Introduction

Cardiovascular diseases are the leading cause of mortality worldwide1. According to the latest reports published by the American Heart Association (AHA) in 2024, 19.05 million deaths worldwide were attributed to coronary heart disease (CHD). Additionally, in the same year, 244.1 million people were living with ischemic heart disease (IHD), with a higher prevalence in men than women (5.8% and 4.6%, respectively)2. Therefore, the diagnosis, awareness, and treatment of this disease undoubtedly play a crucial role in its mortality rate. Gender-related roles and physiological differences between men and women can influence the presentation of symptoms of angina and effective awareness3. Typically, women have a higher body awareness than men4. This potentially leads to women experiencing greater sensitivity and fewer typical features of chest pain. Moreover, reports indicate that due to the higher levels of estrogen in young women before menopause, compared to postmenopausal women with lower estrogen levels, they have a better pain perception5. Furthermore, angiography and coronary angioplasty are essential methods for diagnosing and treating patients with coronary artery disease. On the other hand, understanding gender differences in angiographic findings can also play a role in treatment6.

Why is this study conducted?

Given their role as primary care providers, nurses can significantly impact the early diagnosis and treatment of coronary artery disease (CAD). Understanding the divergent manifestations of CAD between genders can facilitate more accurate assessments and timely interventions, ultimately improving patient outcomes7,8. By comprehending gender disparities in CAD care delivery, nurses can employ tailored treatment strategies for their patients. These strategies may involve prioritizing specific interventions, recommending lifestyle modifications, and advocating for further diagnostic tests tailored to the sex-specific risks of each patient.

So far, studies on gender differences in symptoms and angiographic findings have been conducted, but they have yielded inconsistent results. Cho et al. (2020), in their study conducted among Koreans, reported that men experience more pain compared to women3. This is in contrast to Granot et al. (2004), who found significantly higher chest pain intensity in women than in men9. Sharma et al. (2022) reported a significant relationship between male gender and typical chest pain in all analysed models in relation to the presence of CAD10. Kim et al. (2022) concluded in their study that in patients with chest pain who underwent invasive CAG, men had a higher prevalence of obstructive CAD and higher-risk angiographic findings such as left main (LM) or three-vessel disease (3VD)6. However, Sayed (2022) reported in a study conducted in Saudi Arabia that CAD severity is not related to gender differences8. Therefore, given the limitations and contradictions in existing studies, greater attention in this area is essential.

Hypothesis

There is a significant association between patient sex and both coronary artery angiography findings and angina pain patterns in patients with myocardial infarction.

The purpose of the study

The aim of this study is to investigate and compare coronary artery angiography findings and chest angina pain patterns based on sex in patients with myocardial infarction.

Methods

Design, settings, and participants

The present study is a cross-sectional and community-based research conducted on all hospitalized patients at the Bushehr Heart Centre, Bushehr, Iran, located in the northern Persian Gulf region. This study was carried out from May 17, 2023, to September 23, 2023, for a duration of 5 months. Simple random sampling was employed to select participants from among hospitalized patients based on the patient information registration system in the hospital. The inclusion criteria for this study were a diagnosis of myocardial infarction (MI) by a specialist physician, consent to undergo angiography, willingness to participate in the study, no history of previous myocardial infarction, and no prior experience of angina pain. Another inclusion criterion was that patients whose coronary angiography revealed at least one coronary artery with a stenosis of 50% or greater were included in the study. The exclusion criteria for the study included the absence of angina pain and the absence of coronary artery obstruction following angiography. Furthermore, patients whose coronary angiography demonstrated less than 50% stenosis in the coronary arteries were excluded from the study. Patients with less than 50% coronary artery stenosis may have experienced myocardial infarction due to mechanisms other than obstructive atherosclerosis (e.g., transient thrombosis, spasm, embolism, or inflammatory injury)11,12,13. These groups may exhibit different clinical profiles, treatment responses, prognoses, and potentially distinct symptoms; therefore, they were excluded from the study14,15,16.

The sample size was calculated using PASS software, considering an Effect Size of 0.2, a Type I error rate of 0.05, and a test power of 0.8 in a chi2 test and to examine the relationship between gender and pain quality, the analysis was performed with 4 degrees of freedom, resulting in a sample size of 299 individuals. With a 20% dropout rate, a total of 374 individuals were considered.

Data collection procedure and instruments

Researchers visited the hospital and were stationed in the emergency department. After a patient’s admission to the department, they assessed the patients’ clinical condition alongside a specialist physician. If a physician diagnosed the patient with a heart attack based on clinical symptoms, written consent was obtained from the patient according to the inclusion criteria, and they were enrolled in the study. For some patients for whom the specialist physician in the initial evaluation could not definitively diagnose MI based on clinical symptoms and electrocardiography (ECG) and had suspicion of MI, troponin testing was performed. If the troponin test came back positive, the patient was included in the study. Initially, patients who were diagnosed with MI by a cardiologist and were candidates for angiography completed the questionnaires. Subsequently, after angiography, patients with less than 50% coronary artery stenosis were excluded from the study based on the exclusion criteria, and their completed questionnaires were not included in further analyses. The data collection instruments in this study included a demographic and clinical information form, a chest pain assessment checklist, and an angiography report checklist.

The demographic and clinical information form collected data on patients’ gender, age, place of residence, marital status, educational level, occupation, number of children, systolic and diastolic blood pressure, heart rate, cardiac risk factors, laboratory findings (White blood cell, Haemoglobin, RBC, Platelets, FBS, BS, Total cholesterol, Low-density lipoprotein cholesterol (LDL), High-density lipoprotein cholesterol (HDL), Triglycerides, PT, PTT, and blood group), and medications used.

Chest pain assessment checklist

This checklist has been designed by the researchers of the current study. The validity of the tool was confirmed using content validity by six faculty members of Bushehr University of Medical Sciences and specialists in the field of cardiology. This checklist includes information about the location of pain, the body part to which the pain radiates, the presence of fatigue, the presence of shortness of breath, factors that exacerbate the pain, the type of pain, pain intensity, the onset time, accompanying symptoms, changes in pain during walking and climbing stairs, pain improvement methods, pain duration, time of pain recurrence, and pain in another body part.

Angiography report checklist

This is a standardized checklist designed by the Ministry of Health, Treatment, and Medical Education of Iran and distributed to hospitals. This checklist is placed in the medical records of all patients undergoing angiography.

Ethical consideration

This study has been reviewed and approved by the ethics committee of Bushehr University of Medical Sciences and has an ethics code of IR.BPUMS.REC.1401.002. Participants were also informed that participation in the research is voluntary, and due to the confidentiality of individuals’ information, their names will not be included in the questionnaire. In addition, informed consent was obtained from the participants based on the Helsinki Declaration.

Data analysis

Data analysis was performed using the Statistical Package for the Social Sciences (SPSS) version 22 (SPSS Inc., Chicago, IL, USA). Descriptive statistics such as mean, standard deviation for quantitative variables, and frequency and percentage for qualitative variables were used for descriptive data analysis. Chi-square tests, Fisher’s exact test, independent T-tests, and logistic regression were used for data analysis. A significance level of 0.05 was considered for all analyses.

Result

Sociodemographic characteristics

Out of the 355 patients who participated in the study, 14 patients were excluded from the study due to normal angiography reports (response rate = 96%). The study included 341 patients with a mean age of 57.8 ± 11.5 years, consisting of 203 (59.5%) males and 138 (40.4%) females. Table 1 presents the clinical demographics comparing men and women. The mean age of men was 56.89 ± 11.03 years, and the mean age of women was 59.14 ± 12.07 years. The prevalence of current smoking and hookah use was higher among men than women. However, other cardiovascular risk factors, including hypertension, diabetes mellitus, and fasting glucose, differed between genders (p-value < 0.05). Mean body mass index, systolic blood pressure (mmHg), and diastolic blood pressure (mmHg) were similar between women and men (p-value > 0.05). Similarly, women had lower blood haemoglobin levels and higher levels of total cholesterol, low-density lipoprotein cholesterol, triglycerides, and high-density lipoprotein cholesterol compared to men. Among cardiovascular medications, beta-blockers were more frequently prescribed to women than men (Table 1).

None of the patients had received thrombolytic therapy. All patients were receiving different doses of atorvastatin, aspirin, clopidogrel, and sublingual nitro-glycerine.

Table 1 Demographic and clinical characteristics of the studied patients according to gender (n = 341).
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Sex differences in angiographic findings

The angiography findings in men and women in the overall study population are presented in Table 2.

The analysis was conducted at the per-patient level. For each coronary artery with stenosis of 50% or greater, a logistic regression was performed. In the univariate model, gender was included, while in the multivariate model, known confounders17,18,19,20 were simultaneously incorporated.

Multivariate statistical test results indicated that among coronary arteries, significant stenosis of the Mid-LCX artery was only observed between the two genders (OR = 4.867, p-value = 0.035). This implies that the stenosis of the Mid-LCX artery in women was more than four times that in men.

Furthermore, other findings revealed that stenosis in the Total LAD, Mid-LAD, Total LCX, Distal LCX, RCA Total, PDA, and PLA arteries was higher in women than in men. On the other hand, among coronary arteries, stenosis in the Proximal LAD, Distal LAD, Diagnosed LAD, Septal LAD, Proximal LCX, Proximal RCA, Mid-RCA, and Distal RCA arteries was more prevalent in men than in women. Finally, the results indicated that overall stenosis in the three arteries, Total LAD, Total LCX, and Total RCA, was higher in women than in men. However, none of these differences showed statistical significance (p-value > 0.05).

In all performed logistic regressions, multicollinearity was assessed using the Variance Inflation Factor (VIF), and all VIF values were < 5. Additionally, model goodness-of-fit was evaluated using the Hosmer–Lemeshow test, and influential observations were examined through Cook’s distance and leverage values.

Table 2 Logistic regression analysis of a single variable and multiple variables for angiography findings based on gender (n = 341).
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Sex differences in chest pain findings

The mean intensity of pain scores in men (6.30 ± 1.80) was higher than in women (6.00 ± 1.91) (p-value = 0.141). No significant differences were found regarding the quality of pain between men and women. However, more men reported that their type of pain was squeezing (p-value = 0.515). Based on these findings, 69% of people experienced chest pain in the center of their chest. Additionally, more women than men complained of left-sided chest pain (p-value = 0.078). Pain lasting longer than 10 min was more common in men (68.5% in men vs. 63.8% in women, p-value = 0.413). Moreover, chest pain was exacerbated by exercise in some individuals (p-value = 0.825). Furthermore, dizziness was significantly more common in women than in men (p-value = 0.041). In this sample, no gender differences were observed in the timing of onset of pain and the timing of the last pain episode (P > 0.05) (Table 3).

Table 3 Chest pain characteristics according to sex in total population (n = 341).
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Investigating the relationship between sociodemographic variables and occlusions in LAD, RCA, and LCX

Among sociodemographic variables, marital status (p-value = 0.019, Married = 86.9%, Single = 13.1%), family history (p-value = 0.044, No family history = 36.3%, Mother = 29.0%, Grandfather or grandmother = 0.6%), and blood type (p-value = 0.001, A Negative = 50.0%, O Positive = 1.0%) showed significant associations. The remaining sociodemographic variables examined in this study did not have a significant relationship with LAD occlusion.

Among the demographic variables, none of the variables had a significant association with the stenosis of the RCA artery (p-value > 0.5).

Among sociodemographic variables, family history (p-value = 0.040, No family history = 39.9%, Mother = 26.2%, Grandfather or grandmother = 0.4%) showed a significant association. The other sociodemographic variables examined in this study did not have a significant relationship with LCX occlusion.

Investigating the relationship between chest pain characteristics and occlusions in LAD, RCA, and LCX

Chest pain at rest (p-value = 0.042, Yes = 38.2%, No = 61.8%), feeling tired during activity (p-value = 0.051), shortness of breath during activity (p-value < 0.001), climbing stairs (p-value = 0.043), walking on level ground (p-value = 0.007), how often pain occurred (p-value = 0.024, Not remember = 37.6%, weekly = 33.4%), onset of pain within the last 7 days (p-value = 0.006), and pain severity rated 7 out of 10 (p-value = 0.032) were associated with LAD occlusion.

Chest pain accompanied by shortness of breath (p-value = 0.034), experiencing pain while walking on level ground (p-value = 0.050), relief of pain with rest (p-value = 0.024), and pain severity rated 6 out of 10 (p-value = 0.030) were associated with LCX occlusion.

Feeling tired (p-value = 0.04) and experiencing pain while walking on level ground (p-value = 0.010), and pain severity rated 6 out of 10 (p-value = 0.285) were associated with RCA occlusion.

Discussion

The present study aimed to examine and compare the angiographic findings of coronary arteries and the pattern of angina pain based on gender at the Heart Centre of Bushehr, Iran.

Sex differences in angiographic findings

The present study results indicated that stenosis of the Mid-LCX artery in women was more than four times that in men, and this difference was statistically significant. To explain this finding, it can be noted that, considering the differences in size and structure of the heart between women and men, women have smaller hearts and thinner myocardial walls21,22,23. Consequently, in women, cholesterol accumulation is often observed in smaller blood vessels24. Additionally, the findings also showed that overall stenosis in three arteries—Total LAD, Total LCX, and Total RCA—was higher in women than in men. However, none of these differences showed statistical significance. In explaining this result, it can be mentioned that although menopause and early menopause were not addressed in the current study, the observed result might be related to menopause in women. According to the World Health Organization, the average onset age of menopause is between 45 and 55. Some women may also experience early menopause before the age of 4025. This is noteworthy as the average age of women participating in the current study was 59.14. Therefore, considering the effects of estrogen reduction in menopause, such as increased LDL26, decreased vascular flexibility27, insulin resistance, and increased inflammation in the cardiovascular system28, as well as the current study results indicating significant differences in cholesterol levels and diabetes mellitus prevalence in women compared to men, and higher levels of blood sugar and fasting blood sugar in women compared to men, all these factors could contribute to the development and progression of atherosclerosis in women.

Kim et al. (2022) reported a higher prevalence of CAD and associated angiography findings in men, indicating a higher risk6. These results differ from the findings of the present study. Other findings by Kim et al. showed that stenosis in Total LAD and Total LCX was higher in women than in men. Although no statistically significant difference existed between the two genders, the percentage of incidence aligns with the results of the current study. They also demonstrated that Total RCA was more prevalent in men than in women, and a statistically significant difference was observed, which contrasts with the results of the present study. In Kim’s study, LM disease prevalence was 3.8% in men and 1% in women, whereas in the current study, angiography data did not indicate any stenosis in the participants’ left main coronary artery (LCA). Therefore, these results do not align with the findings of the current study.

Sex differences in chest pain findings

The results of the present study showed that the mean intensity pain score in men was slightly higher than in women, although it did not have statistical significance. Additionally, although more men reported their pain as squeezing, no significant qualitative difference in pain quality between men and women was observed. Based on these findings, 69% of individuals reported chest pain in the centre of the chest. Furthermore, women complained more about pain on the left side of the chest than men. Bosner et al. (2009) and the American Heart Association (AHA) also reported similar results to those of the present study29,30.

Moreover, the results indicated that the duration of chest pain, whether longer or shorter than 10 min, was more common in men. However, the results showed that 67.7% of both men and women who had chest pain lasting less than 10 min also experienced a heart attack. Therefore, the findings suggest that even short episodes of chest pain in patients with myocardial infarction may have clinical significance and warrant careful evaluation. The AHA and the Centres for Disease Control and Prevention (CDC) have not specified a precise duration for chest pain in their latest reports for diagnosing a heart attack30,31. These findings can corroborate the findings of the present study. This is in contrast to various past sources that have reported different timeframes as indicators of heart attack-related chest pain32.

The results of the present study demonstrated that chest pain exacerbated with exercise in individuals, which was an unexpected finding. Considering that the heart receives signals from the brain during exercise or intense physical activity to work harder to provide more blood supply to the body, it means that the heart works more vigorously and beats harder. In the case of any obstruction in the coronary arteries, blood vessels cannot expand properly, and coronary blood supply decreases33. Bosner et al. (2009) also reported that pain intensified in individuals with exercise29.

Furthermore, the results of the present study showed that dizziness was significantly more common in women than in men. Similar studies have also reported that women often exhibit more atypical symptoms compared to men, including symptoms like dizziness, nausea, vomiting, sweating, and fear of death34,35,36. Although one study found no significant difference in atypical symptoms of chest pain related to heart attack between men and women29.

Relationship between demographic characteristics and coronary artery occlusions

The results of the present study indicated that among patients with confirmed myocardial infarction, being married was associated with a higher frequency of LAD occlusion. In contrast, a systematic review and meta-analysis by Wong et al. (2018)37, which included more than two million participants from 16 countries, reported that being unmarried was associated with an increased risk of cardiovascular events. However, differences in study design (cross-sectional in the present study versus prospective in the mentioned meta-analysis) and population characteristics may account for this inconsistency. Furthermore, marital stress and other psychosocial factors, such as financial or occupational stress, might influence this association and should be considered in future research.

The present study also showed that the highest prevalence of myocardial infarction occurred among individuals with blood group A negative, while the lowest prevalence was observed in those with blood group O positive. This finding is partly consistent with the results of Groot et al. (2020)38, who found that individuals with blood groups A or B had an 8% higher risk of myocardial infarction and a 10% higher risk of heart failure compared to those with blood group O. Nevertheless, due to the cross-sectional design of the present study, causal interpretations should be avoided, and further longitudinal research is warranted to confirm these associations.

Moreover, individuals with a positive family history of heart disease were more likely to have LAD and LCX occlusions. Interestingly, 36% of male and 34% of female patients with myocardial infarction in this study had no family history of heart disease, suggesting that other environmental and genetic factors also play a role. The present study found that most patients reported a maternal history of heart disease. This observation may be related to the potential contribution of mitochondrial DNA (mtDNA) mutations, which follow a maternal inheritance pattern. Dabravolski et al. (2022)39 highlighted the role of mtDNA mutations in cardiovascular disease, which may provide a possible biological explanation for our findings. However, this hypothesis requires confirmation through future genetic and molecular studies.

Clinical Implications

The findings of this study indicate that among patients with confirmed myocardial infarction, stenosis in smaller coronary vessels, particularly the Mid-LCX, was more prevalent in women. These results contribute to a better understanding of gender-related differences in angiographic patterns among MI patients. Despite the higher prevalence of Mid-LCX stenosis in women, most typical features of chest pain were similar between the two genders, emphasizing the need for comprehensive and unbiased clinical assessments for all patients. It should be noted that the results of this study are specific to patients with myocardial infarction and cannot be generalized to all individuals presenting with chest pain or suspected coronary artery disease. Therefore, caution should be exercised when interpreting these findings beyond this population. Future studies including all patients presenting with angina are recommended to further explore sex-related predictors of myocardial infarction and to examine the clinical presentation of coronary artery disease in broader and more diverse populations. Such research could provide valuable insights for improving early diagnosis, targeted intervention, and patient-centred management strategies.

Strengths, limitations and suggestions

The present study provides a comprehensive examination of differences in angiographic findings between men and women, as well as chest pain symptoms and characteristics. This can lead to more gender-specific treatment approaches. Furthermore, it offers extensive information on the relationship between demographic characteristics and chest pain symptoms with coronary artery occlusions. Among the limitations of the current study is the lack of assessment of recent stress-inducing factors, marital relationships, and the onset of menopause, including early menopause. Additionally, this study was conducted in the population of southern Iran. Therefore, caution should be exercised when generalizing these results to other cultures and ethnicities. A major limitation of this study is that only patients with confirmed myocardial infarction were included. Therefore, the findings cannot be generalized to all patients presenting with chest pain or suspected coronary artery disease. Additionally, Table 1 presents the distribution of patients’ blood groups; however, data on blood group distribution in the reference population were not available, and therefore, the observed differences in patients cannot be definitively compared with the general population.

It is recommended that future studies consider assessing recent stress-inducing factors, marital relationships, and the timing of menopause, including early menopause. Additionally, to enhance the generalizability of findings, future studies should include a more diverse population. This may involve conducting research in various regions, cultures, and ethnicities to better understand the diversity in cardiovascular health factors. Furthermore, conducting multi-centre studies involving different geographical locations and populations can contribute to validating and expanding the current study’s findings. Future studies should include all patients presenting with angina to better assess sex-specific predictors of myocardial infarction. In future studies, it is suggested that conducting longitudinal research can provide valuable insights into the temporal relationships between risk factors, coronary stenosis, and clinical symptoms. This approach would allow researchers to observe changes over time and report potential causal relationships. Considering the observed association with blood groups A and B, future studies could investigate in more detail the relationship between specific blood groups and coronary manifestations. Additionally, delving into the underlying mechanisms that contribute to this association would be beneficial.

Conclusion

The present study demonstrated that stenosis in small coronary vessels such as Mid-LCX was more prevalent in women than in men. On the other hand, no significant and notable differences were observed between men and women in other angiography findings, although stenosis in Total LAD, Total LCX, and Total RCA was higher in women. Furthermore, the current study revealed that most typical features of chest pain were similar between men and women, with no significant differences. The results of this study emphasize the importance of considering the origin and nature of chest pain in all its forms, regardless of the duration of pain. Additionally, individuals with blood groups A and B and a family history of heart disease on the maternal side exhibited the highest manifestations during heart attacks. Moreover, the present study indicated that stenosis in LAD has a broader range of clinical symptoms and is associated with more severe pain. Symptoms such as fatigue and shortness of breath during activity, increased pain when climbing stairs or even walking on flat ground, are more common in individuals with LAD stenosis. Symptoms such as chest pain accompanied by shortness of breath, increased pain when walking on a flat surface, and pain relief with rest are more prevalent in individuals with LCX stenosis. Fatigue and increased pain when walking on a flat surface are also more common in RCA stenosis. The results highlight gender differences in stenosis patterns among MI patients, but further research is needed to confirm these patterns in broader populations including all patients presenting with chest pain.