European Journal of Cardiovascular Medicine

Organophosphate (OP) pesticides are the most extensively used insecticides, particularly in rural or undeveloped parts of developing countries.¹ Approximately two hundred thousand persons die from OP pesticide poisoning annually, and the rate of mortality is generally greater than 15%.² These pesticides are progressively used as suicide substance with an increasing rate of mortality during the recent years.³

The cardiac manifestations of OPs poisoning occur in a majority of affected patients and may range from harmless electrocardiographic (ECG) changes such as sinus tachycardia, to life-threatening complications such as cardiogenic pulmonary edema.⁴ Additionally, OPs poisoning leads to atrioventricular (AV) node blockade, alterations in ST segment, prolongation of QT interval, alterations in P wave, lethal arrhythmias, and cardiac arrest through the inhibition of acetylcholinesterase and consequently increased synaptic accumulation of free acetylcholine level.^5,6 The most fatality of OP poisoning results from respiratory failure.⁷

The clinical manifestations of damage caused by OPs pesticides to the myocardium vary among patients, which include heart failure, cardiogenic shock, arrhythmia, and sudden death. Present study was conducted to estimate the cardiovascular complications and in hospital outcomes in patients of organophosphorus compound poisoning in tertiary care hospital.

Present study was prospective, observational study, conducted in department of general medicine, at Tertiary Care Teaching Hospital. Study period was from May 2022 To August 2024. Study was approved by institutional ethical committee.

Inclusion criteria

All patients of more 18 years, presenting with history of exposure to and signs and symptoms of organophosphorus compound poisoning and documentary evidence of organophosphorus compound admitted in ICU/MICU/Medicine ward, willing to participate in present study

Exclusion criteria

• Age < 18 years
• Preexisting cardiovascular (coronary artery disease, systemic hypertension, peripheral arterial diseases, rheumatic heart diseases, congenital heart diseases, cardiomyopathies etc)
• Concomitant exposure to other poisoning agents/compounds

Study was explained to participants in local language & written informed consent was taken. The data and information pertaining to the cases were collected and recorded on a proforma. Wherever possible the attendants of the patient was asked to get the package or the package insert of the poison to confirm the compound , history and examination findings at the time of presentation after poisoning was noted.

A complete Hemogram, renal function tests, liver function tests, serum choline esterase, ECG and 2d echo if required was done for all the patients. ECG analysis included the rate, rhythm, ST-T abnormalities, conduction defects, and measurement of PR and QT intervals, ventricular extrasystole, atrial extra systole, Inversion, polymorphic ventricular tachycardia and ventricular fibrillation. The QT intervals was measured from the first deflection of the QRS complex to the point of T-wave offset, defined as the return of the T wave to baseline of the 12-lead ECG. If a U wave was present, the T wave offset was defined as the nadir of the curve between the T and U waves. The QT interval was corrected according to the formula of Bazett. QTc was considered prolonged when it was longer than 0.41 s in men and longer than 0.42 s in women.

Details of treatment given was recorded. Cardiovascular complications were noted to look for is sinus tachycardia, sinus bradycardia, hypertension, hypotension, pulmonary edema (cardiogenic). Patient was classified according to paradenia score of op compound consumption.

The data are tabulated in Microsoft excel and analyzed with SPSS V.24 software. The continuous variables are presented with mean and standard deviation. The categorical variables are presented with frequency and percentage. The results are presented with appropriate tables and diagrams. Chi square test is used for the statistical analysis. The p value ≤0.05 is considered statistically significant.

Among, 150 patients, majority were from the 21-40 years age group (50.7%), followed by 41-60 years age group (38.7%). Majority of the participants are male, comprising 85.3% of the sample, while females represent only 14.7%. 4.6% of patients had psychiatric illnesses, while smaller percentages had diabetes mellitus (2.0%) and bronchial asthma (0.7%).

Table 1: General characteristics

Chlorpyrifos is the most commonly consumed compound ((27.3%), and monocrotophos (11.3 %). A significant proportion of the sample (34.0%) consumed more than 150 ml of OP compounds. Majority of cases (90.0%) were suicidal in nature, while 10.0% were due to accidental poisoning. Most patients (52.0%) presented between 6-12 hours after ingestion.

Table 2: OP compound characteristics

Most common symptom was excessive salivation (75.3 %), followed by sweating (66.0%), lacrimation (55.3%), vomiting (22.7%), loose stools (18.7%), bronchorrhea (19.3%), muscle cramps (16.0%), weakness (16.0%), fasciculation (16.0%), meiosis (32.0%), altered sensation (4.0%) & seizures (1.3 %).

Table 3: Symptoms

Mean pulse rate was 94.66±22.81 beats per minute, respiratory rate was 18.34±4.21 breaths per minute, systolic blood pressure (SBP) was 114.67±21.76 mmHg, diastolic blood pressure (DBP) was 73.27±11.84 mmHg, and oxygen saturation (SPO2) was 96.29±4.21%. Mean white blood cell (WBC) count was 6.89±3.86 (*1000 per μl), and the mean serum cholinesterase level was 1469.39±1433.22 IU/L.

Table 4. Distribution of hemodynamic & blood parameters

At admission, the majority (74.6%) had normal sinus rhythm. However, 20.6 % had sinus tachycardia, while smaller proportions experienced sinus bradycardia (0.6 %), ST depression (3.3%), and ST elevation (0.7%). During hospitalization common ECG changes were QTC prolongation (6 %). ventricular premature beats (3.3%), ST depression (2.7%), and first-degree heart block (1.3%).

Table 5: ECG changes

2D echo findings shows that 52.7% of patients did not undergo the test. Among those tested, 39.3% had normal findings, while 6.7% had global left ventricular (LV) hypokinesia and 1.3% had anterior wall hypokinesia.

Table 6: Distribution of 2D echo

Cardiovascular complications reveals that 20.7% of patients experienced sinus tachycardia. Hypotension (8.0%), cardiac failure (6.7%), and type 2 myocardial infarction (6.0%) were also notable. Other complications such as QTC prolongation (5.3%) and sinus bradycardia (0.7%) were less common.

Table 7: Distribution of Cardiovascular complications

Other complications noted were respiratory failure (12.7%), sepsis (12 %), ventilator-associated pneumonia (8 %) and intermediate syndrome (5.3%). 12.7% of patients required mechanical ventilation, while 87.3% did not.

Table 8: Distribution of Other complications

According to, Peradeniya score 30.7% of patients scored 2, while 24.0% had a score of 6. Lower scores (1, 4) and higher scores (7, 8, 9) were less frequent. 50.7% of patients had mild poisoning, while 46.7% had moderate poisoning. Severe poisoning occurred in 2.7% of cases.

Table 9: Peradeniya score & Severity of poisoning

Mean total atropine administered was 73.56±11.24 mg, and the mean total pralidoxime (PAM) given was 18.40±2.22 g. Mean duration of stay in the ward was 9.53±3.65 days, while the mean stay in the ICU was 2.66±2.32 days.

Table 10: Distribution of treatment given & duration of stay

In-hospital outcomes reveals that 12.0% of patients died, while the majority (88.0%) were discharged.

Table 11: Distribution of In hospital outcomes

The association of cardiac failure hypertension and STEMI are statistically significant with level of serum cholinesterase.

Table 12: Association of Cardiovascular complications with level of serum cholinesterase

The association of hypotension VPCs and type 2 MI are statistically significant with Peradeniya score.

Table 13: Association of Cardiovascular complications with Peradeniya score

Level of serum cholinesterase. The association is not statistically significant with in-hospital outcomes.

Table 14: Association of in-hospital outcomes with level of serum cholinesterase

Association of in-hospital outcomes with Peradeniya score was statistically significant .

Table 15: Association of in-hospital outcomes with Peradeniya score

Organophosphorus (OP) compound poisoning is a major global health issue, particularly in developing countries such as India, where agricultural practices heavily rely on the use of pesticides. The accessibility and widespread use of these toxic compounds have led to a rise in accidental and intentional poisonings, making OP toxicity a common reason for emergency hospital admissions.

While the acute neurotoxic effects of OP poisoning are well-documented, there is growing recognition of cardiovascular complications as a critical factor influencing patient outcomes. These complications, which include arrhythmias, conduction abnormalities, hypotension, and even myocardial injury, may significantly increase the risk of mortality, especially during the acute phase of poisoning.⁷

The cardiovascular system's response to OP poisoning can be unpredictable, and the underlying mechanisms are not fully understood. Possible explanations include direct toxic effects of OP compounds on the heart, disruption of autonomic regulation, electrolyte imbalances, and hypoxia due to respiratory failure. These factors can lead to life-threatening conditions such as ventricular tachycardia, atrioventricular blocks, and sudden cardiac arrest. Understanding the prevalence and nature of these cardiovascular events in OP poisoning is essential for improving clinical outcomes and guiding the management of such patients.⁸

86. Laudari et al.,⁹ noted that, most of the patients belonged to the population of active productive age group (86.9% were between 15 and 45 years of age). Women constituted 59.1% of the cases. Banday et al.,¹⁰ stated that, one hundred two (76.7%) were males and 31 (23.3%) female. Most of the cases were young people 80% (< 40years) predominantly males. There was wide variation in age ranging from a minimum of 13-68 years with mean age of 31.5 years. Similar findings were noted in present study.

In our study, chlorpyrifos (38 %) was the most commonly consumed compound followed by profenofos (27.3%) and monocrotophos (11 %). S. Laudari et al.,⁹ stated that, the most common OP compound consumed was chlorpyrifos plus cypermethrin (70%). Sanket Makwana et al.,¹¹ stated that, methyl parathion was the most common organophosphate compound consumed comprising 20% of the cases; in their study, they were not able to find out OP compound in 23(46%) patients either due to patient not given proper history related OP compound or not brought the OP sample.⁷¹

Most common symptom was excessive salivation (75.3 %), followed by sweating (66.0%), lacrimation (55.3%), vomiting (22.7%), loose stools (18.7%), bronchorrhea (19.3%), muscle cramps (16.0%), weakness (16.0%), fasciculation (16.0%), meiosis (32.0%), altered sensation (4.0%) & seizures (1.3 %).

Ghulam Hussain Balouch et al.,¹² stated that, regarding clinical manifestation, salivation (92%) was most common followed by lacrimation (86%), urination (55%), diarrhea (52%), GI upset (71%), emesis (92%), diaphoresis (69%), miosis (90%), bronchospasm (37%), bronchorrhea (40%), muscle fasciculations (71%), cramping and weakness (75%), restlessness (80%), confusion (83%), ataxia (34%), tremors (46%), seizures (43%) and coma (66%) patients.

Sangita D et al.,¹³ stated that, the commonest symptom noted was vomiting (94%), followed by excessive secretions (84%). Seventy percent of the patients had breathlessness, and 28% of the patients had diarrhea. Altered levels of consciousness and seizures were relatively uncommon presentations and were reported by 22% and 12% of the patients, respectively. In the study by Chintale KN et al.,¹⁴ the commonest physical finding was miosis, found in 71.3% of the patients similar to that found in our study (57%). Whereas fasciculations were more common in the study by Chintale KN et al.,¹⁴ (63.23%).

49. Laudari et al.,⁹ stated that, the most common cardiac sign was sinus tachycardia (49.6%) followed by pulmonary edema (20.9%). The most common ECG abnormality was QTc prolongation (18.3%) followed by ventricular extrasystole (12.2%). ST elevation/depression and isolated T inversion mostly in anteroseptal leads were noticed in 8.7% of patients. Majority of these patients were elderly with documented hypokalemia (40.9%), mixed acidosis (6.1%) and non-cardiogenic pulmonary edema (18.3%).⁶⁸ Sanket Makwana et al.,¹¹ stated that, most common ECG abnormality was Sinus Tachycardia in 12(24%) followed by ST-T changes 8(16%), QTc prolongation in 6(12%), Sinus Bradycardia 4(8%), Extrasystole 2(4%), PR Prolongation 1(2%), AF 1(2%) and VT 1(2%).⁷¹ Similar findings were noted in present study.

In our study, the distribution of the Peradeniya score reveals that 30.7% of patients scored 2, while 24.0% had a score of 6. Lower scores (1, 4) and higher scores (7, 8, 9) were less frequent. Sangita D et al.,¹³ stated that, Using the POP scale, 18% of the patients had a POP scale score of 10, and 12% had a score of 5. A POPS score of 3 and 4 was present in 8% each of the patients. Two patients had a POPS score of 0, whereas four patients had a full score of 11. According to the severity of poisoning using POPS score, 36% of the patients had severe poisoning, whereas 27% had mild poisoning, and 37% of the patients had moderate poisoning.⁷⁶

Sangita D et al.,¹³ stated that, only 11.11% of the patients with mild poisoning needed ventilatory support, whereas 16.2% of patients with moderate poisoning and 100% of patients with a severe grade of poisoning required ventilator assistance. Of the 100 patients enrolled in the study, 78 patients (78%) improved. The overall mortality in their study was 22%. The mean duration of ICU stay was <7 days in 24 (88.9%) out of 27 mild cases, 7 (18.9%) of 37 moderate cases, and one of 36 (2.9%) severe cases, whereas 3 (11.1%) of the 27 mild cases, 30 (81.8%) of the 37 cases, and 35 (97.2%) of the 36 severe cases required ICU stay of >7 days.

Serum cholinesterase levels were significantly associated with cardiovascular complications , since all the patients who developed cardiac failure(6.7%) was having serum cholinesterase below 4000 IU . Among those patients who developed ST elevation MI 28.6% of the patients was having serum cholinesterase more than 4000 IU. Based on severity of poising according to Peradeniya score hypertension and VPCs were more prevalent in severe poisoning and Type 2 MI was more prevalent in patient who were under mild poisoning.

Jayshree Gamit et al.,¹⁵ stated that, there was no statistically significant association between age and QTc interval prolongation, as well as gender and QTc interval prolongation. A 15 (25%) patients presented 6 hours after exposure to OP compound and amongst them QTc prolongation was seen in 14 (93.33%) patients, only 15.56% patients had QTc prolongation amongst 45 patients who presented within 6 hours of exposure (p-value <0.0001). Shahsavari Nia et al.,¹⁶ stated that, there was a significant correlation between ST segment alterations and poisoning outcomes including morbidity and death (P=0.02). ST segment changes were seen in 4 patients. Among patients, 2% had PR interval greater than 0.21s (0.08-0.24s) and 3% had QT interval longer than 0.45s (0.2-0.48).⁷⁷

In spite of every sincere effort the present study has lacunae. The notable short comings of this study were sample size was small, single center study, was carried out in a tertiary care hospital, so hospital bias cannot be ruled out. Some patients were referred from other hospitals , so treatment from referred hospital (e.g.- atropine) may influence the cardiovascular findings.

Further research is warranted to explore the underlying mechanisms of cardiovascular dysfunction in OP poisoning and to develop targeted therapeutic interventions that can mitigate the cardiovascular risks and improve overall outcomes in these patients.

The findings from this study underscore the need for early recognition and aggressive management of cardiovascular symptoms, including cardiac failure hypotension, tachyarrhythmias myocardial infarction and conduction abnormalities, in patients presenting with OP poisoning. In-hospital outcomes were strongly influenced by the presence and severity of cardiovascular complications, suggesting that improved monitoring and timely interventions in these patients could lead to better prognoses.

The study emphasizes the importance of incorporating routine cardiovascular assessments, such as electrocardiography (ECG) and continuous hemodynamic monitoring, into the management protocols for OP poisoning, especially in resource-limited settings like rural India.

Conflict of Interest: None to declare

Source of funding: Nil

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