European Journal of Cardiovascular Medicine

Myocardial infarction (MI) results from sudden obstruction of the blood flow to a portion of the heart muscle, typically due to a thrombotic blockage following rupture of an atherosclerotic plaque within the coronary arteries. This leads to myocardial ischemia, and if not promptly addressed, causes irreversible myocardial cell death. The epidemiological burden is intensified by lifestyle-related risk factors such as unhealthy dietary patterns, sedentary behavior, tobacco use, rising prevalence of obesity, and poor control of metabolic disorders like diabetes and hypertension. These factors contribute both to the development of atherosclerosis and to poor outcomes following infarction (1).

In addition to atherosclerotic plaque rupture, other causes include coronary artery spasms, embolic occlusions, spontaneous coronary artery dissections, and severe hypoxic states like profound anemia. Typical clinical presentation involves intense chest pain described as pressure or squeezing, which may radiate to the arm, neck, jaw, or back, and is often accompanied by shortness of breath, diaphoresis, nausea, and dizziness. Patients with diabetes may exhibit atypical or even silent presentations, with complaints such as fatigue, mild epigastric discomfort, or no symptoms at all, leading to potential delays in diagnosis (2).

Diagnosis of MI relies on clinical history, electrocardiogram (ECG), and biochemical markers (Trop I and CPK-MB). Imaging modalities such as echocardiography can assess wall motion abnormalities, and coronary angiography helps localize the occlusion and guide therapeutic intervention (Per-cutaneous interventions). Pharmacologic therapy includes antiplatelet agents like aspirin, clopidogrel, ticagrelor, anticoagulants, thrombolytics, beta-blockers, ACE inhibitors, and statins. In patients with significant coronary occlusion and multiple vessel involvement, coronary artery bypass grafting may be required to reestablish blood flow (3).

Despite optimal treatment, MI carries a risk of severe complications, among which cardiac arrhythmias are particularly significant. These rhythm disturbances commonly occur in the acute setting and can rapidly become fatal. The early detection and real-time management of these events significantly improve survival rates and reduce complications (4).

Furthermore, the identification of arrhythmias during the acute phase of MI offers valuable prognostic information. Persistent or recurrent arrhythmias may indicate larger infarct size, ongoing myocardial instability, or the presence of an arrhythmogenic substrate and, in some cases, the use of implantable cardioverter-defibrillators. These observations underscore the importance of continuous telemetry and rhythm surveillance in coronary care units, particularly within the initial 24-hour window, which represents the period of highest vulnerability (5).

This prospective observational study was conducted at the Department of Medicine, Rajshree Medical Research Institute, Bareilly, from August 2023 to July 2024, after receiving ethical clearance. It aimed to evaluate the prevalence, types, and outcomes of arrhythmias occurring within 24 hours of myocardial infarction using systematic ECG monitoring and standardized criteria. Patients aged 18 years and above with confirmed acute MI presenting within 24 hours of symptom onset were included. Exclusion criteria comprised prior ST-Elevation MI, existing arrhythmias, cardiac devices, terminal illness, or pregnancy. Informed consent was obtained, and confidentiality was maintained as per ethical guidelines.

Ethical Considerations and Confidentiality:

Ethical approval for this study was provided by the Institutional Ethical Committee , and informed consent was obtained from each of the study participants. Participants were allowed to withdraw their names at any given time during the course of the study. Confidentiality of all the data was ensured by keeping the responses anonymous.

In this study of 100 myocardial infarction patients, overall mortality was 3%, with death incidence in the 61–70 years age group. Males outnumbered females (63 vs. 37), but gender had no statistically significant impact on outcome. Rhythm analysis showed sinus rhythm as the most common (44%), followed by sinus bradycardia and bundle branch blocks. No statistically significant correlation was found between age groups and arrhythmia types, indicating rhythm distribution was relatively uniform across age categories.

Table 1: Distribution of Outcomes across Rhythm

Out of 100 patients, 97% showed clinical improvement, while only 3% died. Mortality was observed in BFB, LBBB, and ST (Table 1).

Table 2: Distribution of Outcomes Based on ECG Localization

Anterior wall myocardial infarction (AWMI) was the most common (50% of cases) with a mortality rate of 2.0%. Mortality was highest in lateral wall myocardial infarction (LWMI) at 14.3%, with the rest showing no deaths (Table 2).

Table 3: Distribution of ECG LOCALIZATION across Rhythm

The statistical analysis highlights a strong association between specific arrhythmic patterns and the localization of infarction, as demonstrated by the Chi-Square test statistic (156.2883) with a p-value of 0.0000, indicating a highly significant correlation. The most common rhythm observed was sinus rhythm, followed by notable occurrences of ventricular tachycardia   , atrial fibrillation, and bundle branch blocks (BFB, LBBB, RBBB). Interestingly, certain arrhythmias were exclusively associated with particular infarct locations; for example, AFIB was observed only in extensive wall MI, whereas sinus bradycardia was predominant in inferior wall MI (IWMI). These variations suggest that the site of myocardial injury plays a crucial role in determining the type of electrical disturbances that occur during the acute phase of MI.

The presence of bundle branch blocks (BFB, LBBB, RBBB) and complete heart block (CHB) indicates conduction system compromise, which may necessitate temporary or permanent pacemaker implantation. Furthermore, life-threatening arrhythmias like ventricular premature contractions (VPC) and ventricular tachycardia    were observed in a subset of patients, reinforcing the need for continuous cardiac monitoring and prompt antiarrhythmic therapy in the first 24 hours of hospitalization

In the present study, most patients across all age groups showed clinical improvement with low mortality, the highest being 9.1% in the 61–70 age group. In the present study, males (98.4%) and females (94.6%) showed high improvement rates post-MI, with no significant sex-based outcome, aligning with Campbell RW et al. (1981) (6). Unstable blood pressure strongly correlated with AFib and VT (p = 0.0000), as supported by Majid A et al. (2018) (7). ECG localization significantly influenced arrhythmic patterns, with anterior wall MI linked to sinus rhythm and posterior wall MI to atrial fibrillation, aligning with Ohlow MA et al. (2012), who emphasized early ECG in arrhythmia prediction post-MI (8). Most patients across different arrhythmias had favorable outcomes, with a low overall mortality of 3%. AFIB, LBBB, and SR patients had a 100% improvement rate, though rhythm type was not significantly associated with mortality. These findings are in line with Kuchar DL et al. (1986), who observed high survival in common arrhythmias post-MI, despite their influence on recovery duration (9). Similarly, ECG localization showed no significant link with outcomes, supporting Demidova MM et al. (2012), who emphasized arrhythmia type over infarct site in determining early MI prognosis (10).

This study titled “Arrhythmias in Myocardial Infarct Patients in First 24 Hours in Tertiary Care Hospital” was conducted at Rajshree Medical Research Institute from August 2023 to July 2024 on 100 patients with acute myocardial infarction. It assessed arrhythmia prevalence, types, and prognostic implications in the first 24 hours. Sinus rhythm was most common (44%), with VT and AFIB observed in 4% each. AWMI (50%) was most frequent. Mortality was 3%. There was strong association between specific arrhythmic patterns and the localization of infarction. Blood pressure instability was frequent in ventricular tachycardia.

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