Prevalence of carotid artery stenosis in ischaemic heart disease patients in Bangladesh

Introduction

Approximately 30% of all cases of global mortality are due to cardiovascular diseases, and only 10% are due to cerebrovascular disease. ¹ Among these, the major risk factors are hypertension, smoking, increased blood lipid profile, and diabetes. Moreover, these factors play a part in the pathogenesis of cardiovascular disease and in its treatment prognosis. ² Carotid stenosis is an associated factor for perioperative ischaemic stroke in patients undergoing myocardial revascularization surgery. ³ Ischemic heart disease patients who are undergoing surgical myocardial revascularization have significant carotid artery stenosis (CAS). ⁴ Chen et al. ⁵ observed that in carotid artery ultrasound scans of ischaemic heart disease (IHD) patients before isolated coronary artery bypass graft surgery (CABG), significant CAS (>75% stenosis) was identified in 13% of patients. In studies that examined all patients undergoing CABG, ⩾50% CAS was detected in approximately one-third of study patients. ⁶ The proportion of CAS (⩾50% stenosis) in CABG patients in Western countries increased from 12.8% to 22%. However, the prevalence of significant CAS (>70% stenosis) ranged from 7% to 11% in IHD patients. ⁷

A current meta-analysis study of CAS and stroke after CABG observed that the probability of perioperative stroke ranges from 2% to 7%. ⁸ A survey found that the prevalence of ⩾50% CAS was 25.4% in a Japanese study population, and the prevalence of CAS in CABG cohort was 23.9% in Korean patients. ⁹ In China, studies of concurrent IHD and carotid artery disease (CAD) patients showed that only 2% patients had ⩾50% carotid stenosis involving common carotid arteries, while the rate was higher in case of internal carotid artery involvement.^10,11 It was recommended that all Japanese CABG patients undergo the preoperative CAS screening regardless of age. ¹¹ Recent European and American CABG guidelines recommend CAS screening among the patients who are ⩾65 and ⩾70 years of age. ¹² In previous studies of CABG of the patients who suffered from 50% to 80% CAS, the incidence for ischaemic stroke varied from 3% to 10%, and the incidence was higher, approximately 22%, among the patients having ⩾80% carotid stenosis. ¹³

There are some independent risk factors of significant CAS, especially age, sex (female sex), hypertension, dialysis, prior stroke, left main coronary artery disease, and peripheral vascular disease (PVD). Several studies have found that there is an increased risk of significant neurological deficits in IHD patients who also have significant CAS and are undergoing CABG using cardiopulmonary bypass.^8–15 The aim of this study was to investigate the current proportion and to determine the associated risk factors of CAS in IHD patients.

Patients and methods

This cross-sectional study was carried out among patients with a history of IHD at the Department of Cardiac Surgery, Bangabandhu Sheikh Mujib Medical University, Shahbagh, Dhaka, Bangladesh, from July 2017 to June 2018. Ethical clearance for the study was granted from the relevant departmental academic and technical committee. All patients enrolled in this study were briefed about the nature and the purpose of the study and about the questionnaire to be used for the study. An informed written consent was collected from all the participants. Patients with coronary artery disease scheduled for isolated CABG were included in the study. Patients with coexisting valvular heart disease, congenital heart disease, or emergency CABG were excluded. Haemodynamically unstable patients were also excluded.

Convenience purposive sampling techniques were used to include all available respondents based on recently published paper. ¹² Investigational findings including duplex study of neck vessels and blood sampling were also included. A standardized semi-structured data collection sheet was used to collect necessary information on the study subjects, and grading of CAS (mild < 50% lesion, moderate 50%–70% lesion, severe > 70% lesion) done depending on recent Gray-Scale and Doppler US Diagnosis criteria by Society of Radiologists in Ultrasound Consensus Conference. ¹⁵ All relevant data were collected from each respondent by use of interviews, measured parameters and investigations in a predesigned format.

Result

This study evaluated sociodemographic variables of the study population and observed that a majority of (72.0%) the patients were 50–59 years of age and 28.0% of patients were 60–70 years of age. The mean age was 57.7 ± 3.06 years, and approximately 70% of patients were male. About one-third of patients were service workers (31.5%) or businessmen (28.0%), while 16.5%, 12.0%, and 12.0% of patients were housewives, farmers, and teachers, respectively. Most of the patients (74.5%) were Muslim, 16.0% were Hindu, 5.0% were Buddhist, and 4.5% were Christian. Furthermore, only 36.5% patients were university graduates. A majority of patients (59.0%) were overweight or obese (34.5%). The mean body mass index (BMI) of the overall respondents was 29.57 ± 4.51 kg/m². Regarding demographic characteristics, age and sex were not statistically significantly associated with the extent of CAS. However, severe and moderate CAS was significantly higher in obese patients (Tables 1 and 2).

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Table 1.

Socio-demographic characteristics of the study patients.

Socio-demographic characteristics	Frequency	Percentage
Age group (years)
50–59	144	72.0
⩾60	56	28.0
Mean ± SD	57.7 ± 3.06
Sex
Male	136	68.0
Female	64	32.0
Occupation
Businessman	56	28.0
Farmer	24	12.0
Housewife	33	16.5
Service worker	63	31.5
Teacher	24	12.0
Religion
Muslim	149	74.5
Hindu	32	16.0
Buddhist	10	5.0
Christian	9	4.5
Educational status
Primary	24	12.0
SSC	42	21.0
HSC	33	16.5
University graduate	73	36.5
Masters	28	14.0
BMI level (kg/m2)
Normal weight	13	6.5
Overweight	118	59.0
Obese	69	34.5
Mean BMI (kg/m2)	29.57 ± 4.51

SD: standard deviation; BMI: body mass index.

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Table 2.

Association of demographic characteristics with carotid artery stenosis based on Duplex scan.

Demographic data	Mild stenosis (n = 164)		Moderate stenosis (n = 24)		Severe stenosis (n = 12)		p value
	N	%	N	%	N	%
Age (years)
50–59	120	73.2	15	62.5	8	66.7	0.518ns
⩾60	44	26.8	9	37.5	4	33.3
Sex
Male	110	67.1	16	66.7	10	83.3	0.501ns
Female	54	32.9	8	33.3	2	16.7
Body Mass Index (BMI)
Normal weight	13	7.9	0	0.0	0	0.0
Overweight	115	70.1	1	4.2	2	16.7	<0.001s
Obese	36	22.0	23	95.8	10	82.3

n: number of subjects; ns: not significant; s: significant.

Mild stenosis ⩽50% lesion, moderate stenosis = 50%–69% lesion and severe stenosis ⩾70% lesion. The percentage of carotid lesion was calculated from the Carotid Duplex Scan findings. Mild carotid stenosis indicates clinically insignificant lesion.

A chi-square test was performed to determine the association; p values ⩽0.05 were considered statistically significant.

Most of the study patients (82.0%) had insignificant (mild) CAS (<50% stenosis). However, 18% of patients had significant moderate (50%–69% stenosis) or severe (>70% stenosis) CAS. Furthermore, approximately 80% of patients had unilateral CAD among the significant CAS population. Most patients (71.5%) had triple or more coronary artery disease associated with risk factors such as hypertension (58.0%), diabetes mellitus (20.0%), and hyperlipidaemia (5.0%); 17.0% of patients had multiple risk factors. Regarding risk factor analysis, severe (>70% stenosis) and moderate (50%–69% stenosis) CAS were significantly associated with all of the above risk factors. Moreover, triple vessel or greater coronary artery disease was also significantly associated with the severity of CAS (Table 3).

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Table 3.

Association of carotid artery stenosis with associated factors and number of carotid artery involvement.

Variables	Mild stenosis (n = 164)		Moderate stenosis (n = 24)		Severe stenosis (n = 12)		p value
	N	%	N	%	N	%
Risk factors
Hypertension	113	68.9	3	12.5	0	0.0	<0.001s
DM	38	23.2	1	4.2	1	8.3	0.054s
Hyperlipidaemia	8	4.9	1	4.2	1	8.3	0.852
Multiple comorbidity	5	3.0	19	79.2	10	83.3	0.618
Coronary artery involvement
Single vessel	7	4.3	3	12.5	0	0.0	0.187
Double vessel	47	28.7	0	0.0	0	0.0	0.001s
Triple or more	110	67.1	21	87.5	12	100.0	0.004s
Number of the carotid artery stenosis
Bilateral	7	4.3	22	91.7	12	100.0	<0.001s
Unilateral	157	95.7	2	8.3	0	0.0

DM: diabetes mellitus; n: number of subjects; s: significant.

A chi-square test was performed to determine the association, and p values ⩽0.05 were considered statistically significant.

Discussion

This retrospective study demonstrated the severity of CAS associated with majority male (70%) elderly patients with a mean age of 57.7 ± 3.06 years. A total of 59.0% patients were overweight, and severe CAS was significantly higher in obese patients. In patients with severe CAS, the proportion of patients with hypertension and diabetes mellitus was higher. Furthermore, there was a significant association between bilateral CAS (>50% lesion) with the severity of coronary artery disease.

A cross-sectional study was conducted by Kayani et al. ¹⁵ at the Rawalpindi Institute of Cardiology, where 140 patients were evaluated with mean age of 59.6 ± 7.1 years. However, 56.6% of patients had insignificant CAS (<50% lesion), while 10.7% of patients had significant carotid stenosis (>50% lesion), and only 8.5% of patients had critical (>70% lesion) carotid stenosis. ¹⁵ The 2011 European peripheral artery disease (PAD) strategies extended their recommendation for preoperative duplex scan for CAS in CABG patients to include patients more than 70 years of age or those with evidence of carotid bruit, multi-vessel CAD, cerebrovascular disease, or PAD class I evidence. ¹⁶ DaRosa et al. ¹⁷ noted that the perioperative risk of stroke after cardiac surgery was 3.8%–7.4% among the patients with more than 50% CAS; moreover, they reported increasing prevalence with more than 70% carotid lesion, which is similar to our study results. In a retrospective cohort of 1558 Chinese patients who underwent CABG, the prevalence of CAS with ⩾50% and ⩾70% stenosis were 21.2% and 6.7%, respectively. ¹⁸ The incidence of perioperative stroke among CABG patients was remarkably higher in study patients having severe or significant CAS, which is also concordant with other articles.^15,18–20

In Bangladesh, a study by Ranjan et al. ²¹ observed that the majority (46.66%) of patients had significant (75%–90%) CAS associated with complex coronary artery disease. Moreover, approximately 40% of patients experienced right-sided, though 53.33% experienced left-sided and only 6.66% had bilateral carotid endarterectomy in Bangladesh, which is also similar to this study. ²¹ However, Fukuda et al. observed that the prevalence of severe carotid stenosis (>70%) to be 4.1%–13.3% which also remains in concordance with other study findings.^22,23 Furthermore, study by Durand et al. also identified elderly age, female gender, PVD, prior stroke, left main coronary disease, multi-vessel CAD, hypertension, and DM as risk factors associated with significant carotid artery lesion, which is also similar to other published articles.^{15,18,20–25}

This study also similarly observed that these risk factors are the strongest predictors of CAS in association with IHD. Patients with concurrent carotid artery and coronary artery disease were demonstrated to have an advanced stage of atherosclerosis involving multiple vascular systems. The occurrence of CAS in patients with IHD disease is more frequent, especially with multi-vessel coronary artery disease. This study investigated several sociodemographic variables and clinical risk factors that are pathognomonic for atherosclerosis, which might demonstrate the necessity for preoperative carotid artery screening in patients undergoing isolated CABG.

Limitations of the study

Conclusion

Multi-vessel coronary artery disease patients, especially elderly patients, are frequently associated with significant CAS. Routine carotid artery screening will identify these high-risk patients and may reduce the risk of perioperative stroke if properly managed with either concurrent or staged carotid procedure along with CABG.