ABO-Rh blood groups distribution in cardiac syndrome X patients.

BACKGROUND: Data on frequency distribution of ABO-Rh blood groups in cardiac syndrome X (CSX) patients are not available. We aimed to investigate the distribution of ABO-Rh blood groups in these patients.
MATERIALS AND METHODS: A total of 247 CSX patients' records were reviewed in a cross-sectional study from 2006 to 2010. One hundred forty six patients (59.1%) were female, and the mean patient age was 52 ± 11 years. The frequency of ABO-Rh blood groups was compared to the frequency of these blood groups in the West-Azerbaijan province, Iran; general population.
RESULTS: Blood groups distribution among CSX patients showed phenotypes A, B, AB, O and Rh negative as 33.1%, 21.9%, 9.3%, 35.8%, and 7.9%, respectively. According to our results, there were no differences in ABO-Rh blood groups distribution between CSX patients and normal population.
CONCLUSION: These data suggest that ABO-Rh blood groups might be unassociated with CSX.

INTRODUCTION

Cardiac syndrome X (CSX) is a combination of several known cardiovascular risk factors that affects at least 20 percent of people in developed countries.[1] Although CSX has been regarded as a condition with an excellent prognosis, newer data show that CSX patients with endothelial dysfunction have an increased risk for future adverse cardiac events.[2] Studying CSX patients may help to identify characteristics that may be protective against the development of coronary artery disease (CAD).[3] Underlying pathophysiological mechanisms responsible for the occurrence of these situations have been the subject of great interest for the last few decades.[4] As known, elevated plasma concentrations of von Willebrand factor (vWF), an endothelial-derived glycoprotein, is a measure of endothelial dysfunction. The vWF is involved in primary hemostasis as well as in thrombogenesis and atherosclerotic vascular disease.[5] It has been reported that genetic factors are responsible for up to 66% of variations in plasma vWF antigen level, of which 30% is related to ABO blood groups.[6] Since endothelial dysfunction is the major pathophysiological mechanism in CSX,[7] it seems that there might be a relationship between ABO-Rh blood groups and CSX. We didn’t find any data regarding the effect of ABO-Rh blood groups on CSX. In this study, we examined the distribution of ABO-Rh blood groups in CSX patients. We also compared frequencies of non-O and O blood groups because according to previous reports, subjects with non-O blood group have an increased prothrombotic tendency.[68-12]

MATERIALS AND METHODS

Two hundred forty seven of CSX patients’ records with available ABO-Rh blood typing were collected in the Department of Cardiology, Urmia, Iran; between 2006 and 2010. The subjects had angina-like pain on effort, ST segment depression on exercise stress test and totally normal coronary arteries at angiography. They comprised 101 (40.9%) males and 146 (59.1%) females; aged 20 – 80 years (mean age, 52 ± 11 years).

The prevalence of ABO blood groups were compared to the frequency of these blood groups in the West-Azerbaijan province, Iran; general population, which have already published by Iranian Blood Transfusion Organization.[13]

Continuous variables are expressed as mean ± SD, and categorical data are expressed as percentages. One-way analysis of variance (ANOVA) was used to evaluate differences in continuous variables across the groups. Chi-square test was used for categorical variables. A P-value of less than 0.05 was considered statistically significant. All analyzes were carried out with SPSS version 16.0 software for Windows.

RESULTS

In our study, age and sex distribution and prevalence of cardiovascular risk factors such as history of smoking, diabetes mellitus, hypertension, and hyperlipidemia was similar in patients with different blood groups. Only gender distribution was different between non-O and O blood types patients [Table 1].

Table 1

Demographic data and clinical characteristics of the study population by blood type

There were no differences in ABO-Rh blood groups distribution between CSX patients and normal population. Also, non-O and O blood type distribution didn’t differ between two groups [Table 2].

Table 2

ABO-Rh blood groups distribution in CSX patients and normal population

DISCUSSION

Our results showed that ABO-Rh blood groups might be unassociated with CSX. This conclusion arises from the observation of a similar distribution of ABO-Rh blood groups among these patients and the West-Azerbaijan general population. We didn’t find any data on frequency distribution of ABO-Rh blood groups in CSX patients, but as stated, Bøtker et al. in their research on plasma concentrations of vWF in CSX patients, CAD patients and healthy controls reported that CSX patients had only insignificantly higher circulating levels of vWF than healthy subjects. They also found a considerable overlap between plasma concentrations of vWF in the 3 study groups. These researchers suggested that CSX patients comprise a heterogeneous group among whom random cases may display elevated levels of vWF. They justified that such heterogeneity may explain why some studies have demonstrated systemic endothelial dysfunction in a limited number of CSX patients.[5] Recent studies suggest that the adverse event rate may be increased in patients with CSX and demonstrable endothelial dysfunction.[21415] We did not analyze the presence or absence of endothelial dysfunction in our studying group, which is a limitation of our project.

Comparing ABO-Rh blood groups distribution of non-O and O blood groups patients showed no association. Numerous studies reported that non-O individuals could have an increased thrombotic risk and CAD via having higher vWF levels.[68-12] For example, Carpeggiani et al. in their research concluded that a non-O blood group is associated with an increased mortality in patients with ischemic heart disease. They proposed ABO blood groups determination for genetic screening of ischemic heart disease.[16] Ketch et al. demonstrated that non-O compared to O blood groups patients have higher thrombus burden despite less extensive atherosclerosis.[17] von Beckerath et al. showed that carriage of the O1 allele is associated with a decreased risk of myocardial infarction, with homozygosity providing the greatest protection.[10] Ray et al. reported elevated absolute levels of vWF in non-O blood groups and concluded that the increased risk of non-O blood groups CAD patients may be related to intrinsically higher circulating levels of vWF.[18] As stated, the similar distribution of ABO-Rh blood groups among CSX patients in our study, indirectly hints to the irrelevant roll of vWF in this syndrome. However, the lack of direct measurements of vWF level or other biological marker of endothelial cell dysfunction precludes a more in-depth understanding. It seems that large scale studies, especially on the basis of endothelial dysfunction, would be helpful to better clarify this subject.