FREQUENCY OF CORONARY ARTERY DISEASE USING CALCIUM SCORING BY 640 SLICE CT

Coronary artery disease is the narrowing of coronary arteries which is usually caused by the atherosclerosis that leads to restriction of blood flow to the heart muscles. Atherosclerosis is a buildup of plaque or deposition of fats on the inner walls of arteries and is calculated by calcium scoring. Calcium scoring is a test to assess the presence and degree of plaque in the coronary arteries. Objective: To find the frequency of coronary artery disease using calcium scoring by 640 slice CT.   Methods: A descriptive study was conducted at Punjab Institute of Cardiology, Lahore. 155 participants including 117 (75.5%) males and 38 (24.5%) females were selected through convenient sampling technique. SPSS version 21.0 was used for data analysis. Results: Analysis of data showed that out of 155 patients, 54 (34%) patients had no lesion and 101 (65.2%) had CAD. Only 2 patients had 5 lesions. Out of 117 males, 38 had no plaque and 40 males had moderate plaque in coronary arteries. Out of 38 females, 16 female patients had no plaque, 5 female patients had moderate plaque. 99 (63.9%)  patients were non-smokers, out of them, 46 patients had no plaque and 17 patients had moderate plaque. 56 (36.1%) patients were smokers, out of these 8 had no plaque and 28 patients had moderate plaque. In total 103 (66.5%) patients who were hypertensive, 28 patients had no plaque, 36 had moderate plaque. Out of 52 (33.5%) patients who were without hypertension, 26 patients had no plaque, 36 patients had moderate plaque. Out of 155, 94 (60.6%) patients had diabetes, out of these 27 patients had no plaque, 32 patients had moderate plaque. Of 61 (39.4%) patients with diabetes, 27 had no plaque, 13 were with moderate plaque. 52 patients who were between the age of 26-35 years, 18 patients had no plaque, 14 patients had moderate plaque and of 8 patients between the age of 66-75 years, 3 had moderate plaque. Conclusions: In our sample the ratio of males was greater than females. In males, moderate plaques are most common and most of the females are those with no plaque. 54 % patients have no plaque and only 3 patients have minimal plaque. Smokers were least affected. It is concluded that hypertension affects the population more than any other risk factor. From our study it is also concluded that the people within the age range of 26 to 35 years are most likely to develop CAD Key words: Computed Tomography, Calcium Scoring, Coronary Artery Disease DOI: 10.7176/JHMN/71-13 Publication date: February 29 th 2020

minimum of 3 contiguous pixels were utilized for identification of a calcific lesion. Each focus exceeding the lowest criteria was scored using the algorithm experienced by Agatston et al. calculated by multiplying the lesion area by a density factor acquired from the maximal HU within this area. The density factor was allocated in the following manner: 1 for lesions with highest attenuation of 130 to 199 HU, 2 for lesions with highest attenuation of 200 to 299 HU, 3 for lesions with highest attenuation of 300 to 399 HU, and 4 for lesions with highest attenuation 400 HU. The total CAC score was determined by summing individual lesion scores from each of anatomical sites (left main, left anterior descending, left circumflex, and right coronary arterie). 7 The mean Hounsfield units for the largest calcification (density 150 mg/cm3) in a large region of interest was measured for 120-kVp acquisition. 8 From the primary analysis, these CCTA scores were calculated: Coronary obstruction score was obtained by counting the most significant plaque or stenosis of any segment; score 0, all coronary segments<25% and without any plaques; score 1, at least 1 coronary segment with non-obstructive plaques (25% stenosis); score 2, at least 1 coronary segment with mild stenosis (25% to 49%); score 3, at least 1 coronary segment with moderate stenosis (50% to 74%); and score 4, at least 1 coronary segment with severe stenosis ( 75%). 9 If subjects were current smokers, they were considered to have a positive history of cigarette smoking. 10 Other risk factors were recorded as categorical variables in all patients. Diabetes was defined as treatment with hypoglycemic agents or insulin, fasting glucose >126 mg/dl. Hypertension was defined as blood pressure >140/90 mm Hg. 11 The purpose of this study was to get prevalence of coronary artery disease using calcium scoring in the evaluation of coronary artery lesions in cardiac and non-cardiac patients for future coronary artery disease risk.

Methods:
It was a descriptive study conducted from July 2019 to October 2019. The study was performed at Punjab Institute of Cardiology, Lahore. Data was collected by using a pre-tested questionnaire with the help of convenient sampling technique. 155 participants aged between 19 and 75 years, were selected. After data collection, data were arranged in Microsoft Excel Sheet and were analysed by using Statistical Package for the Social Sciences (SPSS) software version 21.0.

Results:
A total of 155 patients were included in this research comprising 117 males (75.5%) and 38 females (24.5%). 101(65.2%) patients had CAD and 54(34.8%) had no CAD. 38 male patients had no plaque in coronary arteries, 1 male patient had minimal plaque, 27 male patients had mild plaque, 40 male patients had moderate plaque and 11 male patients had severity of plaque in their coronary arteries. 16 female patients had no plaque, 2 female patients had minimal plaque, 15 female patients had mild plaque, 5 female patients had moderate plaque in coronary arteries as shown in Table 2.    99(63.9%) patients were non-smokers and 56(36.1%) patients were smokers, 46 non-smokers had no calcification, 3 non-smokers had minimal calcification, 30 non-smokers had mild calcification, 17 non-smokers had moderate calcification and 3 non-smokers had severity of calcification in this study. 8 smokers had no calcification, 12 smokers had mild calcification, 28 smokers had moderate calcification and 8 smokers had severity of calcification in this study as shown in Table 3.  Table 4.   Table 5.  In this study, there were 54 patients who had no lesion, 37 patients who had 1 lesion, 35 patients who had 2 lesions, 18 patients who had 3 lesions, 9 patients who had 4 lesions and only 2 patients who had 5 lesions in coronary arteries as shown in Table 6 Journal of Health, Medicine and Nursing www.iiste.org ISSN 2422-8419 An International Peer-reviewed Journal Vol.71, 2020 108  Table 7 Journal    The frequency of patients with diabetes is 16(10.3%), frequency of diabetes and smoking is 5(3.2%), frequency of hypertension is 34(21.9), frequency of hypertension smoking and diabetes is 9(5.8%), frequency of hypertension and diabetes is 31(20%), frequency of hypertension and smoking is 30(19.4%), frequency of normal patients is 18(11.6%) and frequency of smokers is 12(7.7%) as shown in Table 11.  The current study was designed to find out the frequency of CAD using calcium scoring. The severity of atherosclerotic process in arteries is predicted by presence of calcification in coronary arteries. The coronary artery calcium score predict the future coronary artery disease. The frequency of coronary artery disease is 65.2%. According to the results of current study, out of 155 patients, 66.5% had hypertension, 39.4% patients were diabetic and 11.6% patients had no risk factor. Nobuo Tomizawa et al. 12 conducted a study in 2015 to determine the difference of coronary artery disease (CAD) severity and a characteristics of plaque between patients with either one of hypertension, diabetes or dyslipidemia. Their sample size was large compared to ours. Out of the 1,161 patients, 38% patients had hypertension, 7% patients were diabetic, 21% patients had dyslipidemia. In our study 34.8% patients are without any lesion and according to their study 34% patients had no disease. In our study, 11.6% patients had no risk factor associated. All of their patients had one or more risk factor. According to our study the affected males (75.5%) were more than affected females (24.5%). In our study, hypertension is the commonest risk factor contributing to coronary artery disease. Findings of their study supports our results that patients with HTN and diabetes were also more often males and the frequency of people with hypertension was greater than diabetic people. Another similarity in both studies is that the frequency of "no plaque" is greater in non-diabetic people. From both studies, it is concluded that male's patients are more affected than females and frequency of HTN is greater than any other risk factor.
They also concluded that hypertensive people had higher frequency of no plaque which is opposite to our study, according to our results, most of the hypertensive patients suffer from moderate plaque.
Another study was conducted by Nathan D. Wong et al, 13 they compared the extent and prevalence of metabolic syndrome (MetS) , diabetes or neither condition. They also had a large sample size as compared to us (1,823). They reported that 67% of patients with diabetes had coronary calcification. In our study, 39.4% patients were diabetic. In 2015, John W. McEvoy et al, 14 conducted a study. The outcome of this study suggested that 14% were smokers, former smokers were 39% and those who never smoked were 47% and in our study 63.9% participants were non-smokers which implies that in our population, smoking is not a very big contributing factor toward coronary artery disease. The results of their study showed, smokers had CAC > 100, this supports our result as, frequency of moderate plaque (CAC > 100) is greater in smokers in our study. From our study it is also concluded that frequency of moderate plaque is greater.

Conclusion
Estimation of coronary artery disease has been done by measuring calcification in coronary arteries by multislice CT. In our study the ratio of affected males was greater than affected females because our sample population had more males. Moderate plaques were more common in males. However, the commonest females are those with no plaque. CAD is less frequent in smokers as compared to patients with other risk factors. The ratio of diabetic patients was more than smokers but less than hypertensive people. Most of our patients with CAD were hypertensive. It is concluded that hypertension affects more than any other risk factor in our population. 34.8% of the scanned patients had no plaque and the most common plaque was moderate (29.0%) in type. Age range of 26 to 35 years is most prone to develop CAD. Severe plaque in coronary arteries are found in age range of 26 to 35 years. Most of the patients (both genders) have single lesion involvement in CAD. Patients having 5 lesions were least common.