European Journal of Cardiovascular Medicine

Bee stings are a frequently encountered environmental hazard, particularly in rural parts of India, where people are often exposed to agricultural and outdoor activities. While most stings result in minor local reactions such as pain, erythema, or swelling, a significant number of cases can progress to systemic manifestations, ranging from generalized urticaria to life-threatening anaphylactic shock[1,2]. However, one of the most under-recognized complications in such patients is myocardial injury, which can have profound clinical implications if not promptly identified and managed[3].

The cardiovascular system is highly susceptible to the effects of bee venom, which contains a complex mix of biologically active components, including melittin, apamin, phospholipase A2, hyaluronidase, and histamine[4,5]. These constituents exert a combination of direct toxic effects on cardiac myocytes and trigger severe immune and inflammatory responses, particularly in individuals with hypersensitivity to these agents. This cascade may lead to coronary artery vasospasm, increased vascular permeability, platelet aggregation, and cytokine release, culminating in various forms of cardiac injury[6]. In more severe cases, these reactions may result in acute coronary syndromes, such as Kounis syndrome, a form of allergic myocardial infarction resulting from mast cell degranulation and the release of vasoactive mediators[7,8].

Clinically, patients may present with a range of cardiovascular abnormalities, including chest pain, palpitations, hypotension, and syncope, often within minutes to hours after the sting[9]. Electrocardiographic abnormalities are highly variable and may include ST-segment elevation or depression, T-wave inversion, pathological Q waves, and conduction block[10]. Additionally, rhythm disturbances, such as supraventricular arrhythmias, ventricular ectopics, junctional rhythms, and right bundle branch block, have been documented in the literature[11,12]. Importantly, these changes may occur even in patients who do not exhibit severe allergic reactions, making cardiac evaluation imperative, regardless of the initial systemic symptoms.

Source of data

The study was carried out on patients who were admitted with history of bee sting presenting within 24 hours in the Department of General Medicine at Hassan Institute of Medical Science after meeting inclusion and exclusion criteria from  march 2024 to february 2025.

Study design

Hospital based Longitudinal Cross Sectional Study.

Study period: 1 year

Inclusion criteria

·         Patients who are more than 18 years of age.

·         Patients with history of bee sting presenting within 24 hours with or without co-morbidity.

·         Patients who are willing to participate in the study.

Exclusion criteria

·         Age less than 18 years.

·         Pregnant or lactating women with bee sting.

·         Patients with history of ischaemic heart disease.

·         Patients who are not willing to participate in the study.

Methodology

Patients fulfilling the inclusion criteria were recruited into the study. The aims and objectives of the intended study was explained to the subjects and informed written consent was taken. Data was collected as per the proforma sheet.Complete history, physical examination, local examination and 12 lead ECG and Echocardiography was performedon every subjects participating in the study as per predefined proforma, To estimate Serum high sensitivity Troponin I and CK-MB levels blood samples were taken for all the patients with in 6 hours of admission.

Serum high sensitive Troponin-I  and CK-MB level was tested in biochemistry lab Hims, Hassan using ‘architect stat’ (registered) and multigent CK-MB(registered) equipment respectively, architect stat is chemiluminescent  microparticle immunoassay(CMIA) with architect stat High Sensitive Troponin-I 3P25 as a reagent and multigent CK-MB assay uses the immunoinhibition method to measure the catalytic activity of the CKMB isoenzyme with 6K25-30 multigent CK-MB as a reagent.

The biological reference value for serum high sensitive Troponin-I was taken to be 0-34.2 pg/ml in males and 0-15.6 pg/ml in females and the biological reference value for CK-MB was taken to be 5-25 IU/L based on the evidence from the existing literature.

The outcome of all the patients was documented and the incidence of myocardial injury and ECG abnormalities was analysed and results were published

Statistical Analysis

The data collected was entered in a MS EXCEL sheet and analysed using SPSS trial version 28 and categorical data will be expected in percentage and proportion, Continuous data was expressed in mean and standard deviation. Association between categorical variables was tested using chi-square test of association.

Table 1: Distribution of participants according to age

The age distribution of patients within the study population, categorized into 10-year intervals from 10 to 79 years, showed that the majority of patients were in the 30–39 age group (24.36%), followed closely by the 20–29 age group (23.08%). The 40–49 (21.79%) and 50–59 (20.51%) age groups also contributed substantially to the study population.

A smaller proportion of patients were observed in the 60–69 age group (9.62%), while the 10–19 age group accounted for only 0.64% of the participants. No patients were recorded in the 70–79 age group (0%). Overall, the distribution indicates that most participants were concentrated in the third to fifth decades of life.

Table 2: Clinical Presentation and Symptom Profile of Study Participants

Chest pain was present in 49 (31.4%) participants, while 107 (68.6%) did not report chest pain. Vomiting and shortness of breath were observed in 2 (1.3%) participants each. Sweating was not reported in any participant (100% absence). Palpitations were present in 29 (18.6%) participants, and giddiness was reported by 4 (2.6%). Local swelling or pain was present in 150 (96.1%) participants. Overall, chest pain and local swelling were the most commonly reported symptoms.

Table 3: Distribution of Electrocardiographic (ECG) Findings Among Study Participants

Normal ECG findings were observed in 50 (32.1%) participants, while 106 (67.9%) had abnormal ECG findings. ST depression was seen in 27 (17.3%), ventricular premature complexes (VPCs) in 24 (15.3%), T-wave inversion in 21 (13.4%), and ST elevation in 12 (7.7%) participants. Right bundle branch block (RBBB) was identified in 10 (6.4%) participants. Supraventricular tachycardia (0.6%) and junctional rhythm (0.6%) were rare findings, while atrial fibrillation was present in 4 (2.5%) participants.

Table 4: Echocardiographic Findings  Distribution

On echocardiographic evaluation, 140 (89.7%) participants had normal findings. Regional wall motion abnormality (RWMA) was noted in 16 (10.2%). Overall, the majority of participants had normal echocardiographic findings.

Table 5: ICU Requirement Distribution

Most participants, 133 (85.2%), did not require ICU admission. ICU admission was required in 23 (14.7%) participants. Thus, the majority were managed without intensive care.

Table 6: Descriptive Statistics of Clinical and Biochemical Parameters

The mean number of stings was 55.99 ± 31.88, ranging from 13 to 150. The average time from bite to hospitalization was 3.62 ± 1.51 hours. The mean systolic blood pressure was 138.37 ± 18.40 mmHg, and the mean diastolic blood pressure was 85.18 ± 11.31 mmHg. The mean pulse rate was 104.42 ± 12.79 beats per minute, and the mean respiratory rate was 19.83 ± 3.15 breaths per minute. The mean Troponin-I level was 31.44 ± 33.50, and the mean CK-MB level was 23.27 ± 17.84. The average hospital stay was 2.58 ± 1.81 days, ranging from 1 to 7 days.

In this study, the majority of participants belonged to the 30–39 years age group (24.36%), followed closely by the 20–29 years group (23.08%). The 40–49 (21.79%) and 50–59 (20.51%) age groups also contributed significantly. Only a small proportion were aged 60–69 years (9.62%), and very few were in the 10–19 age group (0.64%), with no participants above 70 years[13].

This distribution indicates that bee sting exposure is more common in the active working-age population, likely due to increased outdoor exposure and occupational risks. Similar patterns have been reported in previous studies where younger and middle-aged adults are more frequently affected due to environmental exposure[14].

Chest pain (31.4%) and local swelling or pain (96.1%) were the most common presenting symptoms. Palpitations were noted in 18.6% of participants, while giddiness, vomiting, and shortness of breath were relatively rare. The high prevalence of local reactions reflects the direct toxic and inflammatory effects of venom, whereas cardiac-related symptoms such as chest pain and palpitations indicate possible systemic involvement.

Abnormal ECG findings were observed in 67.9% of participants, indicating a high prevalence of cardiac involvement. The most common abnormalities included ST depression (17.3%), VPCs (15.3%), and T-wave inversion (13.4%). ST elevation (7.7%) and left bundle branch block (6.4%) were less frequent, while arrhythmias such as atrial fibrillation and supraventricular tachycardia were rare[15].

Significant associations were observed between diabetes and ECG abnormalities, particularly ST depression, VPCs, and T-wave inversion. Similarly, hypertension showed strong associations with these ECG changes. Dyslipidemia was significantly associated with ST elevation, although the small sample size limits interpretation. No significant association was found with hypothyroidism, likely due to the very low number of cases.

These findings suggest that bee venom may precipitate myocardial ischemia or electrical instability, especially in individuals with pre-existing cardiovascular risk factors.

The majority of participants (89.7%) had normal echocardiographic findings, while regional wall motion abnormalities (RWMA) were observed in 10.2%. However, a significant association was found between RWMA and both diabetes and hypertension[16].

Among diabetic patients, RWMA was present in 25.6% compared to only 4.4% in non-diabetics. Similarly, hypertensive patients showed a higher prevalence of RWMA (33.3%) compared to non-hypertensive individuals (3.3%). These findings indicate that underlying comorbidities significantly increase the risk of myocardial dysfunction following envenomation

A key observation of this study is the strong association between comorbidities, particularly diabetes mellitus and hypertension, with both ECG abnormalities and echocardiographic changes such as regional wall motion abnormalities. These findings indicate that patients with underlying metabolic and vascular disorders are more susceptible to myocardial dysfunction following bee sting envenomation.

Despite the presence of cardiac abnormalities, the overall prognosis was excellent, with no mortality and all patients achieving favorable outcomes. This underscores the effectiveness of early recognition, prompt supportive care, and appropriate monitoring in the management of such cases.

Overall, this study underscores the importance of routine cardiac assessment, including ECG and echocardiography, in patients with multiple bee stings, particularly those with pre-existing comorbidities. It also highlights the need for heightened clinical awareness regarding potential cardiovascular complications.

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