Inferior myocardial infarctions are generally considered to carry a better prognosis than anterior wall infarctions. Several recent trials evaluating thrombolytic therapy in acute inferior wall infarction appear to support this perception, reporting mortality rates between 2–9%. However, many of these studies have not demonstrated a mortality benefit from thrombolytic therapy in a subset of patients with right ventricular myocardial infarction (RVMI) and/or right ventricular (RV) dysfunction accompanying inferior infarction. Importantly, the development of complications in this subgroup, associated with increased mortality, can significantly modify an otherwise favourable prognosis.1 Patients with inferior myocardial infarction who have concomitant RV involvement tend to have a poorer prognosis compared with those without RV involvement, and they are at greater risk of severe complications such as left ventricular failure, cardiogenic shock, serious ventricular arrhythmias, and death.2

Right ventricular infarction most commonly occurs as a complication of inferior wall myocardial infarction (IWMI), affecting approximately one third of such patients. In nearly half of these cases, RV infarction is hemodynamically significant. RV infarction is associated with anterior myocardial infarction in fewer than 10% of cases, while isolated RV infarction is rare.3,4 Clinically, patients with RV infarction may present with the classic triad of hypotension, clear lung fields, and elevated jugular venous pressure.1 RV infarction leads to reduced RV compliance, impaired RV filling, and a consequent decrease in RV stroke volume. In some cases, RV infarction may be masked by left ventricular systolic dysfunction manifesting as hypotension and pulmonary congestion.5

Quantitative evaluation of cardiac function has traditionally focused on the left ventricle (LV), with the right ventricle often described as the “forgotten ventricle,” despite the fact that it pumps a volume comparable to that of the LV in most individuals. Recently, the prognostic significance of RV function across various cardiac conditions has gained wider recognition,6 leading to increased emphasis on improving routine RV assessment.

Echocardiography remains the primary imaging modality for assessing RV structure and function and provides rapid, bedside hemodynamic information that can influence management decisions. Left ventricular ejection fraction (LVEF) is commonly used as a surrogate for global LV function; however, accurate evaluation of LV performance remains challenging. Strain imaging has demonstrated that a preserved ejection fraction does not necessarily equate to normal systolic function,7 and the relationship between ejection fraction (EF) and mortality is complex. Adverse outcomes are observed not only in patients with markedly reduced EF (<35–40%) but also in older, more comorbid individuals with preserved EF (>50%). This complexity is reflected in evolving international guidelines that propose prognostic LVEF thresholds, including the recent inclusion of “mildly reduced ejection fraction” in European guidelines,8 and “borderline/improved” categories in American guidelines. However, the evidence supporting these cut-offs is largely derived from trials on neurohormonal modulation or cardiac resynchronization therapy in chronic heart failure 9.

AIMS AND OBJECTIVES

1. To determine the incidence of right ventricular dysfunction in inferior wall myocardial infraction.

To assess complications associated with right ventricular dysfunction.

Study Design Source of data The study was conducted among 128 patients who are admitted with inferior wall myocardial infarction in the Department of General Medicine, Hassan Institute of Medical Sciences (HIMS), Hassan over a period of 12 months (March 2024 - February 2025). Study design Cross-sectional Study Study period 1-year Sampling period March 2024 - February 2025 Inclusion criteria Isolated inferior wall myocardial infarction [ST segment elevation >1mm in II, III and aVF, presence of Q waves in lead II, III and aVF, after confirming from cardiac biomarker] Patients age between 18-80 years Exclusion Criteria Patients with anterior, anteroseptal, lateral wall myocardial infarction COPD, pulmonary hypertension, cardiomyopathy, valvular heart disease with left to right shunt lesions pervious history of CABG.   Sample size estimation The data was collected from people who are admitted with inferior wall myocardial infarction in medical intensive care unit (MICU) in Department of General Medicine, HIMS, Hassan. The sample size was calculated based on incidences of right ventricular dysfunction of 43% in a study carried out by Vanajakshamma et al. The formula used for the sample size calculated was 128. Methodology The study was conducted among 128 patients who are admitted with inferior wall myocardial infarction in the Department of General Medicine, Hassan Institute of Medical Sciences (HIMS), Hassan over a period of 12 months after getting institution ethical clearance. A total 128 patients were recruited on admission to the intensive coronary care unit at Department of General Medicine, Hassan Institute of Medical Sciences, Hassan. Patients with confirmed diagnosis of inferior wall myocardial infarction and satisfying the inclusion and exclusion criteria were included in the study group. The diagnosis of inferior wall myocardial infarction was based on inclusion criteria. A detailed history with special reference to the cardiovascular system was taken. A through physical examination was done with emphasis on the cardiovascular system. 12-lead ECG was taken at admission for diagnosis. Patients with ST segment elevation myocardial infarction were subjected to blood Creatine Kinase-Myocardial Band (CK-MB) test and Troponin I estimations. 2-D echocardiographic analysis was done and right ventricular dysfunction was identified and incidence was calculated. The complications associated with right ventricular dysfunction was noted. Statistical Analysis SPSS (Statistical Package for Social Sciences) Version 23 (IBM Corp. IBM SPSS Statistics for Windows, Version 23.0. Armonk, NY: IBM Corp; 2015.]) was used to perform the statistical analysis. Data was entered in the excel spread sheet. Descriptive statistics of the explanatory and outcome variables were calculated by mean, standard deviation for quantitative variables, frequency and proportions for qualitative variables.Inferential statistics like Chi-square test was applied for qualitative variables to find the association.Independent sample t-test was applied to compare the quantitative parameters between the groups. p<0.05 was considered statistically significant.

Table 1: Position of the Mental Foramen (n = 140 sides)

Interpretation
The MF was most commonly located in line with the second premolar on both sides (52.9%), followed by between first and second premolars (16.4%). No foramina were found in line with the canine or molar regions.

Table 2: Morphometric Dimensions of the Mental Foramen

Interpretation:
No statistically significant difference was observed between sides (p > 0.05). The MF tends to be slightly larger horizontally on the right and vertically on the left.

In this study, the mean age of the participants was 57.3 years, with most patients belonging to the 51–60 and 61–70-year age groups. This distribution aligns with the well-recognized epidemiological trend of acute myocardial infarction occurring predominantly in middle-aged and older adults. Comparable findings have been reported in earlier studies, which observed a greater incidence of myocardial infarction after the 5th decade of life.10-11 The increasing burden of atherosclerosis, endothelial dysfunction, and age-related metabolic alterations likely contribute to this pattern. Furthermore, the relatively younger onset of myocardial infarction in developing countries has been attributed to early exposure to cardiovascular risk factors such as unhealthy diet, physical inactivity, psychosocial stress, and limited preventive healthcare access.12

A clear male predominance was noted in our study, with males constituting 75% of the study population. This observation is consistent with prior reports showing a higher prevalence of myocardial infarction among men than women.13 Biological factors, particularly the cardioprotective effects of estrogen in premenopausal women, are thought to delay the onset of coronary artery disease in females. Additionally, lifestyle and behavioral factors such as higher rates of smoking, alcohol intake, occupational stress, and reduced healthcare-seeking behavior among men may further explain this disparity. However, this gender difference diminishes with advancing age, especially after menopause, when hormonal protection declines.

The incidence of RVD in the present study was 28.1% based on echocardiographic assessment. This rate is comparable to those reported in previous studies, which documented RVD in approximately 25–33% of patients with IWMI.14 Variations across studies may be attributed to differences in study design, patient selection, timing of echocardiography, and diagnostic criteria. Early echocardiographic evaluation may identify transient dysfunction, whereas delayed assessment may underestimate the true prevalence.15.

Most patients in this study exhibited mild to moderate RVD, with severe dysfunction observed in only 1.6% of cases. Similar trends have been reported previously, where severe RVD was less common but associated with poorer outcomes and higher mortality.16 The predominance of mild to moderate dysfunction highlights the importance of sensitive diagnostic techniques. Echocardiography remains central to evaluating right ventricular size, systolic function, and hemodynamic impact. Early detection of even mild RVD is clinically important, as it may progress or predispose patients to complications if not adequately managed.

Right ventricular dysfunction is a common and clinically significant finding in inferior wall myocardial infarction. Echocardiography, combined with right-sided ECG leads, play a vital role in early detection, prognostication, and prediction of complications. Routine assessment of right ventricular function should be an integral part of the evaluation of patients with inferior wall myocardial infarction.

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