Extent of coronary atherosclerosis in diabetic and nondiabetic patients by multislice CT calcium scoring

Ahmed A Reda; Ahmed M Al Kersh; Mohamed M Al Sherif

doi:10.4103/1110-2098.192450

ORIGINAL ARTICLE

Year : 2016 | Volume : 29 | Issue : 2 | Page : 437-442

Extent of coronary atherosclerosis in diabetic and nondiabetic patients by multislice CT calcium scoring

Ahmed A Reda¹, Ahmed M Al Kersh², Mohamed M Al Sherif¹
¹ Department of Cardiology, Faculty of Medicine, Menoufia University, Menoufia, Egypt
² Department of Cardiology, Nasser Institute Hospital, Cairo, Egypt

Date of Submission	13-Apr-2014
Date of Acceptance	09-May-2014
Date of Web Publication	18-Oct-2016

Correspondence Address:
Mohamed M Al Sherif
32El Emam AbouHanifa, 7^th District, Nasr City, Cairo, 11759
Egypt

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/1110-2098.192450

Abstract

Objectives:
The purpose of this study was to evaluate the differences in the extent of coronary atherosclerosis in patients with (type I and type II) diabetes as compared with patients without diabetes by multislice computed tomography calcium scoring and its effect on the patency of coronary arteries in patients referred for multislice computed tomography.
Background:
The calcium score is an important method for the assessment of coronary atherosclerosis.
Participants and methods:
This study was conducted on 90 patients: 30 of them with known type I diabetes mellitus (DM) (on insulin), 30 patients with type II DM (on oral treatment) and the other 30 participants without DM.
Results:
Results of the current study showed that the calcium score was significantly higher among patients with DM than among controls (P < 0.005). Results also showed that the mean number of affected vessels was significantly higher among the studied patients than among the controls (P < 0.001).The percentage of obstructive lesions was significantly higher among the studied patients than among controls (P < 0.026).
The calcium score was significantly higher among diabetic patients with obstructive lesions in comparison with diabetic patients with nonobstructive lesions (P < 0.001).
Conclusion:
The calcium score is an accurate method for determining the presence and the extent of coronary atherosclerosis, especially in patients with DM.
The calcium score was significantly higher among patients with DM than among controls. The mean number of affected vessels and the percentage of obstructive lesions was significantly higher among the studied patients than among controls.
The calcium score was significantly higher among diabetic patients with obstructive lesions in comparison with diabetic patients with nonobstructive lesions.

Keywords: calcium score, coronary atherosclerosis, diabetes mellitus (type I and II)

How to cite this article:
Reda AA, Al Kersh AM, Al Sherif MM. Extent of coronary atherosclerosis in diabetic and nondiabetic patients by multislice CT calcium scoring. Menoufia Med J 2016;29:437-42

How to cite this URL:
Reda AA, Al Kersh AM, Al Sherif MM. Extent of coronary atherosclerosis in diabetic and nondiabetic patients by multislice CT calcium scoring. Menoufia Med J [serial online] 2016 [cited 2023 Oct 2];29:437-42. Available from: http://www.mmj.eg.net/text.asp?2016/29/2/437/192450

Introduction

At present, 200 million people have diabetes mellitus (DM) worldwide, while its prevalence is expected to continue increasing exponentially ^[1].

A close relationship between type 2 diabetes and the development of coronary artery disease (CAD) exists and cardiovascular disease is the main cause of death in this patient population ^[2].

Cardiovascular disease and CAD in particular constitute a major cause of morbidity and mortality in patients with diabetes ^[3].

However, the management of this patient population remains challenging. Current European guidelines regard type II diabetes as a CAD equivalent, whereas type I diabetes is considered as a high-risk state only in the presence of microalbuminuria. In contrast, US guidelines on primary prevention recommend stringent pharmacological therapy with lipid and blood pressure goals comparable to those in secondary prevention for all diabetic patients regardless of the type of diabetes ^[4].

Multislice computed tomography (MSCT) can noninvasively and accurately detect coronary calcification, which is a predictor of ischemic heart disease. Plaque calcifications usually precede luminal narrowing and the onset of angina symptoms. The sensitivity and the specificity of MSCT for the detection of stenosis have been reported to be >90 and >50%, respectively ^[5].

The higher event rates in patients with diabetes as compared with patients without diabetes could be related to differences in the coronary plaque burden; therefore, direct visualization of coronary plaque burden could be a useful tool for risk stratification ^[6].

The atgerisclerosis event rates are observed equally in diabetic patients as compared with nondiabetic individuals indicating a need for further refi nement of prognostication in this population ^[4].

To date, atherosclerosis has been assessed noninvasively in patients with diabetes using coronary artery calcium scoring, revealing extensive atherosclerosis ^[7].

Hence, the aim of this study was to evaluate the differences in the extent of coronary atherosclerosis in patients with type I and type II diabetes as compared with patients without diabetes by MSCT calcium scoring and its effect on the patency of coronary arteries in patients referred for MSCT.

Participants and Methods

Inclusion criteria: this study was conducted on 90 patients: 30 of them with known type I DM (on insulin), 30 patients with type II DM (on oral treatment) and another 30 participants without DM.

Exclusion criteria: patients with any concomitant valvular or congenital heart disease, end-stage renal or hepatic impairment, patients who had a history of stent placement or coronary artery bypass surgery and patients with known allergic reactions were excluded from the study.

Written informed consent was obtained from all patients included in the study. All patients included were subjected to full history taking. Whether the patient was diabetic or not and the drug used for the treatment of diabetes were noted. Complete general, local examination of the heart and chest, ECG, echo-Doppler study, lipid profile and serum creatinine were performed.

Echocardiographic study

Full M-mode, 2-D and Doppler echocardiographic studies were performed on all patients included in the study using a GE vivid III echocardiography machine

(Providian Medical Equipment LLC. 5335 Avion Park Dr. Unit A Highland Heights, OH 44143).

CT data acquisition and postprocessing

For each case, an ECG-gated scan without the use of contrast was performed prospectively from the aortic bulb to the tip of the heart with a 64-section CT scanner (Toshiba Aquilion 64, 9740 Irvine Blvd., Irvine, CA 92618) at a single breath-hold and at a slice thickness of 3 mm on the basis of previous electron beam computed tomography (EBCT) studies ^[8]. A medium sharp reconstruction filter kernel without edge enhancement was chosen to provide moderate image noise.

Images were collected and processed by the Vitrea software (Toshiba Medical Systems Europe B.V. Zilverstraat 1 2718RP Zoetermeer The Netherlands) to assess calcium in all coronary vessels and to calculate the calcium score by the Agatston score system ^[9].

Patients were scanned with a 64-section CT scanner (Toshiba Aquilion 64). The scanning range covered the entire heart from the level of the aortic bulb to the tip of the heart. An 80 ml bolus of iodixanol (Visipaque 320, GE Healthcare Ireland Cork, Ireland), followed by 80 ml of saline solution, was continuously injected into an antecubital vein through an 18–20 G catheter at an injection rate of 5 ml/s. Contrast agent administration was controlled by means of bolus tracking. One radiologist placed a region of interest, and image acquisition started 5 s after the signal attenuation reached the predefined threshold of 140 HU.

Data were acquired in a craniocaudal direction with a section collimation of 64×0.6 mm, a gantry rotation time of 370 ms, a tube voltage of 120 kV and a tube current of 650–780 mAs. The ECG was digitally recorded during data acquisition and was stored with the unprocessed CT data set.

CT data sets that were synchronized to the ECG data were reconstructed retrospectively from 20 to 80% of the R-R interval in 5% steps for each patient. The adaptive cardiac volume approach was used for image reconstruction; this approach automatically switches between one-segment and two-segment reconstructions depending on the patient's heart rate. Images were reconstructed with a section thickness of 0.6 mm. The field of view was adjusted to encompass the heart exactly (mean field of view, 154 ± 17 mm; range, 129–180 mm). All coronary segments were studied at 75 and 40% of the cardiac cycle, with selective reconstruction of the improperly visualized coronary segments at different phases of the cardiac cycle.

After patient and ECG information were obtained, all reconstructed images were transferred to a dedicated workstation (Vitrea), where axial images and multiplanar coronal, sagittal and curved MPR images were collected and processed to assess all coronary segments (course, patency and luminal study) to determine whether lesions were present and, if present, whether they were obstructive or not (obstructive lesions are defined as those with more than 70% stenosis and nonobstructive lesions as those with less than 70% stenosis (from 10 to 50% stenosis).

CT was performed successfully in all patients without complications. The CT protocol was well tolerated by all patients and all were able to hold their breath during data acquisition.

Statistical analysis

Data of all patients were collected and fed to the computer and analyzed using statistical package SPSS for PC version 16.5 (IBM Corporation, Armonk, New York, United States). Descriptive statistics were performed using mean and SD for continuous variables and percentage for categorical variables. Nonpaired Student's t-test was used to determine the presence of significant differences between groups in continuous variables. The c ²-test was used to determine the presence of significant differences between groups in categorical variables ^[0]. The Pearson correlation coefficient was used to determine the presence of a significant correlation between diabetes, coronary atherosclerosis and the different parameters. P less than 0.5 was considered significant with a confidence interval of 95%.

Results

This study was conducted on 90 patients referred for MSCT. They were divided into three groups: group I included 30 nondiabetic patients referred for MSCT as the control group; group II included type I DM patients (on insulin); and group III included another 30 type II DM patients (on oral treatment).

[Table 1] shows that the mean age of the studied patients was 56.3 ± 8.2 years in group II and 58 ± 10.1 years in group III; the weight was 89.7 ± 10.3 in group II and 89.2 ± 16.7 in group III; the height was 167.8 ± 5.4 in group II and 162.5 ± 28.6 in group III; the pulse was 63 ± 4 in group II and 65 ± 4 in group III; the systolic blood pressure (SBP) was 111.6 ± 11.9 in group II and 111.6 ± 11.9 in group III; the diastolic blood pressure (DBP) was 64.6 ± 6.8 in group II and 64.6 ± 6.8 in group III; the coronary artery calcium score (CACS) was 2 ± 81 in group II and 123 ± 237 in group III.

Table 1: Results of general examination and CACS of patients and controls in the study

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In the control group, the mean age was 57.2 ± 11.8 years, the weight was 88.3 ± 9.1, the height was 169.4 ± 6.6, the pulse was 62 ± 5, the SBP was 111.6 ± 11.9, the DBP was 64.6 ± 6.8 and the CACS was 3 ± 84.

There was no significant difference between the three groups regarding their age, weight, height, pulse SBP and DBP (P > 0.05). However, there was a significant difference between the three groups with regard to CACS (P<0.001).

[Table 2] shows that the number of individuals with nonaffected vessels was 16 in group II and 20 in group III, whereas the number of individuals with more than one affected vessel was 14 in group II and 10 in group III.

Table 2: The number of affected vessels was significantly higher in group II than in group III, which was significantly higher than in group I

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In the control group, the number of individuals with nonaffected vessels was 24, whereas the number of individuals with more than one affected vessel was 6.

The number of affected vessels was significantly higher in group II than in group III, which was significantly higher than in group I (P<0.001).

[Table 3] shows that there were seven individuals with normal coronaries in group II and 14 individuals with normal coronaries in group III; also, there were nine individuals with nonobstructive lesions in group II and six individuals with nonobstructive lesions in group III; there were 14 individuals with obstructive lesions in group II and 10 individuals with obstructive lesions in group III.

Table 3: Obstructive lesions were significantly higher among diabetic patients than among nondiabetic patients

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In the control group, there were 20 individuals with normal coronaries, four individuals with nonobstructive lesions and six individuals with obstructive lesions.

The obstructive lesion was significantly higher among diabetic than among nondiabetic patients.

[Table 4] shows that the calcium score of obstructive lesions was 879 ± 563 and the calcium score of nonobstructive lesions was 121.6 ± 235.8.

Table 4: The calcium score was significantly higher among diabetic patients with obstructive lesions in comparison with diabetic patients with nonobstructive lesions

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The calcium score was significantly higher among diabetic patients with obstructive lesions in comparison with diabetic patients with nonobstructive lesions.

[Figure 1] shows that the number of affected vessels was 14 in group II and 10 in group III, whereas the percent of affected vessels was 46.6 in group II and 33.3% in group III.

Figure 1: The number and percent of affected vessels in the three groups.

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In the control group, the number of affected vessels was 6, whereas the percent of affected vessels in group I was 20%.

Hence, the mean number of affected vessels was significantly higher among the studied patients than among controls.

[Figure 2] shows that the calcium score of obstructive lesions was 879 ± 563 and the calcium score of nonobstructive lesions was 121.6 ± 235.8.

Figure 2: The calcium score of the obstructive and the nonobstructive lesions in diabetic patients.

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The calcium score was significantly higher in diabetic patients with obstructive lesions than in diabetic patients with nonobstructive lesions.

Discussion

In this study, we evaluated the relationship between coronary artery calcium scoring and the extent of atherosclerosis. The study was conducted on thirty nondiabetic patients referred for MSCT, enrolled as the control group, thirty type I diabetic patients (on insulin) and thirty type II diabetic patients (on oral treatment). In this study, we used the Agatston calcium scoring as the evaluation method of calcium scoring.

Results of the current study show that the calcium score was significantly higher among patients with DM than among controls.

The results of the current study are in agreement with the results of other researchers ^[10],[11], who have documented that patients with diabetes have a higher prevalence and extent of coronary calcium than nondiabetic patients.

Other researchers ^[2] have studied the prevalence of significant coronary calcium score in patients with diabetes. They evaluated calcium in the coronary arteries of 139 consecutive diabetic patients and compared the calcium score with a randomly selected nondiabetic control group. They found that patients with diabetes had a significant increase in the prevalence of coronary artery calcification (CAC) scores greater than 400 compared with the randomly selected and matched nondiabetic control groups.

Our results disagreed with that reported in the South Bay Heart Watch Study who found that the baseline coronary calcium predicted risk in the nondiabetic subgroup, but not in the diabetic subgroup. They included 269 asymptomatic individuals and evaluated the calcium score in these patients, but they used EBCT, which may be the cause for the difference between the results of their study and our study ^[3].

Results of the current study demonstrated that diabetic patients are at a higher risk than nondiabetic patients, and this hypothesis is confirmed by Greenland et al. ^[4], who demonstrated that intermediate-risk patients with an elevated clinically significant (CS) score had an annual hard event rate of 2.8% or a 10-year rate of 28%, and thus would be considered as high risk.

Also, patients with diabetes are considered to be in the highest risk category according to the Adult Treatment Panel III guidelines (2001), consistent with the observation that diabetic patients have a high burden of atherosclerosis; asymptomatic diabetic patients without known CAD have a prevalence of CAC similar to nondiabetic patients with obstructive CAD ^[5]. Diabetic patients without any evidence of coronary calcium have a survival rate similar to that of nondiabetic patients, with a zero calcium score during 5 years of follow-up ^[1].

Our results disagree with that reported by Selvin et al. ^[6], who reported that there was no difference in CAC scores or in the prevalence of coronary atherosclerosis in patients with type 1 and type 2 diabetes; however, the prevalence of obstructive atherosclerosis was higher in patients with type 2 diabetes than in patients with type 1 diabetes.

We found that the mean number of affected vessels was significantly higher among the studied patients than among controls (P<0.001). Also, the percentage of obstructive lesions was significantly higher among the studied patients than among controls (P<0.001). The results showed that the calcium score was significantly higher among diabetic patients with obstructive lesions in comparison with diabetic patients with nonobstructive lesions (P<0.001).

Our results are in agreement with the theory that negative CS indicates that the presence of significant luminal obstructive disease is highly unlikely. A zero score is associated with a low risk of a cardiovascular events in the next 2–5 years ^[7]. Our results are also in agreement with reports that coronary calcium scanning shows a very high negative predictive value: an Agatston score of 0 has a negative predictive value of nearly 100% for ruling out a significant coronary narrowing ^[8].

In the study of Budoff et al. ^[7], out of 710 enrolled patients, 427 had significant angiographic disease and coronary calcium was detected in 404, yielding a sensitivity of 95%. Of the 23 patients without calcium, 83% had single-vessel disease on angiography. Of the 283 patients without angiographically significant disease, 124 had negative EBCT studies. This is a reminder of the possibility of missing patients with CAD when the CS is low.

The present study indicates that calcium scoring is an integral part of the evaluation of patients referred for MSCT. Calcium scoring is a more sensitive noninvasive tool for the assessment of CAD. In patients with high calcium scoring, significant CAD is suspected. The correlation between calcification with MSCT and angiography is needed. Patients with calcium score greater than 1500 should undergo coronary angiography. A large number of patients should be included in further studies to assess the relation between calcium scoring, diabetes and the severity of CAD.

Conclusion

Calcium score scanning is an accurate and noninvasive method of determining whether or not underlying atherosclerotic CAD is present, especially in patients with DM. It also provides an estimate of the extent and the severity of coronary disease. The calcium score was significantly higher among patients with DM than among controls. The mean number of affected vessels was significantly higher among the studied patients than among controls.

The percentage of obstructive lesions was significantly higher among the studied patients than among controls. The calcium score was significantly higher among diabetic patients with obstructive lesions in comparison with diabetic patients with nonobstructive lesions.

The calcium score was significantly higher among nondiabetic patients with obstructive lesions in comparison with nondiabetic patients with nonobstructive lesions.

Further studies are needed to assess the relation between calcium scoring and the severity of CAD.

Acknowledgements

Concept of this study was given by Dr. Ahmed Ashraf Reda; design of the study: Dr. Ahmed Ashraf Reda and Dr. Ahmed Mokhtar Al Kersh; definition of intellectual content: Dr. Ahmed Mokhtar Al Kersh; literature search: Dr. Mohamed Al Sherif; clinical studies: Dr. Mohamed Al Sherif; experimental studies: Dr. Mohamed Al Sherif; data acquisition: Dr. Ahmed Mokhtar Al Kersh; data analysis: Dr. Ahmed Mokhtar Al Kersh; statistical analysis: Dr. Ahmed Mokhtar Al Kersh and Dr. Ahmed Ashraf Reda; manuscript preparation: Dr. Ahmed Mokhtar Al Kersh and Dr. Mohamed Al Sherif; manuscript editing: Dr. Ahmed Ashraf Reda and Dr. Ahmed Mokhtar Al Kersh; manuscript review: Dr. Ahmed Ashraf Reda.

Conflicts of interest

There are no conflicts of interest.[18]

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