This was a single-center, prospective observational study, and the data were collected for a period of 12 months, between November 2022 and November 2023. Patients aged ≥18 years and presenting with ACS were studied. Patients with valvular heart disease, cardiomyopathy, previous left bundle branch block, myocarditis (diagnosed clinically by history of viral prodrome, history of fever preceding for days to weeks, atypical or non-anginal chest pain, and global hypokinesia on echocardiography), chronic stable angina, acute or chronic liver disease, renal impairment (eGFR <60 mL/kg/1.732m²), and secondary conditions that could precipitate angina (anemia, arrhythmias, and fever) were excluded. Out of 800 patients who were diagnosed with ACS and admitted to the department in the previous year, a sample of 400 patients was considered after excluding those who did not give consent and other factors

All the consecutive patients included in the study were thoroughly evaluated. The patient history was documented in detail, and focused clinical examination was performed. Acute myocardial infarction was diagnosed according to the Fourth Universal Definition of Myocardial Infarction [11] . Non-ST segment elevation myocardial infarction (NSTEMI) or unstable angina (USA) was defined as per the 2014 American Heart Association (AHA)/American College of Cardiology (ACC) non-ST elevation-acute coronary syndrome (NSTE-ACS) guidelines [12] . The occupation of the patients was used to determine the physical activity status (metabolic equivalent) as light activity with less than 3 metabolic equivalents (METS), moderate activity with 3 - 6 METS, and vigorous activity with more than 6 METS [13] .

CAD risk factor profiles collected and definitions:

Two-dimensional echocardiography was performed on all of the study subjects before thrombolysis or percutaneous coronary intervention (PCI) using the Philips Affiniti 50 machine. Invasive coronary angiography (CAG) via radial arterial access was performed in most of the patients either as a part of primary/rescue PCI or before discharge (within 48 - 72 hours of the index event) if the patient has already been thrombolyzed or managed conservatively. Data regarding thrombolysis in myocardial infarction (TIMI) flow characteristics, the presence of calcium, and the presence of a thrombus was recorded. Expert opinion on coronary angiography was taken by two cardiologists.

Stenoses was defined as minimal if the narrowing was visually less than 50%; moderate, if it is between 50% and 70%, and severe, if it is 70% or more [22] . Significant left main stenosis was defined as luminal diameter reduction of >50% [23] . Obstructive CAD was considered to be present if ≥70% diameter stenosis was present on visual assessment in one of the major epicardial coronary arteries. Multi-vessel disease was defined as ≥50% stenosis of ≥2 major epicardial coronary arteries.

The Gensini score was used to quantify the severity of CAD, where a zero score suggests the absence of CAD. The Gensini score accounts for the degree of coronary artery narrowing as well as the location of the narrowing. Points will be given for narrowing as follows: 1 point: 25% stenosis, 2 points: 26% - 50% stenosis, 4 points: 51% - 75% stenosis, 8 points: 76% - 90% stenosis, 16 points: 91% - 99% stenosis, and 32 points: total occlusion (100%). After that, each lesion was multiplied by a factor that accounts for the importance of the lesion’s position in coronary circulation: 5 for the left main coronary artery; 2.5 for proximal LAD and LCX; 1.5 for mid LAD; 1.0 for the RCA, distal segment of LAD, posterolateral artery, and obtuse marginal; and 0.5 for other segments. In left dominant circulation, a factor of 3.5 for proximal LCX and 2 for distal LCX. The Gensini score was derived by adding the individual coronary segment scores. Patients was divided into three groups based on their Gensini score: the first tertile (Gensini score <11 points), the second tertile (Gensini score 11 - 38 points), and the third tertile (Gensini score >38 points) [24] [25] .

Patients were treated according to the latest MI management guidelines [26] . Routine blood investigations was performed at the time of admission. Informed consent was obtained from all subjects as per the existing norms of the institutional ethics committee.

The results are reported as the mean ± standard deviation for the quantitative variables and percentages for the categorical variables. The groups are compared using the student’s t-test for the continuous variables and the Chi-square test for the dichotomous variables, and p<0.05 are considered statistically significant. All the statistical analyses are carried out via Statistical Package for Social Sciences version 20 (SPSS, IL, Chicago Inc., USA).

Sample size of the study was 400 patients. The mean age of the study population was 55 ± 11.78 years. The most common age groups presenting with ACS were 51 - 60 years, 41 - 50 years, and 61 - 70 years, with 114 (28.5%), 105 (26.3%), and 103 (25.8%) cases, respectively. Male and female ratio was 2.4:1. Out of 400 patients, 111 (27.8%) were found to have premature coronary disease. The majority of the patients (80%) were from a rural background and 24% of patients were illiterate. The demographic profile of patients is shown in Table 1 .

Smoking was the most common risk factor seen in the study population, which was present in 206 (51.5%) patients, and 162 (40.5%) patients had hypertension, as shown in Figure 1 . Out of 400 patients, 133 (33.2%) had a history of ischemic heart disease (IHD), and only 6 (1.5%) had a previous episode of stroke. Diabetes was present in 114 (28.5%) patients. A family history of premature CAD and obesity was present in 65 (16.3%) patients and 25 (6.3%) patients, respectively.

The most common symptom at the time of presentation was chest pain, found in 86.5% of patients, followed by dyspnea in 5.8%. Chest heaviness, left arm pain, palpitation, uneasiness (ghabrahat), throat pain, and sweating are less commonly reported complaints, each accounting for 3.5%, 1.0%, 1.0%, 0.8%, 0.5%, and 0.5% of the cases, respectively, as shown in Table 2 . Cardiac markers were positive in 25% of the patients and negative in 75% of patients. Clinical profiles of the patients are shown in Table 2 .

CAD: Coronary artery disease; IHD: Ischemic heart disease; SD: Standard deviation; TIA: Transient ischemic attack.

AWMI: Anterior wall myocardial infarction; IWMI: Inferior wall myocardial infarction; LWMI: Lateral wall myocardial infarction; NSTEMI: Non-ST-elevation myocardial infarction; USA: Unstable angina.

In majority of the cases, the patients were performing light physical activity before developing ACS (61.8%), followed by vigorous physical activity (20.3%) and no physical activity (16.8%). Out of 76 patients with STEMI, 55 patients belong to Killip I and 17 patients belong to Killip II. Only 1 patient was in Killip III and 3 patients were in Killip IV.

There was considerable variability in the time taken by patients to seek medical attention after experiencing symptoms. As shown in Figure 2 , within the first 24 hours, 66.8% of the patients sought medical assistance and only 38.5% of the patients received definitive treatment, suggesting of significant delay in treatment. Unstable angina is the most common type of ACS (68%), followed by STEMI (19%) and NSTEMI (12.75%). Out of 19% of STEMI patients, IWMI (9%) is the most common, followed by AWMI (8.5%) and LWMI (1.5%).

Coronary angiography revealed that 39% of patients had single vessel disease (SVD), 23.5% had double vessel disease (DVD), and 27.5% had triple vessel disease (TVD) as shown in Table 3 .

CAD: Coronary artery disease; DVD: Double vessel disease; LAD: Left anterior descending; LCX: Left circumflex; RCA: Right coronary artery; SVD: Single vessel disease; TVD: Triple vessel disease.

Obstructive CAD was the most prevalent, affecting 63% of the patients, and recanalized/non-obstruction was observed in 16.25% of patients. Total occlusion was found in 15.75% of patients and normal coronary arteries were found in 10% of participants. Figure 3 depicts the angiographic profile of patients.

LAD was the most commonly affected vessel in the study population (317 [79.2%]). The right coronary artery (RCA) was affected in 223 patients (55.7%), LCX was affected in 150 patients (37.5%), and the left main coronary artery was affected in 55 patients (14%).

Descriptive data regarding the angiographic pattern seen in various coronary arteries shown in Figure 4 .

Mean Gensini score is 33.24 ± 34.67 (0.00 - 152.00). Patients were divided into three groups based on their Gensini score: the first tertile (Gensini score <11 points), the second tertile (Gensini score 11 - 38 points), and the third tertile (Gensini score >38 points). Figure 5 shows that 33.2% of patients belong to Group I, 34.2% belong to Group II, and 32.5% belong to Group III.

Discussion: This prospective study, which was carried out in the state of Haryana, is the first of its kind to investigate the demographic, clinical, and coronary angiographic profiles of patients diagnosed with ACS. The mean age of the study population was 55 ± 11.78 years. The most common age groups presenting with ACS were 51 - 60 years, 41 - 50 years, and 61 - 70 years, with 114 (28.5%), 105 (26.3%), and 103 (25.8%) cases, respectively. Similar observations were reported by the CREATE registry (2008) [3] , the Kerala ACS registry (2009) [4] , Sharma et al. (2017) [27] , Bansal et al. (2016) [28] , Nayak et al. (2022) [29] , and Adil et al. (2023) [30] . In the study conducted by Ahsan et al., the mean age of the participants was 47.74 ± 12.23 years [31] .

In the present study, out of 400 cases of ACS studied, 283 (70.75%) were males and 117 (29.25%) were females, with a male and female ratio of 2.4:1. Similar to our study, various other authors, such as the CREATE registry (2008) [3] , the Kerala ACS registry (2009) [4] , Deshmukh et al. (2019) [32] , and Mohamed et al. (2019) [33] , had shown male predominance. The number of female participants was smaller, which is in line with the records from earlier studies. One potential reason for this is the variation not just in gender inequalities across different global locations, but also in a variety of aspects, including accessibility to healthcare, local practices, and the availability of resources. Culture, economy, and the provision of healthcare are the areas in which there are major differences across the world.

Premature CAD (males <45 years; females <55 years) was found in 111 patients (27.8%), whereas Khan HU et al. (2014) [34] found 12% of patients aged <40 years having CAD.

The majority of the study population in the present study belonged to rural areas (80%) and was illiterate (24%) similar to the study conducted by Sharma YP et al. (2021) [35] . However, the study conducted by Gupta et al. (2020) [36] included the majority of the study population from urban and semi-urban regions. In the present study, 43% of patients had occupations with light physical activity based on metabolic equivalents, which is consistent with the data from the study conducted by Nayak et al. [29] .

In the present study, the largest proportion of participants relates to Grade III of the Modified B. G. Prasad socioeconomic scale, comprising 31.0% of the cohort. Similar to our observation, Gupta et al. (2020) [36] had a majority of patients belonging to the middle-class group, whereas the majority of the patients in studies from Sidhu et al. (2020) [37] and Ahsan et al. (2023) [31] belonged to lower socioeconomic backgrounds.

Risk factors such as a family history of CAD, dyslipidemia, hypertension, diabetes mellitus (DM), smoking, and obesity play a role in the development of CAD. In the current study, 16% of patients had a positive family history of CAD, whereas a study by Mirza et al. (2018) found that 24% of patients had such a history [38] . There is a similarity in the results, and an easy comparison can be made between them. Results of the current study showed that 28% of the patients had diabetes, 40% had hypertension, 51% were smokers, and 6% were obese. The present study showed that a family history of CAD at an early stage and smoking are two of the most significant risk factors for ACS. As per a study conducted by Ahsan et al. (2023) [31] , patients diagnosed with CAD tended to have high rates of both diabetes and hypertension as risk factors. Similar to our observation, smoking was found to be an important risk factor in the studies conducted by Mohamed et al. (2019) [33] , Deshmukh et al. (2019) [32] , and Gupta et al. (2020) [36] . There is a correlation between smoking and increased risk of developing CAD.

One of the most important factors that determine the treatment, outcomes, and prognosis of patients experiencing ACS is the timing of their initial contact with medical professionals [39] . When it comes to cases of ACS, fast access to medical care is absolutely necessary [40] . This is especially true in the case of STEMI, where prompt reperfusion therapy has the potential to significantly improve survival rates and reduce mortality. Within the first 24 hours, around 67% of the patients sought medical assistance, but only 38.5% of the patients got definitive treatment, which was statistically significant in relation to the diagnosis of ACS, as demonstrated by the findings of the current study. This can be attributed to illiteracy, misinterpretation of symptoms, lack of rapid transport modalities like ambulances, lack of hospitals equipped with percutaneous coronary intervention/coronary artery bypass grafting, and inadequacy of financial resources. Similarly, in the study conducted by Revaiah et al. [41] , the median time to first medical contact and revascularization was 5 hours and 48 hours, respectively, whereas in the CREATE registry (2008) [3] , the median time from symptoms to hospital was 6 hours, with 50 (25 - 68) minutes from hospital to thrombolysis. Sharma YP et al. (2021) [35] conducted a study and found that the median time to hospital admission was 10 hours for STEMI patients.

The most common symptom at the time of presentation was chest pain, found in 86.5% of patients, followed by dyspnea, found in 5.8% of patients, which is similar to a study by Bansal et al. [28] As per the Kerala ACS registry (2009) [4] , Sharma et al. (2014) [6] , Gupta et al. (2020) [36] , and Revaiah et al. [41] , STEMI was the most common kind of ACS. However, as per the present study, the most prevalent form of ACS was found to be USA, which accounted for 68% of all cases, followed by STEMI (19%) and NSTEMI (12.75%). Similarly, USA was found to be the most prevalent presentation in the study conducted by Ahsan et al. (2023) [31] .

Out of 19% of STEMI patients, IWMI (9%) was the most common, followed by AWMI (8.5%) and LWMI (1.5%). In contrast to the results of the present study, AWMI was the most common STEMI in studies conducted by Deshmukh et al. (2019) [32] and Gupta et al. (2020) [36] . Revaiah et al. [41] observed that the most common diagnosis was AWMI (58%), followed by IWMI (23%) and NSTE-ACS (18%). Killip I was the most common class as per the present study, showing concordance with earlier studies, namely Sharma et al. (2017) [27] .

Coronary angiography revealed that 10% of patients had normal coronary arteries. Non-obstructive CAD was present in 16.25% of patients, while 63% were diagnosed with obstructive CAD, which is comparable to other studies like Deshmukh et al. (2019) [32] and Raju et al. (2023) [42] where obstructive CAD was found in 61% and 70.3%, respectively. Normal coronary arteries were reported in 22.25% and 35% of patients in a study by Adil et al. (2023) [30] and Ahsan et al. (2023) [31] , respectively.

Coronary angiography revealed that 39% of patients had SVD, 23.5% had DVD, and 27.5% had TVD. SVD was found to be dominant in other studies as well, such as studies by Sidhu et al. (2020) [37] and Sharma YP et al. (2021) [35] . DVD was found to be most common in the study by Adil et al. (2023) [30] .

Our study revealed LAD as the most commonly involved vessel in 317 patients (79.2%), followed by RCA in 223 patients (55.7%), LCX in 150 patients (37.5%), and the left main (LM) in 55 patients (14%). Results similar to the current study were seen in various studies, namely Bansal et al. (2016) [28] , Sharma et al. (2017) [27] , and Khan et al. (2020) [34] .