Association Between Cerebral Ischemia and Cytotoxin-Associated Gene-A–Bearing Strains ofHelicobacter pylori

A meta-analysis of the association between Helicobacter pylori infection and risk of atherosclerotic cardiovascular disease

BACKGROUND

Helicobacter pylori (H pylori) infection may be a risk factor for cardiovascular disease (CVD), but the reported researches have given conflicting results.

AIMS

To investigate the association between H pylori infection and risk of atherosclerotic CVD.

MATERIALS AND METHODS

The studies were retrieved in Embase, PubMed, Web of Science (published from Jan 1, 1990, to Jan 31, 2020, language restrictions: English). All studies included used data from case-control studies and cohort studies of cardiovascular adverse events. Random effect models were used to measure pooled estimates. All data were analyzed with Stata 11.2 SE (StataCorp, College Station, TX).

RESULTS

Helicobacter pylori infection increased the risk of adverse cardiovascular events by 51% (40 studies, n = 19 691, odd ratio [OR] = 1.51, 95% confidence interval [CI]: 1.34-1.70). The effect was greater for studies that the type of CVDs was myocardial infarction (MI) and cerebrovascular disease (MI OR = 1.80, 95% CI: 1.42-2.26, cerebrovascular disease OR = 1.54, 95% CI: 1.27-1.89). Meanwhile, CagA seropositive H pylori strains were associated with a significantly increased risk of cardiovascular adverse events based on published research data (OR = 1.73, 95% CI: 1.40-2.14).

CONCLUSION

In conclusion, H pylori infection enhanced the risk of atherosclerotic cardiovascular adverse events, especially in some patients with MI and cerebrovascular disease. This study will provide guidance for the targeted prevention and treatment of CVDs. But this association need to be confirmed by more prospective studies.

Association between Helicobacter Pylori infection and stroke: a meta-analysis of 273,135 patients

BACKGROUND

Stroke stands among the most leading causes of mortality worldwide. Although modifiable risk factors for stroke have been identified, current risk factors do not sufficiently explain the risk in young patients. Previous studies have postulated an association between infection by Helicobacter pylori (HP) and stroke.

OBJECTIVE

To investigate the association between HP infection and stroke by using a systematic review and meta-analysis approach.

METHODS

Four electronic search engines/libraries were systematically searched for relevant observational studies. Studies were screened for eligibility and data were extracted. The odds ratio (OR) and 95% confidence interval (95% CI) were combined under the random-effect model. The protocol was registered in PROSPERO (CRD42019123689).

RESULTS

Among the included studies, 25 studies were analyzed for anti-HP IgG, 9 studies were for anti-Cag A, and 6 studies were for the C-urea breath test. The results showed that positive anti-HP IgG was significantly associated with an increased risk of stroke [OR (95% CI) = 1.43 (1.25-1.46)]. Similarly, both antiCag A and C-urea breath test were significantly associated with an increased risk of stroke with [OR (95% CI) = 1.77 (1.25-2.49)], and [OR (95% CI) = 2.21 (1.33-3.66)], respectively. Furthermore, our results indicated that positive anti-HP IgG was associated with stroke caused by atherothrombosis and small artery disease.

CONCLUSIONS

This study suggests that HP infection is significantly associated with increased risk of stroke. However, more well-designed studies are required to investigate if early HP eradication might decrease the incidence of stroke.

Investigating the association between influenza vaccination and reduced stroke risk

Acute infections, mainly of the respiratory tract, have consistently been demonstrated to considerably increase the risk of stroke. At present, prospective interventional trials are lacking and there is no proof of the effectiveness of any therapeutic anti-infective strategy in stroke prevention. However, some new evidence from observational studies lends support to the idea that influenza vaccination may contribute importantly to fighting stroke. Although final proof of efficacy is still missing, patients with previous cerebral ischemia and subjects of any age at high risk of stroke should be encouraged to receive annual influenza vaccination.

Helicobacter pylori infection contributes to high risk of ischemic stroke: evidence from a meta-analysis

Chronic infection of Helicobacter pylori (H. pylori) in ischemic stroke (IS) incidence has been previously studied in several publications; however, conflicting results have been reported. A meta-analysis was used to assess whether chronic infection of H. pylori was associated with risk of IS, and which of the following was more effective for predication of IS risk, antibody IgG of H. pylori (anti-H. pylori IgG), antibody IgG of cytotoxin-associated gene-A (anti-Cag A IgG) or the (13)C-urea breath test. We searched the databases of Medline and Embase, and latest update was January 1, 2012. Case-control studies were considered to be eligible. The odds ratio (OR) and 95 % confidence interval (95 % CI) were calculated using the random-effect model. A total of 13 studies including 4,041 participants were included in this meta-analysis. Of these studies, ten, four and four studies were for anti-H. pylori IgG, anti-Cag A IgG and the (13)C-urea breath test, respectively. Combined analysis indicated that positive anti-H. pylori IgG, anti-Cag A IgG and (13)C-urea breath test were significantly associated with increased risk of IS, respectively, and positive anti-Cag A IgG was more effective for predication of IS risk [OR (95 % CI) = 1.60 (1.21-2.11), P (heterogeneity) = 0.001 for positive versus negative anti-H. pylori IgG; 2.33 (1.76-3.09), P (heterogeneity) = 0.71 for positive versus negative anti-Cag A IgG and 1.65 (1.11-2.47), P (heterogeneity) = 0.17 for positive versus negative (13)C-urea breath test]. In addition, we found that positive anti-H. pylori IgG was closely associated with risk of IS caused by atherosclerosis and small artery disease, but not for cardioembolic IS. This meta-analysis indicated that chronic H. pylori infection was significantly associated with an increased risk of IS, especially for non-cardioembolic IS. Compared with anti-H. pylori IgG and the (13)C-urea breath test, anti-Cag A IgG seemed more effective for prediction of risk of IS.

Chronic Helicobacter pylori infection and ischemic stroke subtypes

OBJECTIVE

Chronic infection by Helicobacter pylori is regarded as an etiological factor for vascular diseases. However, there are conflicting results on the relevance of chronic infection by Helicobacter pylori as a risk factor for ischemic stroke. The aim of our study was to investigate the association between Helicobacter pylori infection and ischemic stroke subtypes in Chinese.

METHOD

A total of 150 patients with ischemic stroke were enrolled in the patient group. Analyses were stratified for etiologic stroke subtypes according to 2007 modified Trial of Org 10172 in Acute Stroke Treatment criteria: 119 patients with atherothrombosis, 15 patients with cardioembolism, and 12 patients with small artery disease. One hundred and thirty-one control subjects without clinical and instrumental evidence of atherosclerotic diseases were randomly selected from health check-up center. The potential risk factors for Helicobacter pylori infection and traditional risk factors for ischemic stroke of all subjects were analyzed. The serum specific antibody IgG of Helicobacter pylori was detected by enzyme-linked immunosorbent assay. Conditional logistic regression was used to analyze the data.

RESULTS

The Helicobacter pylori/IgG-positive rate in the patient group was higher than that in the healthy control group, but the difference was not statistically significant [67.3% versus 61.8%; odds ratio (OR) = 1.272; P = 0.336]. This result remained non-significant after adjustment for other established risk factors [OR = 1.222; 95% confidence interval (CI): 0.688-2.171; P = 0.494]. Subgroup analysis using univariate and multivariate analyses yielded similar results in all etiologic stroke subtypes (univariate analysis, atherothrombosis: OR = 1.368, 95%CI: 0.810-2.311, P = 0.241; cardioembolism: OR = 0.926, 95%CI:0.311-2.758, P = 0.890; small artery disease: OR = 1.852, 95%CI: 0.478-7.167, P = 0.366; multivariate analysis, atherothrombosis: OR = 1.385, 95%CI: 0.726-2.639, P = 0.323; cardioembolism: OR = 0.832, 95%CI: 0.236-2.932, P = 0.775; small artery disease: OR = 1.836, 95%CI: 0.396-8.503, P = 0.437).

CONCLUSIONS

This case-control study does not reveal any strong association between chronic Helicobacter pylori infection and ischemic stroke. Large case-control prospective studies are required for further investigation of the potential association between Helicobacter pylori infection and ischemic stroke risk, particularly in certain subgroups.

CagA-positive Helicobacter pylori strains enhanced coronary atherosclerosis by increasing serum OxLDL and HsCRP in patients with coronary heart disease

BACKGROUND

The role of infection in the pathogenesis of atherosclerosis is still a matter of debate.

AIMS

This study aimed to investigate the effect of CagA-positive Helicobacter pylori (H. pylori) strains infection on coronary atherosclerosis in patients with coronary heart disease and to elucidate how cytotoxin-associated gene A (CagA)-positive H. pylori strains infections were involved in coronary heart disease by examining the levels of serum lipid, high-sensitivity C-reactive protein (hsCRP) and oxidized low-density protein (oxLDL).

METHODS

Recruited for this study were 159 patients with coronary heart disease. The severity of coronary heart disease was estimated by calculating the Gensini score. Serum oxLDL and hsCRP were examined in all subjects. Current H. pylori infection was determined in all participants by means of a modified (13C) urea breath test (>200 dpm classified as positive). IgG antibodies against CagA protein were analyzed by enzyme immunoassays. Antibody titers against CagA (≥8 U/ml) were classified as positive. All subjects were divided into three groups, including an uninfected group (n=30), an H. pylori +CagA- group (n=69), and an H. pylori +CagA+ group (n=60).

RESULTS

Significant differences were found among the three groups in levels of total cholesterol, low-density lipoprotein cholesterol, apolipoprotein B, serum hsCRP, oxLDL, and severity of coronary atherosclerosis (p<0.05). The levels of total cholesterol, LDL, apolipoprotein B, serum hsCRP, oxLDL were significantly elevated and the severity of coronary atherosclerosis was significantly increased in H. pylori +CagA+ group (p<0.05).

CONCLUSIONS

More serious coronary atherosclerosis was observed in CHD patients with H. pylori +CagA+ infection. H. pylori +CagA+ infection might be involved in coronary atherosclerosis by modifying serum lipids, enhancing LDL oxidation, and activating the inflammatory responses.

Influence of CagA-positive Helicobacter pylori strains on atherosclerotic carotid disease

Citotoxin-associated gene-A (CagA)-positive Helicobacter pylori strains have been associated with occurrence and destabilization of coronary atherosclerotic plaques. However, data on the relationship between CagA-positive H. pylori infection and carotid artery instability are lacking. Thus, the role of CagA antigen in patients with symptomatic and asymptomatic carotid atherosclerotic plaques was investigated. A total of 64 patients with advanced carotid artery stenosis, including 33 patients with symptomatic and 31 patients with asymptomatic internal carotid artery stenosis, verified by duplex ultrasound, all undergoing carotid endarterectomy, were studied. The control group consisted of 65 subjects without a history or presence of vascular diseases. Serology for H. pylori and CagA antigen was assessed in all participants. Specimens of atherosclerotic plaques obtained from all patients during carotid endarterectomy were analyzed immunohistochemically using anti-CagA monoclonal antibodies. The ultrasonographic plaque characteristics were also estimated. CagA antibody titers were significantly higher in symptomatic patients (8.8; range, 5.8-32.7) compared to asymptomatic patients (4.7; range, 2.1-8.8; P = 0.005) and the control group (5.0; range 2.2-7.9; P < 0.001). There was significant difference in echolucency (≥ 25% soft material) between the symptomatic and asymptomatic groups (P = 0.034) by ultrasonographic evaluation. Positive immunoreactivity between monoclonal CagA antibodies and antigens within atherosclerotic specimens was significantly higher among symptomatic patients compared to asymptomatic patients (97.0 vs. 74.2%; P = 0.009). H. pylori may play a role in the pathogenesis of the atherosclerotic process due to autoimmune mechanisms and even contribute to destabilization of carotid atherosclerotic plaques.

Common infections and the risk of stroke

The occurrence of stroke in populations is incompletely explained by traditional vascular risk factors. Data from several case-control studies and one large study using case series methodology indicate that recent infection is a temporarily acting, independent trigger factor for ischemic stroke. Both bacterial and viral infections, particularly respiratory tract infections, contribute to this association. A causal role for infection in stroke is supported by a graded temporal relationship between these conditions, and by multiple pathophysiological pathways linking infection and inflammation, thrombosis, and stroke. Furthermore, observational studies suggest that influenza vaccination confers a preventive effect against stroke. Case-control and prospective studies indicate that chronic infections, such as periodontitis, chronic bronchitis and infection with Helicobacter pylori, Chlamydia pneumoniae or Cytomegalovirus, might increase stroke risk, although considerable variation exists in the results of these studies, and methodological issues regarding serological results remain unresolved. Increasing evidence indicates that the aggregate burden of chronic and/or past infections rather than any one single infectious disease is associated with the risk of stroke. Furthermore, genetic predispositions relating to infection susceptibility and the strength of the inflammatory response seem to co-determine this risk. Here, we summarize and analyze the evidence for common acute and chronic infectious diseases as stroke risk factors.

Infectious burden and risk of stroke: the northern Manhattan study

OBJECTIVE

To determine the association between a composite measure of serological test results for common infections (Chlamydia pneumoniae, Helicobacter pylori, cytomegalovirus, and herpes simplex virus 1 and 2) and stroke risk in a prospective cohort study.

DESIGN

Prospective cohort followed up longitudinally for median 8 years.

SETTING

Northern Manhattan Study. Patients Randomly selected stroke-free participants from a multiethnic urban community. Main Outcome Measure Incident stroke and other vascular events.

RESULTS

All 5 infectious serological results were available from baseline samples in 1625 participants (mean [SD] age, 68.4 [10.1] years; 64.9% women). Cox proportional hazards models were used to estimate associations of each positive serological test result with stroke. Individual parameter estimates were then combined into a weighted index of infectious burden and used to calculate hazard ratios and confidence intervals for association with risk of stroke and other outcomes, adjusted for risk factors. Each individual infection was positively, though not significantly, associated with stroke risk after adjusting for other risk factors. The infectious burden index was associated with an increased risk of all strokes (adjusted hazard ratio per standard deviation, 1.39; 95% confidence interval, 1.02-1.90) after adjusting for demographics and risk factors. Results were similar after excluding those with coronary disease (adjusted hazard ratio, 1.50; 95% confidence interval, 1.05-2.13) and adjusting for inflammatory biomarkers.

CONCLUSIONS

A quantitative weighted index of infectious burden was associated with risk of first stroke in this cohort. Future studies are needed to confirm these findings and to further define optimal measures of infectious burden as a stroke risk factor.

CagA antigen of Helicobacter pylori and coronary instability: insight from a clinico-pathological study and a meta-analysis of 4241 cases

BACKGROUND

Cytotoxin-associated gene-A (CagA) antigen is expressed by some virulent strains of Helicobacter pylori (H. pylori). The role of CagA antigen in coronary instability is unknown. We performed a clinico-pathological study and a meta-analysis in the attempt to shed new light on this complex issue.

METHODS

In the clinico-pathological study, 38 patients with unstable angina (UA), 25 patients with stable angina (SA), 21 patients with normal coronary arteries (NCA) and 50 age and sex matched healthy volunteers were enrolled. Serology for CagA was assessed in all patients. Specimens of atherosclerotic plaques were obtained from all patients by directional coronary atherectomy, and prepared for immunohistochemistry using anti-CagA monoclonal antibodies. The meta-analysis includes 9 studies assessing the association between seropositivity to CagA strains and acute coronary events.

RESULTS

The titre of anti-CagA antibodies was significantly higher in patients with unstable angina (161+/-90 RU/ml) compared to those with stable angina (83+/-59 RU/ml p<0.02), NCA (47.3+/-29 RU/ml p<0.01) and healthy controls (73+/-69 p<0.02). Anti-CagA antibodies recognized antigens localized inside coronary atherosclerotic plaques in all specimens from both stable and unstable patients. In the meta-analysis, seropositivity to CagA was significantly associated with the occurrence of acute coronary events with an odds ratio (OR) of 1.34 (95% CI, 1.15-1.58, p=0.0003).

CONCLUSIONS

Taken together these findings suggest that in a subset of patients with unstable angina, an intense immune response against CagA-positive H. pylori strains might be critical to precipitate coronary instability mediated by antigen mimicry between CagA antigen and a protein contained in coronary atherosclerotic plaques.

Cytotoxin-associated Gene-A-positive Helicobacter pylori strains infection increases the risk of recurrent atherosclerotic stroke

BACKGROUND

CagA-positive Helicobacter pylori infection has been found to be associated with a first-ever atherosclerotic stroke. The aim of this study was to investigate whether these strains represent an independent risk factor for recurrent atherosclerotic stroke.

MATERIALS AND METHODS

We performed a longitudinal study of patients with a first-ever large vessels stroke and resulted positive at H. pylori serology. Patients had clinical examination 1 month after the acute event, and were subsequently visited or contacted by telephone up to 3 years at 6-month intervals. Sera obtained at the time of enrollment were frozen and analyzed for the presence of anti-CagA antibodies at the end of the study. The primary outcome event was any fatal or nonfatal stroke after the index stroke.

RESULTS

One hundred seventy H. pylori-positive patients were included (n = 68 CagA positive and n = 102 CagA negative). No significant difference regarding age and other stroke risk factors was detected. According to Kaplan-Meier survival analysis, CagA-positive patients showed a significantly higher risk for stroke recurrence than CagA-negative ones (45.6% vs 17.6%; p < .001). Difference in the rate of recurrent stroke between the two groups persisted after Cox regression analysis taking into account possible confounding factors (hazard ratio = 3.5; 95% CI = 1.9-6.4; p < .001).

CONCLUSIONS

Infection with H. pylori CagA-positive strains increases the risk of recurrent atherosclerotic stroke. Seropositivity determination should be performed in order to identify high-risk patients requiring a strict clinical surveillance, and the possible beneficial effect of eradication therapy should be evaluated.

Relationship between the cytotoxin-associated gene-A status of H pylori strains and cerebral infarction in European Caucasians and Chinese Han: A meta-analysis

AIM: To study the relationship between the cytotoxin-associated gene-A (CagA) status of H pylori strains and cerebral infarction among European Caucasians and Chinese Han by conducting a meta-analysis.

METHODS: Ten case-control studies, with data on a total of 907 cases and 966 controls, were retrieved and considered; disqualified studies were excluded. The included studies were then tested for heterogeneity, and a meta-analysis was performed.

RESULTS: The combined data revealed CagA-bearing strains of H pylori which cause chronic infection are associated with an increased risk of cerebral infarction (OR = 2.66, 95% CI: 2.17-3.26), but no such relationship was found with CagA-negative strains (OR = 0.74, 95% CI: 0.49-1.10) in the overall population. We performed subgroup analyses, dividing the overall population into European Caucasians and Chinese Han subgroups, and analyzed the studies according to their subgroup classification. Through the subgroup analysis, an association between cerebral infarction and CagA-bearing strains was found in both subgroups (OR = 2.60, 95% CI: 1.93-3.49 in Chinese Han; OR = 2.71, 95% CI: 2.05-3.59 in European Caucasians), but no significant association was found between cerebral infarction and CagA-negative strains (OR = 0.81, 95% CI: 0.45-1.48 in Chinese Han; OR = 0.64, 95% CI: 0.37-1.09 in European Caucasians).

CONCLUSION: These results suggest CagA-bearing strains of H pylori are significantly associated with susceptibility to cerebral infarction in Chinese Han and European Caucasians, but that CagA-negative strains are not a definite predisposing factor in either subgroup. The magnitude of this association with cerebral infarction needs to be confirmed by prospective studies and combined studies of H pylori eradication.

[Does Helicobacter pylori infection play a role in extragastric diseases?]

Since the discovery of Helicobacter pylori (H. pylori), numerous studies have considered the possibility that it plays a role in different extragastric diseases. Most of these studies may be classified as epidemiological studies or investigations of H. pylori eradication, but there are also case reports and in vitro studies. This review reveals the limitations common to most of them. Idiopathic thrombocytopenic purpura is the disease for which the strongest association with H. pylori infection has been shown. Data are also accumulating about the role of H. pylori infection in idiopathic iron deficiency anemia and chronic idiopathic urticaria. Interesting results show that H. pylori infection affects atherosclerosis and is weakly associated with ischemic heart disease and stroke. Moreover, CagA-positive H. pylori strains may play a role in the natural history of atherosclerotic stroke. Recent studies suggest a link between H. pylori and Parkinson's disease. Preliminary data indicate that H. pylori infection impairs gastric ghrelin production and may influence nutritional status. The association between H. pylori infection and other extragastric diseases remains controversial. H. pylori infection may cause extragastric manifestations directly or indirectly, by various mechanisms including atrophic gastritis, the release of inflammatory mediators, molecular mimicry, and systemic immune response. Evidence suggests that anti-H. pylori therapy improves idiopathic thrombocytopenic purpura (significant increase of platelet count in half of the cases), iron-deficiency anemia, and chronic urticaria (30% remission rate), but the data from randomized controlled trials are insufficient to confirm these positive effects.

Current management of Helicobacter pylori infections in the elderly

Helicobacter pylori infection is a chronic gastric gram-negative infection that increases with age worldwide. However, the percentage age of H. pylori-positive elderly patients who are tested and treated for their infection remains very low. It is now demonstrated that H. pylori infection induces a whole cascade of events leading to gastric pathologies, such as peptic ulcer diseases, gastric precancerous lesions and gastric cancer. Recent data also demonstrated that H. pylori chronic infection can play a role in gastric aging, appetite regulation and extradigestive diseases, such as Alzheimer's disease, in the elderly. The diagnosis of H. pylori infection remains difficult to realize in the very old population, and the urea breath test obtains the best performance in this population. 1-week proton pump inhibitor-based triple therapy regimens are highly effective and well tolerated in elderly patients, and antibiotic resistance remains very low. Low compliance is the main factor related to treatment failure in this population.

Infection à Helicobacter pylori chez la personne âgée

PURPOSES

Helicobacter pylori (H. pylori) infection is a chronic gastric Gram-negative infection that increases with age. Acquired in childhood, H. pylori infection may induce a whole cascade of events leading to gastric pathologies such as peptic ulcer diseases, gastric precancerous lesions, and gastric lymphomas (MALT). The characteristics of the diagnosis and the treatment of this infection in geriatrics are thus particularly important to take into account.

MAIN POINTS

1) The incidence of gastric and duodenal ulcers and their bleeding complications is increasing in old-aged populations. Clinical signs such as anorexia and malnutrition are proven to be excellent indications for endoscopic explorations in the elderly. NSAID-use and H. pylori infection were shown to be independent and unrelated risk factors for peptic ulcer and gastroduodenal bleeding in elderly subjects; 2) H. pylori infection diagnosis is difficult to realize in the very old population, and the urea breath test is the test which obtain the best performances in this population.

PERSPECTIVES

Recent work showed the part played by H. pylori chronic infection in gastric aging and in appetite regulation in the elderly. Research tasks should be continued in this field in order to better understand the part played by this chronic infection in gastric aging and in other pathologies (i.e. neurological or cardiovascular diseases) in this population.

No associations of Helicobacter pylori infection and gastric atrophy with plasma total homocysteine in Japanese

Recent studies have suggested that Helicobacter pylori (H. pylori) infection might be a risk factor for atherosclerosis. Since the bacterium has not been isolated from atherosclerotic lesions, a direct role in atherogenesis is not plausible. We examined associations of plasma total homocysteine (tHcy) and serum folate, independent risk factors for atherosclerosis, with H. pylori infection and subsequent gastric atrophy among 174 patients (78 males and 96 females) aged 20 to 73 years, who visited an H. pylori eradication clinic of Nagoya University from July 2004 to October 2005. Polymorphism genotyping was conducted for methylenetetrahydrofolate reductase (MTHFR) C677T and thymidylate synthase (TS) 28-bp tandem repeats by PCR with confronting two-pair primers and PCR, respectively. H. pylori infection and gastric atrophy were not significantly associated with hyperhomocysteinemia (tHcy > or = 12 nmol/ml), when adjusted by sex, age, smoking, alcohol, and genotypes of MTHFR and TS. The adjusted odds ratio of gastric atrophy for low folate level (< or = 4 mg/ml) was 0.21 (95% confidence interval = 0.05-0.78). The associations of tHcy with serum folate and MTHFR genotype were clearly observed in this dataset. The present study demonstrated that folate and MTHFR genotype were the deterministic factors of plasma tHcy, but not H. pylori infection and subsequent gastric atrophy, indicating that even if H. pylori infection influences the risk of atherosclerosis, the influence may not be through the elevation of homocysteine.

Infection as a risk factor for stroke

Persisting disability requiring professional healthcare or help in daily life activities can be expected in a third to a half of all stroke survivors. It is mainly the elderly that are affected. For the increasingly aging population of Western societies, stroke represents an increasing social and economic burden. Besides the existing therapeutic options, additional treatment and prevention strategies are needed. Traditional risk factors do not explain all clinical and epidemiological features of stroke. Recently, the association between infectious and inflammatory processes and the occurrence of vascular disease has been established. This review summarizes the current evidence of infections as stroke risk factors and of potential anti-infective strategies as future methods of stroke prevention.

Virulent strains of Helicobacter pylori and vascular diseases: a meta-analysis

BACKGROUND

Cytotoxin-associated gene A (CagA)-positive strains of Helicobacter pylori are an etiological factor for peptic ulcer and gastric cancer. Studies on the role of these virulent strains in vascular diseases yield conflicting results.

METHODS

We searched the MEDLINE database for relevant studies. Meta-analysis was performed using the random effects method.

RESULTS

We found 10 retrospective case-control studies (with 1527 case patients and 1661 control subjects) and 3 prospective cohort studies (with 701 case patients and 1439 control subjects) on CagA status and ischemic heart disease and 4 retrospective case-control studies (with 513 case patients and 590 control subjects) on CagA status and cerebral ischemia. In the case-control studies, an association of ischemic heart disease with CagA-positive strains (OR 1.87, 95% CI 1.46-2.40) but no significant association with CagA-negative strains (OR 1.15, 95% CI 0.83-1.60) has been found; in the 3 prospective studies, association with ischemic heart disease was weaker but still significant (OR 1.26, 95% CI 1.05-1.51). In the 4 case-control studies, CagA-positive strains were significantly associated with cerebral ischemia (OR 2.43, 95% CI 1.89-3.13), again with no association for CagA-negative strains.

CONCLUSIONS

We found a small but significant association between vascular diseases and virulent CagA-positive strains of H. pylori. The lack of association with CagA-negative strains further supports the hypothesis of an independent relationship between virulent strains of H. pylori and vascular diseases. The magnitude of the association with cerebral ischemia needs to be confirmed by prospective studies.

Primary Prevention of Ischemic Stroke

Background and Purpose— This guideline provides an overview of the evidence on various established and potential stroke risk factors and provides recommendations for the reduction of stroke risk.

Methods— Writing group members were nominated by the committee chair on the basis of each writer’s previous work in relevant topic areas and were approved by the American Heart Association Stroke Council’s Scientific Statement Oversight Committee. The writers used systematic literature reviews (covering the time period since the last review published in 2001 up to January 2005), reference to previously published guidelines, personal files, and expert opinion to summarize existing evidence, indicate gaps in current knowledge, and when appropriate, formulate recommendations based on standard American Heart Association criteria. All members of the writing group had numerous opportunities to comment in writing on the recommendations and approved the final version of this document. The guideline underwent extensive peer review before consideration and approval by the AHA Science Advisory and Coordinating Committee.

Results— Schemes for assessing a person’s risk of a first stroke were evaluated. Risk factors or risk markers for a first stroke were classified according to their potential for modification (nonmodifiable, modifiable, or potentially modifiable) and strength of evidence (well documented or less well documented). Nonmodifiable risk factors include age, sex, low birth weight, race/ethnicity, and genetic factors. Well-documented and modifiable risk factors include hypertension, exposure to cigarette smoke, diabetes, atrial fibrillation and certain other cardiac conditions, dyslipidemia, carotid artery stenosis, sickle cell disease, postmenopausal hormone therapy, poor diet, physical inactivity, and obesity and body fat distribution. Less well-documented or potentially modifiable risk factors include the metabolic syndrome, alcohol abuse, drug abuse, oral contraceptive use, sleep-disordered breathing, migraine headache, hyperhomocysteinemia, elevated lipoprotein(a), elevated lipoprotein-associated phospholipase, hypercoagulability, inflammation, and infection. Data on the use of aspirin for primary stroke prevention are reviewed.

Conclusion— Extensive evidence is available identifying a variety of specific factors that increase the risk of a first stroke and providing strategies for reducing that risk.

The effect of infections and vaccinations on stroke risk

There is increasing evidence that, in addition to conventional risk factors, acute and chronic infectious diseases increase the risk of stroke. Acute infection, mainly respiratory, and both bacterial and viral infection, represent temporarily active trigger factors for cerebral ischemia. Chronic infectious diseases that may increase the risk of stroke include periodontitis, chronic bronchitis and infections with microbial antigens, such as Helicobacter pylori and Chlamydia pneumoniae. From observational studies, there is evidence that vaccination against influenza is associated with a reduced risk of stroke, myocardial infarction and all-cause mortality. This report provides an overview on the influence of infection on stroke risk and potential anti-infective strategies that may play a future role in stroke prevention.

Helicobacter pylori and extragastric diseases--other Helicobacters

The involvement of Helicobacter pylori in the pathogenesis of extragastric diseases continues to be an interesting topic in the field of Helicobacter-related pathology. Although conflicting findings have been reported for most of the disorders, a role of H. pylori seems to be important especially for the development of cardiovascular and hematologic disorders. Previously isolated human and animal Helicobacter sp. flexispira and "Helicobacter heilmannii" strains have been validated using polyphasic taxonomy. A novel enterohepatic Helicobacter has been isolated from mastomys and mice, adding to the list of helicobacters that colonize the liver. Genetic targets that may aid the classification of novel Helicobacter species have emerged. Animal models of Helicobacter-induced gastric and hepatobiliary diseases have offered insights to the mechanisms associated with premalignant transformation.

Role of anti-infective strategies in the prevention of stroke

Case-control studies and a few prospective studies have indicated that chronic infections may add to the risk of stroke and that acute infections may act as trigger factors for stroke. Such chronic infections include periodontal disease, infection with Chlamydia pneumoniae or Helicobacter pylori, and chronic bronchitis. A causal role of these infectious diseases has not been proved, given conflicting study results, possible residual confounding in observational studies, and the lack of evidence from interventional trials. Therefore, special treatment regimens for stroke prevention based on serologic or genomic evidence of infection are not indicated outside of randomized studies at present. However, the preliminary available evidence suggests that in patients with previous cerebral ischemia, clinically diagnosed chronic infections should be taken seriously and should receive the treatment that is indicated according to current guidelines. This may include appropriate treatment of moderate or severe periodontitis and of chronic bronchitis. Inflammatory parameters (eg, C-reactive protein, leukocyte count, fibrinogen) are independently associated with the risk of first or recurrent stroke. The question of whether these indexes are causally related to stroke or merely represent risk markers is not sufficiently clarified. Their use in monitoring individual risk in daily clinical practice is limited at present by the lack of clearly defined therapeutic strategies to modify these parameters, although statins and other drugs can influence inflammatory markers. Observational studies have shown that influenza vaccination is significantly and independently associated with a reduced risk of stroke and myocardial infarction. Although interventional studies in stroke are lacking, it is recommendable that in accordance with current guidelines patients with previous vascular disease, including stroke, patients with high risk of stroke, and all subjects above age 60, receive an influenza vaccination annually.

Toward the definition of cerebral arteriopathies of childhood

PURPOSE OF REVIEW

To facilitate and standardize the diagnosis of cerebrovascular conditions in childhood, particularly in the field of arterial ischemic diseases.

RECENT FINDINGS

Progress in diagnostic techniques in the past decade have led to newly established etiologies for childhood stroke, most of which represent some form of vascular pathology. These advances must be integrated into a modern nomenclature system with revised definitions of stroke and arterial wall diseases-arteriopathies-in childhood.

SUMMARY

This nomenclature system is intended to facilitate and enhance clinical research in childhood stroke, particularly multicenter collaborative studies.