not appear to be due to the development of antibiotic resistance. However, one cannot extrapolate from this experience to the treatment of chronic C. pneumoniae infection, especially cardiovascular disease. As there are no reliable serologic markers for chronic or persistent C. pneumoniae infection, it cannot be determined who is infected and who is not, which means that it cannot be assumed that any effect seen is due to successful treatment or eradication of C. pneumoniae.

Antibiotics for vascular diseases: a meta-analysis of randomized controlled trials

BACKGROUND

Trials of antibiotic treatment of vascular diseases, in attempts to eradicate possible microbial initiators, have had mixed results. We sought to evaluate the efficacy of antibiotics in treating patients with atherosclerotic vascular diseases, using a meta-analysis.

METHODS

We searched MEDLINE, EMBASE, and Cochrane Central Register of Controlled Trials and also used cross-references. Randomized controlled trials of antibiotic treatment of vascular diseases were included. Two independent raters assessed the trials for quality. We performed summary estimates, subgroup analyses and tests for homogeneity.

RESULTS

Twelve trials, with a total of 12,236 patients, were included. Antibiotic treatment resulted in a non-significant reduction in the risk of new vascular events or death (odds ratio (OR), 0.84; 95% confidence interval (CI), 0.67-1.05). There was significant heterogeneity between the sub-groups in type of vascular disease (coronary heart disease, CHD versus non-CHD (p=0.01)). Among the 72 non-CHD patients, a trend appears for treatment benefit in reducing recurrent events or death (OR, 0.22; 95% CI, 0.07-0.66).

CONCLUSIONS

Overall, antibiotic treatment did not significantly reduce occurrence of new vascular events or death. However, further trials are needed to confirm the benefit demonstrated in non-CHD patients.

Antibody levels against Chlamydia pneumoniae and outcome of roxithromycin therapy in patients with acute myocardial infarction. Results from a sub-study of the randomised Antibiotic Therapy in Acute Myocardial Infarction (ANTIBIO) trial

BACKGROUND

Results of studies concerning prevention of cardiovascular disease by treatment with macrolide antibiotics targeting C. pneumoniae infection are still controversial. This study describes the results of different tests for infection with C. pneumoniae as well as the effect of treatment with roxithromycin in patients with acute myocardial infarction (AMI) in relation to their serostatus against C. pneumoniae.

METHODS

We analysed blood of 160 patients who came from the ANTIBIOtic therapy after an AMI ( ANTIBIO-) study, a prospective, randomised, placebo-controlled, double-blind study to investigate the effect of roxithromycin 300 mg/OD for 6 weeks in patients with an AMI. Anti- Chlamydia IgG-, IgA-, and IgM-antibodies of these patients were analysed by means of different test systems.

RESULTS

There was a good correlation between the two IgG and IgA methods (r = 0.900, p < 0.001 and r = 0.878, p < 0.001, respectively), but marked differences in the prevalence of positive tests. This resulted in only moderate concordance values, as expressed by the Kappa coefficients, for IgG kappa = 0.611 (95% CI = 0.498-0.724, p < 0.001) and for IgA kappa = 0.431 (95% CI: 0.322-0.540, p < 0.001). No significant association between positive C. pneumonia titers and the combined clinical endpoint during the 12 month follow-up could be found. In all test systems used, patients with positive anti- C. pneumoniae titers did not benefit from roxithromycin therapy (p = ns).

CONCLUSION

Depending on the test system used, there are large differences in the prevalence of anti- C. pneumoniae seropositive patients. Clinical events during the 12 month follow-up after AMI did not depend on serostatus against C. pneumoniae and treatment with roxithromycin did not influence these events, independently of the serostatus against C. pneumoniae. However, the power of this subgroup analysis was low to detect small but significant differences.

Influence of Doxycycline on Clinical and Angiographic Outcome Following Percutaneous Coronary Intervention

BACKGROUND

Infection with Chlamydia pneumoniae may be involved in atherosclerosis. Neointima proliferation after percutaneous coronary intervention (PCI) could be aggravated by proinflammatory action of chronic vascular chlamydial infection. We investigated the influence of doxycycline therapy on restenosis rate and adverse clinical event rates after PCI.

METHODS

We followed 1,019 consecutive patients in a single center nonrandomized observational study. During a 3-month period, all patients having PCI (n = 541; treatment group) received oral doxycycline 100 mg/day for 50 days starting from the day of the procedure. A control group (n = 478) consisted of consecutive post-PCI patients recruited from immediately preceding (n = 250) and ensuing periods. Event rates were gained by questionnaires after 259 +/- 57 days. Restenosis rate was derived from the routine angiographic restudies after 172 +/- 15 days.

RESULTS

No significant differences between treatment and control group were found in adverse clinical event rates (myocardial infarction: 0.7% vs 1.3%; repeat-PCI: 24.0% vs 20.9%; coronary bypass grafting: 5% vs 3.9%; overall death after 6 months: 3.5% vs 2.1%) and overall restenosis rate (21.6% vs 23.4%). A subgroup analysis of nondiabetic male smokers revealed a lower restenosis rate in the treatment group (10.9% vs 30.9%; P = 0.0195).

CONCLUSION

Doxycycline therapy for 50 days following PCI does not appear to have a substantial influence on the clinical and angiographic outcome in unselected patients. The observed reduction in restenosis rate among nondiabetic male smokers defines a new hypothesis that should stimulate further investigations.

Pathogen burden, inflammation, proliferation and apoptosis in human in-stent restenosis. Tissue characteristics compared to primary atherosclerosis

Pathogenic events leading to in-stent restenosis (ISR) are still incompletely understood. Among others, inflammation, immune reactions, deregulated cell death and growth have been suggested. Therefore, atherectomy probes from 21 patients with symptomatic ISR were analyzed by immunohistochemistry for pathogen burden and compared to primary target lesions from 20 stable angina patients. While cytomegalovirus, herpes simplex virus, Epstein-Barr virus and Helicobacter pylori were not found in ISR, acute and/or persistent chlamydial infection were present in 6/21 of these lesions (29%). Expression of human heat shock protein 60 was found in 8/21 of probes (38%). Indicated by distinct signals of CD68, CD40 and CRP, inflammation was present in 5/21 (24%), 3/21 (14%) and 2/21 (10%) of ISR cases. Cell density of ISR was significantly higher than that of primary lesions (977 +/- 315 vs. 431 +/- 148 cells/mm(2); p < 0.001). There was no replicating cell as shown by Ki67 or PCNA. TUNEL(+) cells indicating apoptosis were seen in 6/21 of ISR specimens (29%). Quantitative analysis revealed lower expression levels for each intimal determinant in ISR compared to primary atheroma (all p < 0.05). In summary, human ISR at the time of clinical presentation is characterized by low frequency of pathogen burden and inflammation, but pronounced hypercellularity, low apoptosis and absence of proliferation.

Cytomegalovirus and Chlamydia pneumoniae as predictors for adverse events and angina pectoris after percutaneous coronary intervention

BACKGROUND

The aim of our study was to investigate the influence of prior cytomegalovirus (CMV) or Chlamydia pneumoniae (CP) infection on prognosis after percutaneous coronary intervention (PCI).

METHODS

Using the enzyme-linked immunosorbent assay technique preprocedural anti-CMV immunoglobulin G and anti-CP immunoglobulin A (CP IgA), immunoglobulin M, and immunoglobulin G antibodies were measured. Repeat anginal complaints and major adverse clinical events (MACE), including PCI, coronary artery bypass grafting, myocardial infarction, and death, were recorded at 8-month follow-up.

RESULTS

Six hundred consecutive patients were included after successful PCI. Sixty-four percent of the patients were stented. The mean age was 61.6 years, and 68.9% were male. The rate of seropositivity for CP IgA in patients with MACE as compared with patients without MACE was 50.9% versus 35.4% (P =.0276). In patients with repeat anginal complaints, CP IgA seropositivity was 41.6% versus 34.6% in patients without repeat angina (P =.1057). The negative effect of CP on prognosis was confirmed after calculating the odds ratios for MACE (1.9, 95% CI 1.1-3.3). The rates of seropositivity for anti-CMV immunoglobulin G were not significantly different between both groups, although we found an association between infectious burden and repeat angina pectoris (odds ratio 1.8, 95% CI 1.1-3.0).

CONCLUSIONS

We conclude that preprocedural seropositivity of CP IgA is a risk factor for MACE and angina pectoris after PCI. Although no such relation was found for CMV alone, the cumulative infectious burden was also related to these clinical manifestations of restenosis.

Promoter polymorphism in the CD14 gene and concentration of soluble CD14 in patients with in-stent restenosis after elective coronary stenting

BACKGROUND

Activated monocytes/macrophages, neutrophils, endothelial cells and smooth muscle cells participate in the restenosis processes. Monocytes/macrophages and neutrophils are activated by lipopolysaccharide (LPS) via CD14. Endothelial cells and smooth muscle cells are also stimulated by soluble CD14 (sCD14)-LPS complexes.

METHODS

We tested the hypothesis that C(-260)-->T polymorphism of the CD14 gene and sCD14 might be predictors for in-stent restenosis. We analyzed 129 consecutive patients who underwent elective coronary stenting. The restenosis was defined as > or =50% diameter stenosis at follow-up angiography.

RESULTS

The prevalence of the T/T genotype and the concentration of sCD14 were significantly higher in the restenosis group than in the no-restenosis group. This CD14 polymorphism also affected the levels of sCD14, therefore, we divided the patients into four groups. The loss index was 24.8% in C/C or C/T and < or =50th percentile of sCD14, 35.9% in T/T and < or =50th percentile of sCD14, 44.2% in C/C or C/T and >50th percentile of sCD14, and 49.1% in T/T and >50th percentile of sCD14 (P=0.02). The restenosis rate was 10.0%, 26.7%, 26.2% and 50.0% in each group, respectively (P=0.003). In the multivariate analysis, T/T and >50th percentile of sCD14 was the independent predictor for in-stent restenosis.

CONCLUSIONS

This study showed that the T/T genotype with a high level of sCD14 is an independent predictor of in-stent restenosis. The activation of monocytes/macrophages, endothelial cells and smooth muscle cells mediated by CD14 and/or sCD14 may play an important role in the restenosis processes.

Effects of a brief course of azithromycin on soluble cell adhesion molecules and markers of inflammation in survivors of an acute coronary syndrome: A double-blind, randomized, placebo-controlled study

BACKGROUND

The anti-chlamydial antibiotic, azithromycin, may improve outcome in patients who survive an acute coronary syndrome. The mechanisms are, however, poorly understood. The aims of this study were to define any relationship between Chlamydia pneumoniae seropositivity and levels of specific markers of endothelial activation (soluble cell adhesion molecules) and more general markers of inflammation (C-reactive protein [CRP] and interleukin-6 [IL-6]) and to assess whether azithromycin had any effect on such markers.

METHODS

Patients who survived an acute coronary syndrome were randomized to receive treatment with azithromycin (n = 72) or placebo (n = 69) for 5 days. Before therapy, C pneumoniae IgA and IgG titers were checked, with serum levels of soluble intercellular adhesion molecule-1 (sICAM-1), soluble vascular cell adhesion molecule-1, soluble E-selectin (sE-selectin), soluble P-selectin, high-sensitivity CRP, and IL-6. They were rechecked 3 months later.

RESULTS

There were no significant correlations between C pneumoniae titers and levels of CRP, IL-6, or soluble cell adhesion molecules. However, azithromycin treatment significantly reduced mean sICAM-1 levels (P =.006). This effect was more marked in patients with elevated titers of C pneumoniae IgA and IgG. Soluble E-selectin levels were also reduced in patients who were seropositive, but no effects were seen on other endothelial or inflammatory markers.

CONCLUSIONS

After an acute coronary syndrome, a 5-day course of azithromycin reduces levels of sICAM-1, a marker of endothelial cell activation. Although these data suggest a potentially beneficial role for azithromycin, they should be interpreted with caution.

Macrolide antibiotics: current and future uses

After a long history of anti-infective therapeutic use, macrolide antibiotics have not yet given up all their secrets. Interest in their therapeutic potential in inflammatory diseases (possibly including non-infectious diseases) has generated abundant fundamental research and therapeutic trials worldwide. The main question regarding the future prospects of this class of drugs is whether some macrolides are beneficial in such settings because they modulate host inflammatory responses (and cellular targets) or rather because they eliminate a latent, unidentified pathogen which triggers chronic inflammation. However, no clearcut results have yet been obtained.

[Infectious features of atherosclerosis]

As an inflammatory focus, the atherosclerotic plaque is viewed as a response to aggressions. Suppressing these causal injuries appears as the best means for preventing the disease. Infection is among the clues for answering the etiological challenge of atherosclerosis. Through direct or indirect, and specific or non specific pathways, some candidate viruses or bacteria are suspected to induce or stimulate plaque formation or complications. Yet, none of these working hypotheses has reached the level of proof required for establishing a valid concept. Although submitted to intensive investigations, anti-infectious drugs and antimicrobial vaccinations are still far-sighted expectations in the treatment and prevention of coronary artery disease.