European Journal of Cardiovascular Medicine

Coronary artery disease is a major public health concern as it is reported to be the leading cause of mortality (1,2). Acute myocardial infarction in young adults is not common. The Framingham Heart Study’s 10-year follow-up data revealed that the incidence of MI was 12.9, 38.2, and 71.2 per 1000 in men and 2.2, 5.2, and 13.0 per 1000 in women within the age groups of 30 to 34, 35 to 44, and 45 to 54 years, respectively (3). However, Mammi et al concluded that in India, about 10-16% of acute myocardial infarction occurs in young individuals (4). In younger population, smoking and family history of ischemic heart disease are more frequently observed as risk factors (5). Although short term prognosis for these patients is better, long-term outcome has been reported to be poor as 15 years after the index myocardial infarction, mortality rates are high (6). Hence, myocardial infarction in young individuals is an important entity. Identifying the risk factors is necessary for risk factor modification and primary and secondary prevention (7,8).

The present study was a hospital based cross sectional observational study and was conducted on 86 patients aged between 18 and 45 years in Department of Medicine and Department of Cardiology, IGMC Shimla from 1^st May 2019 to 30^th April 2020.

Inclusion Criteria

• Non pregnant individuals of age between 18 and 45 years diagnosed with acute myocardial infarction admitted in medicine and cardiology ward.

Exclusion Criteria

• Patients not willing to participate in the study.
• Patients of age < 18 years or > 45 years.
• Pregnant females.

Informed consent was taken from all the patients. The data including demographic profile of patients and detailed history was collected. History focusing on possible risk factors was taken including history of tobacco smoking, diabetes mellitus, hypertension, positive family history of premature CAD, dyslipidemia and drug abuse. BMI of the patients was calculated.

Ten milliliters of venous blood was collected aseptically by venipuncture and transferred aseptically from syringe into sterile vacutainers. High sensitivity Troponin I was done by chemiluminescent micro particle immunoassay. Lipid profile and blood sugar were measured using photometric analysis and glycosylated hemoglobin was measured using high performance liquid chromatography ion exchange method. Nephelometric analysis was used to measure Apolipoprotein A and Apolipoprotein B. Homocysteine levels were measured through chemiluminescence. Twelve lead ECG was done using Heidelco medicore private limited model HE310. Coronary angiography was planned in all the patients, but due to financial and technical issues, it was done in 59 patients. Complications that developed during the hospital stay of the patients were also documented.

Based on ECG, STEMI was diagnosed when ST segment elevations reach threshold values in two or more anatomically contiguous leads. In men >40 years of age, threshold value for abnormal ST-segment elevation at the J point is ≥2 mm in leads V2 and V3 and >1 mm in all other leads. In men <40 years of age, threshold value for abnormal ST-segment elevation at the J point in leads V2 and V3 is >2.5 mm. In women, the threshold value of abnormal ST-segment elevation at the J point is >1.5 mm in leads V2 and V3 and >1 mm in all other leads. In right-sided leads (V3R and V4R), the threshold for abnormal ST elevation at the J point is 0.5 mm, except in males,30 years in whom it is 1 mm. In posterior leads (V7, V8, and V9), the threshold for abnormal ST elevation at the J point is 0.5 mm. NSTEMI was diagnosed as raised high sensitivity troponin I in patients with new onset ST segment depression or deep T wave inversions (≥0.3 mV) or having chest discomfort suggestive of ACS without significant ST-T changes. Threshold value for abnormal J-point depression was taken as 0.5 mm in leads V2 and V3 and 1 mm in all other leads.

Lipid abnormalities were detected using deviation from normal reference values as total cholesterol less than 200 mg/dL, LDL cholesterol less than 130 mg/dL, HDL cholesterol more than 40 mg/dL in males and more than 50 mg/dL in females and triglycerides less than 150 mg/dL. Diabetes mellitus was defined as glycosylated hemoglobin more than or equal to 6.5%, fasting blood glucose more than or equal to 126 mg/dL and random blood glucose more than or equal to 200mg/dL. Normal apolipoprotein A1 and apolipoprotein B levels were taken as 0.89-1.86 g/L and 0.53-1.73 g/L respectively while normal homocysteine levels were 5.46-16.20 µmol/L. Data collected was entered in excel sheet and accuracy of data entered was checked. Categorical variables were expressed as frequencies and percentages.

A total of 808 patients were admitted with acute MI during the one-year study period, out of which 86 (10.64%) were of age less than 45 years and were included in the study. 722 (89.36%) patients were of age more than or equal to 45 years. In the study group, the mean age was 38.4 years. 53.48% patients were in age group of 40-45 years while maximum patients (77.9%) belonged to the age group of 35-45 years. Minimum and maximum ages were 21 years and 44 years, respectively. 86.7% patients belonged to rural areas and 13.3 % patients were from urban areas. Male predominance was observed with 89.5% of total patients being male and 10.43% patients were female.

Table 1: Distribution of acute myocardial infarction among different age groups and sex

In the present study, smoking was the most common risk factor present in 93.02%. 5.81% patients smoked more than 20 pack years. Majority of the smokers were in the age group of 40-44 years. Hyperhomocysteinemia was present in 84.88% patients while 82.55% patients had ratio of ApoB/ApoA1>0.8. Most common lipid abnormality observed was raised LDL followed by low HDL. High LDL was seen in 67.44% with mean LDL of 112.5 mg/dl. Low HDL was seen in 65.11% patients. Total cholesterol was raised in 53.48% patients while high triglycerides were seen in 51.16% patients. Diabetes Mellitus was prevalent in 36.04% patients in this study. Mean HbA1c levels in these patients was 7.9%. 22% of these were diagnosed with Diabetes Mellitus after admission. 26.75% patients were hypertensive in this study. Mean systolic blood pressure was 116 mm of Hg and mean diastolic blood pressure was 72 mm of Hg. 54% of these patients were compliant to treatment. Family history of premature CAD was present in 17.44% cases, while 1.16% had history of premature CAD in both the parents. 62.79% patients were overweight in this study while 17.44% were obese and only 19.76% patients had normal BMI. 16.27% patients had history of drug abuse.

Table 2: Risk factors

STEMI was the more prevalent type of myocardial infarction with 72.09% patients showing ST segment elevation on ECG. 27.90% cases exhibited features of NSTEMI on ECG. Anterior wall and anterolateral wall were the most common areas involved with prevalence of 35.4% and 30.6% respectively. Isolated inferior wall was involved in 14.5% cases, whereas 12.9% cases had concomitant involvement of inferior wall and right ventricle.

Table 3: Type of myocardial infarction

Coronary angiography was done in 59 patients. Most common abnormality seen on coronary angiography was single vessel disease, seen in 62.71% patients followed by double vessel disease seen in 22.03% patients. Triple vessel disease was seen in 5.08% cases while 10.16% cases had normal coronaries. Left anterior descending artery was the most common vessel involved.

Table 4: Coronary angiography findings

Cardiogenic shock was seen in 3 patients (3.4%) while arrhythmia was documented in 1 patient. Mortality was seen in all 3 patients who developed cardiogenic shock.

The study of ischemic heart disease in young individuals is important in the era of preventive cardiology. A total of 808 patients were admitted with acute MI during the one-year study period, out of which 86 (10.64%) were of age less than 45 years and were included in the study.

The age distribution in our study was fairly consistent with findings of other related studies. Maximum patients (53.48%) were in age group of 40-45 years similar to study done by Mulay et al and Vaidhya et al(9,10). Mean age was 38.4 years in concordance with previous studies (11,12). Majority (89.5%) of our patients were male, which is consistent with various previous studies (9,11,12,13). The majority (86.7%) of patients in our study belonged to rural areas which is consistent with the demography of Himachal Pradesh where about 90% of population lives in rural areas.

ST-elevation myocardial infarction (72%) was more common than non-ST- elevation myocardial infarction (28%) in the current study similar to study done by Ravi et al (69.2%) but less when compared with the studies conducted by Shah et al (98.13%) and Tamarkar et al  (14,11,16). Anterior wall and Anterolateral wall were the most common areas affected by myocardial infarction with prevalence of 35.4% and 30.6% respectively that correlate well with previous studies(11,12,14). Inferior wall involvement was seen in 33.86% patients as seen by Ravi et al(14).

In the present study, tobacco smoking was the most prevalent risk factor present in 93.02% of the subjects. This is in alignment with the study conducted by Zimmerman et al(17). Numerous other studies have highlighted the increased rates of tobacco use among young patients who present with myocardial infarction, including Sinha et al (78.5%), Tamarkar et al(64.3%) and Bhardwaj et al (18,15,12) Hence, health education programs should focus on smoking abstinence in order to prevent the incidence of AMI in young individuals. Approximately 1 of every 4 nonfatal MIs in persons aged 18 to 45 years was attributable to frequent cocaine use in a survey done by Qureshi et al(23). Our study recorded drug abuse in 16.27% patients similar to DeFillipis et al who found that use of cocaine and/or marijuana was present in 10.7% patient population (23). However, according to Tamarkar et al, history of recreational drug abuse was found in 4.3% of their patients only(14).

More than half of the patients had dyslipidemia with raised LDL present in 67.4% patients followed by low HDL in 65.11% patients. These findings are similar to the study performed by Akram et al who found that about 76% of patients suffered from dyslipidemia with most common lipid abnormality being raised LDL followed by low HDL(16). However, Vaidhya et al and Tamarkar et al found dyslipidemia in only 15.3% and 9.6% patients(10,15). These differences in lipid parameters may due effect of dietary, genetic and environmental factors on lipid metabolism.

Majority of the patients were overweight (62.79%) or obese (17.44%). This is lower in comparison to previous study done by Akram et al where 56% of study subjects were obese (16). This discrepancy was probably due to the fact that Himachal Pradesh is a hilly state where the majority of the population depends directly on agriculture, horticulture and pastoralism for earning their livelihood.

Hypertension and Diabetes mellitus was recorded in 26.74% and 36.04% patients respectively, similar to previous studies (15,14). Various studies have demonstrated a recent increase in the prevalence of hypertension from 8.86% to 27.7% and hyperglycemia from 7.6% to 36.15%  in young CAD(22). There is abundant evidence that the risk of CAD is related to plasma lipid and apolipoprotein levels(19). Abnormal Apo B/ Apo A1 ratio was seen in 82.55% patients in the present study in concordance with previous study done by Modi et al(20). Hyperhomocysteinemia was present in 84.88% patients in our study, as reported by Kumar et al(21).

On angiography, 10.16 % had normal coronaries in line with study done by Bhardwaj et al In those who had obstructive disease, single vessel disease was evidently more common, which has also been reported by other studies double vessel disease and triple vessel disease were seen in 22.03% and 5.08% cases, respectively(12,15,18). Left anterior descending was the commonest vessel involved.

In hospital mortality was seen in 3.4% patients and all of them had cardiogenic shock. Similarly, Shah et al reported 4.7% mortality in their study which was primarily contributed by cardiogenic shock which was the commonest post-MI complication (11). Also, Fournier et al observed that in hospital mortality was 3.7% in their study (25).

In conclusion, acute myocardial infarction in young patients is more common in men in the Sub-Himalayan region. Smoking was the most common risk factor for myocardial infarction which was seen in young adults. The cessation of smoking would play a major role in preventing myocardial infarction in young adults. In our study, majority of the patients had raised Apo B/ Apo A1 ratio and increased homocysteine levels. This reinforces the notion that measurement of apolipoproteins and homocysteine levels can be used to predict the risk of cardiovascular disease in this population group. Most common lipid abnormality observed was raised LDL followed by low HDL. Most of the patients presented with ST elevation myocardial infarction with involvement of anterior wall. Majority of the patients had single vessel disease which was seen on coronary angiography. In hospital mortality was low.

Early diagnosis and early interventions are essential for young myocardial infarction patients to reduce mortality. Education of patients about smoking cessation, control of diabetes, hypertension and also education about modification of other risk factors of young MI can serve as primary prevention for the disease, since myocardial infarction in young individuals has remarkably more deleterious effects because of long life expectancy and more active lifestyle in this population group as compared to elderly population.

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