A Prospective Study of 477 Subjects through Risk Stratification and Corroboration by a Non-Invasive CT Coronary Angiogram in a Tertiary Hospital Setting in India
Received Date: Oct 29, 2018 / Accepted Date: Nov 24, 2018 / Published Date: Nov 28, 2018
Coronary artery disease (CAD) is a very common cause of morbidity and is the leading cause of death in adults, accounting for one-third of all deaths in subjects over age 35. Catheter coronary angiography (CCA) has been the gold standard in the diagnosis and management of CAD. Over the last few years, Coronary CT angiography (CCTA), a non-invasive test is being adopted by positive evidence and usability for low-medium pre-test probability for CAD.
Keywords: Smoking; Mortality; Coronary heart disease; Cardiovascular risk
Timely recognition of population at high risk of cardiovascular events is the cornerstone of cardiovascular disease prevention and a challenge for healthcare worldwide. The Framingham risk score, QRISK and Systemic Coronary Risk Evaluation (SCORE) have been some of the most validated risk algorithms in predicting cardiovascular events to determine how risk might change with modification of risk factors such as weight loss, smoking cessation, use of statins and better blood pressure control. The risk estimates are also well documented and correlated with carotid intima-media thickness (CIMT) and coronary calcium score (CCS)- the two well established measures of subclinical atherosclerosis and reliable predictors of future risk of CV events.
In the light of the above, the objective of our study was targeted to collect, analyse and decipher the Cardiac risk scores using our devised weighted average tool and thereby ramify to utilize the CT Coronary Angiogram cost-effectively, in a resource-limited country setting. The rationale and effectiveness of CCTA is in direct visualisation of the coronary artery lumen and wall in the assessment of Coronary artery disease.
1320 subjects were screened, and a Cardiac risk profiling were done in a 6 months study period in 2016. Traditional risk factors for CAD like hypertension, dyslipidaemia, diabetes, obesity, smoking, family history of CAD etc. were mapped out. A weighted average risk stratification tool was devised to stratify suspected CAD groups and to thereby clinically corroborate using CT Angiogram. 477 (36%) underwent 320 slice Coronary CT Angiogram including the asymptomatic subjects. Patients were classified as (a) normal (no calcific or soft plaque), (b) thick plaque and moderate CAD (<50% stenosis), (c) obstructive coronary disease (>50% stenosis) (Figure 1 and Table 1).
|Risk stratification tool - Baseline data|
|Traditional risk factors for cardiac events (Non-discrete multiple co-morbid data in 477 subjects)||N||% of 477|
|Atypical Chest Pain||54||11|
|Status Post CABG/PTCA||78||16|
|TMT (Treadmill) Positive/Borderline||55||12|
Table 1: Baseline clinical characteristics of 477 subjects: Non-discrete multiple comorbid risk factors.
316 (66%) were males and 161 (34%) were females. Mean age was 55.6 ± 8.3 years. 199 (42%) cases were found to have normal coronary arteries on CCTA, 278 (58%) of the subjects had an abnormal CT angiogram finding of which 78 (16.3%) were status post Percutaneous Interventions/Coronary Artery bypass surgeries reviewed for graft patency. Out of these 78 cases, 28 (35.9%) had graft or the native vessel occlusion after a median follow up of 8.2 years after the CABG/PTCA by this CCTA (Figure 2).
3 risk factors (hypertension, diabetes and dyslipidaemia) present in 39 (95%) cases had abnormal CT Angiogram of the total 41 cases. 2 risk factors (hypertension, diabetes or dyslipidaemia) resulted in 87 (31.3%) cases of 278 abnormal CT Angio findings arm versus 62 (31.1%) of 199 normal CT Angio findings. This is statistically significant (p<0.01) and clinically significant to infer that 3 risk factors pose a great threat to cardiovascular risk and predictors of risk are long duration and uncontrolled comorbid conditions.
Smoking is a risk factor for mortality and coronary heart disease in hypertension and in diabetes and the absolute risk of smoking is usually greater in diabetic subjects than in nondiabetic subjects [1-3]. Smoking was found in 14 (3%) of the cases which is grossly underreported by subject’s declaration for risk scoring.
Coronary calcium score zero was found in 236 (59%) out of the 399 cases (n=78 post CABG and post PTCA cases excluded). Coronary calcium score (>100) in 73 (18%) in the abnormal CT angio arm versus 3 (0.7%) in normal CT Angio arm (Table 2).
|Total - 399 subjects||0||0-10||10-100||<100||100-399||>400|
|CAC Score in Normal CT Angio findings subjects||178||16||16||210||2||1|
|CAC Score in Abnormal CT Angio findings subjects (primary prevention arm)||58||20||34||113||34||38|
Table 2: Coronary calcium score in Indian subjects, n= 399, 78 cases of post CABG and post PTCA cases excluded.
Of the total 278 abnormal CT Angio, mild CAD was noted in 121 (44%), thick plaque (<50% stenosis) noted in 59 (21%), obstructive CAD (>50% stenosis) were noted in 98 (35%) cases. Double vessel disease was seen in 156 (56%) cases and single vessel disease was seen in 108 (39%). Significantly obstructive triple vessel disease was noted in 14 (5%) of total cases (Figure 3).
58 (12%) of the subjects who had a CCTA, were less than 40 years old of which 18 (31%) had a CAD, 12 (66%) were soft and thick plaque whereas 6 (33%) had obstructive coronary artery disease (>50% stenosis). Right coronary artery dominant was found in 383 (80%), left dominant in 79 (17%) and co-dominant in 14 (3%) of the total cases.
Congenital Heart Disease (ASD/VSD) were found in 7(1%) of the cases. Left Ventricular Hypertrophy in 31 (6%) of the cases as other CCTA findings. The non-ionic contrast usage was 65ml in 386 (81%) and 70 ml in 83 (17.3%) of the total 477 cases.
Health economics and cost-effective disruptive screening programs are in vogue and risk stratification tools may add a lot of impact in enhancing the pick-up of disease burden rates precisely and accurately and thereby better patient deliverables. QRISK3 is a prediction algorithm for cardiovascular disease (CVD) that uses traditional risk factors and to also estimate individualised lifetime risk of cardiovascular disease .
Primary prevention of Coronary artery disease is extremely crucial and deciphering the population at large with risk categorization and management will potentially prevent or reduce the severity of dreadful cardiac events and complications.
CAC score to predict CAD in our Indian study had 96% sensitivity, 65% specificity with a positive predictive value of 39% and a negative predictive value of 98.5%. Considering ASCVD risk estimates and CAC Score together, can provide valuable insights to decide the management plan to initiate Statins or not .
Risk profiling and stratification may be a valuable tool which may correlate with CT angio findings. Hypertension, Dyslipidaemia and Diabetes as 3 co-existing risk factors contribute to a large extent of CVD burden One third having abnormal CT Coronary Angiogram findings in age groups of <40 years suggestive of Coronary artery disease from this study, a decade/few decades early shift of cardiac events in population, is quite alarming.
Conflicts of Interest
There are no conflicts of interest for the present study.
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Citation: Gomadam SS, Yogeeswari VS, Rajasree S, Gani A (2018) A Prospective Study of 477 Subjects through Risk Stratification and Corroboration by a Non-Invasive CT Coronary Angiogram in a Tertiary Hospital Setting in India. J Cardiovasc Dis Diagn 6: 346. DOI: 10.4172/2329-9517.1000346
Copyright: © 2018 Gomadam SS, et al. This is an open-access article distributed under the terms of the creative commons attribution license, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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