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14MEDICAL SCIENCES
CORRELATION OF RAISED CARDIAC TROPONIN I (50 FOLDS UPPER LIMIT OF NORMAL) AND ELEVATED SYNTAX SCORE FOR EXTENT AND SEVERITY OF CORONARY ARTERY DISEASE IN FIRST ATTACK OF NSTEMI IN BANGLADESHI POPULATION
Khan Mahmood Hasan,
MD (Cardiology), Junior Consultant, Department of Cardiology, United Hospital Limited, Dhaka, Bangladesh Asif Rahmat Ullah,
MD (Cardiology), Junior Consultant, Department of Cardiology, United Hospital Limited, Dhaka, Bangladesh Haque Ziaul S.M.,
MPH, Senior Medical Officer, Department of Cardiology, Salalah Heart Center, Salalah, Oman
Ahmad Tanveer,
MD (Cardiology), Junior Consultant, Department of Cardiology, United Hospital Limited, Dhaka, Bangladesh Chakraborty Soumen MD (Cardiology), Junior Consultant, Department of Cardiology, United Hospital Limited, Dhaka, Bangladesh.
Rahman Reazur,
D-Card, Associate Consultant, Department of Cardiology, United Hospital Limited, Dhaka, Bangladesh
Nahar Samsun,
FCPS (Medicine) MD (Cardiology), Associate Consultant, Department of Cardiology, United Hospital Limited, Dhaka, Bangladesh
Shafique A.M.,
MD (Cardiology), Consultant, Department of Cardiology, United Hospital Limited, Dhaka, Bangladesh
Bala Poppy,
MD (Cardiology), Specialist, Department of Clinical & Interventional Cardiology, Evercare Hospital, Dhaka,
Bangladesh
Karim Aparajita,
D-Card, Senior Specialist, Department of Clinical & Interventional Cardiology, Evercare Hospital, Dhaka,
Bangladesh
Bhuiyan Azfar H.,
D-Card, Associate Consultant, Department of Clinical & Interventional Cardiology, Evercare Hospital, Dhaka,
Bangladesh
Alam Shamsul Md.,
D-Card, Associate Consultant, Department of Clinical & Interventional Cardiology, Evercare Hospital, Dhaka,
Bangladesh
Islam Nighat,
MD (Cardiology), Associate Consultant, Department of Clinical & Interventional Cardiology, Evercare Hospital, Dhaka, Bangladesh Rahman Ziaur Mohd,
MRCP (UK), MSc (Cardiology), D-Card, Specialist Registrar, Department of Cardiology, Neville Hall Hospital,
Abergavenny, Wales, United Kingdom
Siddique Atique Bin,
MRCP (UK), D-Card, Specialist Registrar, Department of Cardiology, Royal Devon and Exeter, NHS Foundation Trust, United Kingdom
Yusuf Intekhab Md.,
MRCP (UK), D-Card, Specialist Registrar, Department of Internal Medicine, George Eliot Hospital, NHS Foundation Trust, United Kingdom
Tanbir Hossain A.,
D-Card, Specialist, Department of Clinical & Interventional Cardiology, Evercare Hospital, Dhaka, Bangladesh
Zahidul Haque Md.,
D-Card, Specialist, Department of Clinical & Interventional Cardiology, Evercare Hospital, Dhaka, Bangladesh
Choudhary Walid Mohammad Mujib, MRCP (UK), Specialist Registrar, Department of Internal Medicine, George Eliot Hospital, NHS Foundation
Trust, United Kingdom Das Anjan Kumar,
D-Card, Assistant Professor, Department of Cardiology, Cumilla Medical College, Cumilla, Bangladesh
Abstract
Background: Coronary heart disease (CHD) is the single most important cause of death. Diagnosing ACS is important because the diagnosis triggers both triage and management. Cardiac Troponin-I (cTnl) known to be a very sensitive and specific marker for extent of coronary artery involvement. The objective of the Study: The study aimed to determine the correlation of extent of coronary artery disease (CAD) with elevated syntax score &Tro-ponin - I level in non- ST elevated MI (NSTEMI). Methods: This cross-sectional analytical study was conducted from July 2019 to June 2020 in the Department of Cardiology, United Hospital Limited. Total 230 first attack of NSTEMI patients was included in the study. All patients underwent coronary angiography in United Hospital Limited. Single, double or triple vessel CAD were considered for extent of CAD& syntax score <22 as low, 23 -32 as intermediate & >33 were considered as high. The sample population was divided into two groups: Group-I: Patients with first attack of NSTEMI with Troponin-I level <6.6 ng/ml. Group-II: Patients with first attack of NSTEMI with Troponin-I level >6.6 ng/ml. Association between cTnI levels and CAD extent & severity were observed statistically.Results:Out of 230 patientsof Group-I, majority (36%) had double& mean syntax score was 24.16±5.84, then 30.6% had triple vessel with mean syntax score was 34.70±8.59& the remaining had single vessel CAD with mean syntax score 14.15±5.06, whereas in patients of Group - II, most patients (46.2%) had triple vesselwith mean syntax score was 38.50±7.95, then 31.1% had double with mean syntax score was 24.70±8.59& the rest had single vessel CADwith mean syntax score 18.90±9.85. The results indicated statistically significant association between the cTnI levels and triple vessel CAD with highest syntax score (p = 0.04). Our study discovered that increased Troponin-I level over 6.6 ng/ml & elevated syntax score were a very sensitive and specific for CAD extension& severity. Conclusion: The study enabled us to conclude that, higher cTnI levels & syntax score are associated with an increased extension & severity of CAD.
Keywords: Troponin-I, Acute Coronary Syndrome (ACS), Syntax Score, Coronary Artery Disease (CAD), Sensitivity, Specificity.
Introduction
Acute coronary syndrome (ACS) used to present coronary arterial plaque disruption or frank rupture, which is possibly related to a pan-inflammatory process1, hence it is uncommon to discover non flow limiting obstruction or normal epicardial vessels in patients' coronary angiography presenting with ACS2. Level of cardiac biomarkers release has a very important prognostic value in patients with ACS3. It has been demonstrated that this subset of patients has extensive CAD compared to patients with undetectable troponins4'5. It is essential to further investigate whether the degree of increase in troponin levels in the setting of ACS equates with severe multi-vessel CAD.
Revascularization modality is still a major point of discussion between cardiac physicians and surgeons till to date. CABG & PCI with multi-vessel disease were discussed in details by different well known randomized clinical trials in patients with ACS. In earlier stage, plain old balloon angioplasty (POBA) and in later stage stenting were compared with CABG6-11 in patients with multi-vessel disease. These clinical trials clearly proved no significant difference between two treatment options regarding in-hospital outcomes but patients treated with balloon angioplasty or stenting required more often repeat revascularization procedures related to restenosis17'18.
Regarding maximal revascularization technique in patients with triple vessel and/or left main disease there are three major points to be considered:
1. To conduct a largescale study without excluding any patients.
2. Understandings between interventionists & surgeons should be present regarding treatment strategy.
3. Both the complexity of every lesion as well as number of involved coronary arteries should be taken
into account to understand the nature of severity of the lesions.
The SYNTAX (SYNergy between PCI with TAXUS™ and Cardiac Surgery) study was designed considering all patient factors with significant triple vessel CAD and/or left main disease. Patients who like to adopt any of the treatment modalities or advised for medical management were enrolled in this study.
The following classification helped to develop the SYNTAX score:
1. The AHA classification based on the ARTS study
2. The Leaman score
3. The ACC/AHA classification system
4. The total occlusion classification system
5. The Duke and ICPS classification systems.
All of these systems were focused on particular
structural and working factors of the developed lesions. Thus, the concept of a universal scoring system was taken into account.
The SYNTAX score has been developed for this study to prospectively characterize the coronary vasculature considering the involved number of coronar-ies, their importance, situation and complexity. Elevated SYNTAX score indicates more severity of the disease and is considered for a bigger revascularization challenge as well as having a worse prognosis.
In our investigation cardiac Troponin - I (cTnI) & syntax score also have been found to have excellent sensitivity and specificity and are superior to others as indicator of extent & severity of coronary artery disease.
Materials and Methods
This prospective analytical study was conducted from July 2019 to that of June 2020. Study population comprised all the patients admitted into Cardiology de-
partment with chest pain. Sample population were selected by brief history, targeted physical examination, ECG, Troponin-I level (>0.12 ng/ml) on admission and after 06 hours if the initial value was negative and on the basis of inclusion & exclusion criteria. The ethical review committee endorsed the study protocol.
A) Inclusion Criteria:
S Patients with first attack of NSTEMI.
B) Exclusion Criteria:
S Patients admitted with acute STEMI.
S Patients with congenital & structural heart disease.
S Patients had major non- cardiovascular disorder causing elevation of Troponin-I.
S Any systemic infection.
S Patients were under chemotherapy on discovery of malignancy.
S Patient not willing to get themselves enrolled in study.
Considering inclusion and exclusion criteria study population was divided into two groups17.
Group -I: Patients with first attack of NSTEMI with Troponin-I level <6.6 ng/ml.
Group -II: Patients with first attack of NSTEMI with Troponin-I level >6.6 ng/ml.
NSTEMI was defined as positive biomarkers of myocardial necrosis (troponin-I) with or without ST-segment depression in the absence of ST-segment elevation. Blood samples for cardiac troponin I were
drawn in emergency and a second sample was drawn 06 hours later if the initial sample was negative. Cardiac troponin I was determined using an immunomet-ric assay (IMA) technology. All recruited patients underwent invasive evaluation by coronary angiography in United Hospital Limited. Angiographic views were analyzed for extension of coronary artery disease. Significant CAD was defined as >70% stenosis in the major epicardial coronary arteries or a left main coronary artery stenosis >50%. Extent of CAD was considered as >70% involvement of one, two or three vessels disease. Severity of CAD was analyzed by using syntax score. Syntax score <22 as low, 23-32 as intermediate & >33 were considered as high.
The SYNTAX score is a computer based calculating system involving few self-guided questions. The system comprising of twelve questions which are divided into two arms: the first 3 defines the dominance, the lesion number & involved vessel segments. Each lesion can have one or more segments. They will be numbered anything between 1 to 12. There is no limit in the number of segments involved per lesion. The last few questions define the lesion's adverse characters. The question referring to a total occlusion is the first one. If a total occlusion is numbered, answers to be given in details. The presence or absence of side branch decide the treatment option to PCI or CABG. All the other questions of the algorithm can be answered by selecting "yes" or "no".
© && RCA
RCA
RCA
| | Patent segment ^^H Occluded segment
| | Segment distal from the occlusion filled with collateral flow (visualised by contrast)
Figure-1: Total occlusion length assessment19
a) Total occlusion involving segments 1 and 2. Segments 2,3,4,16,16a, 16b, 16c are filled by antegrade or retrograde collateral flow (visualised by contrast).
b) Total occlusion involving segments 1, 2 and 3. Segments 3,4,16,16a, 16b, 16c are filled by antegrade or retrograde collateral flow (visualised by contrast).
c) Total occlusion Involving segments 1, 2, 3, 4, 16 and 16a Segments 16,16b,16c are visualized by antegrade or retrograde collateral flow (visualised by contrast).
The last question of the algorithm, diffuse disease/small vessels, is the only one non-lesion-specific since it is related to vessel anatomy beyond the stenosis. In case of positive answer all the coronary segments beyond the one under scoring will appear allowing the selection of these fulfilling the criteria for diffuse disease/small vessels. It is quoted once (the first
time selected) per coronary territory (RCA, LM, LAD, LCX). If for example this question is answered during a LM lesion scoring it will not reappear for lesions in the LAD or LCX territory. The same is the case for multiple lesions in the same vessel. Since the lesions are scored in the numerical order inserted in question 3, a scoring in "anatomical order" from proximal to
distal is advised for each coronary artery. For example, a lesion in segment 2 of the RCA should be scored before a lesion located in more distal segments. Statistical Method and analysis: Purposive sampling was done. The collected data were calculated with computer software Statistical Package for Social Sciences version 20 (SPSS Inc., Chicago, Illinois). Quantitative data were presented as mean ± SD and Student's "t" test was used for analysis. Qualitative data were analyzed with x2 test. Comparison between groups were made by unpaired t-test. p value < 0.05 was taken as significant.
Baseline characteristics of patients according
Variables studied:
Age, Sex, Smoking, Hypertension, Diabetes Mellitus, Dyslipidemia, F/H of CAD, BMI, ECG, Troponin-I, Extent of CAD, Syntax score.
Results:
This was a Cross Sectional Analytical Study conducted in the Cardiology department of United Hospital Limited from July 2019 to June 2020. The research team tried to ascertain elevated level of Troponin-I & increased syntax score as sensitive and specific markers for extent and severity of coronary artery disease in the setting of first attack of NSTEMI.
Table-1
Variable cTnI <6.6 ng/ml (n=111) cTnI >6.6 ng/ml (n=119) p value
Age 59.40 ± 9.81 59.30 ± 12.18 0.968ns
30-44 03 (2.8%) 16 (13.4%)
45-59 54 (48.6%) 40 (33.6%)
60-74 50 (45.0%) 56 (47.1%)
75-89 04 (3.6%) 07 (5.9%)
Gender
Male 82 (73.9%) 87 (73.1%) 0.621ns
Female 29 (26.1%) 32 (26.9%)
BMI 24.65 ± 3.55 25.07 ± 4.21 0.417ns
Troponin-I level (ng/ml) 5.53±7.43 16.46±15.79 0.003s
Cardiac Risk Factors
Diabetes mellitus 55 (49.5%) 60 (50.4%) 0.595ns
Hypertension 76 (68.4%) 84 (70.5%) 0.235ns
Cigarette smoking 27 (24.3%) 37 (31.0%) 0.784ns
Positive F/H of CAD 25 (22.5%) 26 (21.8%) 0.690ns
Dyslipidaemia 78 (70.2%) 69 (57.9%) 0.294ns
cTnI means Cardiac Troponin-I, ns means not-significant, F/H means Family History, CAD means coronary artery disease.
There were 73.4% males and 26.5% females with the mean age of 59.35 ± 11.08. Among them 50% were diabetic, 69.5% were hypertensive and 63.9% were dyslipidaemic. There were 27.8% smokers and 22.2% patients had positive family H/O CAD. Mean cardiac troponin I level was 5.53±7.43 in the cTnI <6.6 ng/ml
Table- 2
Extent of coronary artery disease and number of totally occluded vessels in the study population (n=230)
group and mean 16.46±15.79 in the cTnI >6.6 ng/ml group. Patients with less troponin I level tend to be more dyslipidaemic 70.2% versus 57.9%, while patients with elevated troponin I level had a higher incidence of smoking 31.1% versus 24.3%, a higher proportion of patients age less than 45 years, 84.2% versus 15.8% and also of age greater than 75 years, 63.6% versus 36.4%.
cTnI <6.6 ng/ml (n=111) cTnI >6.6 ng/ml (n=119) p value
Extent of CAD 0.13ns
Single vessel CAD 25 (22.5%) 23 (19.3%) 0.35ns
Double vessel CAD 40 (36.0%) 37 (31.0%) 0.21ns
Triple vessel CAD 34 (30.6%) 55 (46.2%) 0.04s
Left Main Stenosis (>50%) 6 (5.4%) 12 (10.0%) 0.761ns
Branch Vessel CAD 7 (6.3%) 3 (2.5%) 0.56ns
Non-obstructive CAD 2 (1.8%) 0 (0%) 0.21ns
Normal Coronary Angiogram 3 (2.7%) 1 (0.8%) 0.34ns
Total occlusions 0.14ns
Single vessel 27 (24.3%) 40 (33.6%) 0.12ns
Double vessel 15 (13.5%) 23 (19.3%) 0.23ns
Triple vessel 5 (4.5%) 5 (4.2%) 0.91ns
cTnI means Cardiac Troponin-I, ns means not-significant, s means significant, CAD means coronary artery disease.
Group-I: Patients with first attack of NSTEMI with Troponin-I level <6.6 ng/ml. Group-II: Patients
with first attack of NSTEMI with Troponin-I level >6.6 ng/ml.
Table-2 compares the extent of CAD and the number of occluded vessels among the two groups of cardiac troponin I. At coronary angiography, among
the 111 patients with cTnl levels <6.6 ng/ml, the rates of significant single, double and triple vessel CAD were 22.5%, 36% and 30.6% respectively. While among the 119 patients with cTnI levels >6.6 ng/ml, the rates were 19.3%, 31.1% and 46.2% respectively (p= 0.35, p= 0.21 and p <0.04 respectively) which was
cTnI= cardiac troponin I, LMCA= left main coronary artery, LAD= left anterior descending artery, LCX= left circumflex artery, LPLB= left postero-lateral branch, LPDA= left posterior descending artery, RCA= right coronary artery, RPLB= right postero-lateral branch, RPDA= right posterior descending artery, RI= ramus intermedius artery.
Group-I: Patients with first attack of NSTEMI with Troponin-I level <6.6 ng/ml. Group-II: Patients with first attack of NSTEMI with Troponin-I level >6.6 ng/ml.
Table-3 summarizes the angiographic characteristics of patients in the two cutoff levels of cTnI with
Group-I: Patients with first attack of NSTEMI with Troponin-I level <6.6 ng/ml.
Group-II: Patients with first attack of NSTEMI with Troponin-I level >6.6 ng/ml.
not statistically significant (p= 0.13). Furthermore, in patients with cTnI >6.6 ng/ml, there were also a greater proportion of patients with left main coronary artery stenosis (>50% stenosis) and a greater number of totally occluded vessels.
Table- 3
respect to the site of significance (>70%) coronary stenosis. The left anterior descending artery (LAD) was the vessel most commonly involved with significant stenosis in both the groups. In patients with cTnI levels <50 folds ULN, LAD was the commonest vessel 97 (87.3%), followed by right coronary artery (RCA) 79 (71.1%) and then left circumflex artery (LCX), 46 (41.4%). While in patients with cTnI levels >50 folds ULN, LAD was the commonest vessel, 104 (87.3%), followed by RCA 82 (68.9%) and then LCX artery 74 (62.1%). In patients with cTnI levels >50 folds ULN, there was also more involvement of the diagonal branch, left posterior descending artery and left postero-lateral branches.
The above table shows majority of the study subjects of both groups had T-inversion in ECG. Then ST depression was prevalent in both groups. Here, the difference between the two groups was statistically significant (P < 0.05).
Relation between cardiac troponin I levels and the site of coronary lesion (n=230).
Site of coronary lesion cTnI <6.6 ng/ml (n=111) cTnI > 6.6 ng/ml (n=119)
LMCA 6 (5.4%) 12 (10.0%)
LAD 97 (87.3%) 104 (87.3%)
Proximal 42 (37.8%) 50 (42.0%)
Mid-distal 55 (49.5%) 54 (45.3%)
Diagonal 23 (20.7%) 37 (31.0%)
LCX 46 (41.4%) 74 (62.1%)
Proximal 24 (21.6%) 40 (33.6%)
Mid-distal 22 (19.8%) 34 (28.5%)
Obtuse Marginal 34 (30.6%) 33 (27.7%)
LPLB 6 (5.40%) 10 (8.4%)
LPDA 0 4 (3.3%)
RCA 79 (71.1%) 82 (68.9%)
Proximal 28 (25.2%) 29 (24.3%)
Mid-distal 51 (45.9%) 53 (44.5%)
RPLB 6 (5.4%) 5 (4.2%)
RPDA 8 (7.2%) 8 (6.7%)
RI 3 (2.7%) 9 (7.5%)
Table-4
ECG profile of the study population (n=230)
ECG Change Troponin-I Level (ng/ml) p-Value
<6.6 >6.6 <0.001s
Group-I (n=111) Group-II (n=119)
Normal 35 (31.5%) 38 (31.9%)
ST-depression 36 (32.4%) 39 (32.8%)
T-inversion 40 (36.1%) 42 (35.3%)
Table-5
Comparison of Troponin-I level and Left Ventricular Ejection Fraction (LVEF) between the groups (n=230)20
Extent of CAD p-value
Troponin-I (ng/ml) Group-I (n=111) Group-II (n=119) <0.00001s
>6.6 03 108
<6.6 108 11
Chi-Squire test was done. Group-I: Patients with first attack of NSTEMI with Troponin-I level <6.6 ng/ml. Group-II: Patients with first attack of NSTEMI with Troponin-I level >6.6 ng/ml.
Group-I: Patients with first attack of NSTEMI with Troponin-I level <6.6 ng/ml.
Group-II: Patients with first attack of NSTEMI with Troponin-I level >6.6 ng/ml.
Relationship between
Group-I: Patients with first attack of NSTEMI with Troponin-I level <6.6 ng/ml.
Group-II: Patients with first attack of NSTEMI with Troponin-I level >6.6 ng/ml.
The above table shows relationship pf Troponin-I and Syntax Score with Extent of CAD of the study
The above table shows majority of the study subjects of group-I had troponin-I level <6.6 ng/ml and majority of the study subjects of group-II had troponin-I level >6.6 ng/ml. Here, the difference between the two groups was statistically significant (P < 0.05).
Table-6
The above table shows syntax score profile of the study subjects. Here, the difference between the two groups was statistically significant (P < 0.05).
Table-7
and severity of CAD
population. It shows Triple vessel disease subjects had the highest Troponin-I level & Syntax Score whereas Single vessel disease population had the lowest Tro-ponin-I & Syntax Score. Here, the difference between the two groups was statistically significant (P < 0.05)
Table- 8
Multivariate regression analysis of the risk factors of the study population (n=230)
Parameter P p-value
Age 0.20 0.57ns
Sex -0.06 0.723™
BMI 0.10 0.12ns
Smoking 0.142 0.813ns
HTN -0.194 0.325ns
DM 0.233 0.435ns
F/H of CAD -0.005 0.565ns
Dyslipidaemia -0.229 0.113ns
Extent of CAD -0.182 0.001s
ECG 0.004 0.324ns
Troponin-I 0.261 0.002s
Syntax Score -0.180 0.002s
Multivariate linear regression analysis was done. s means significant. ns means not- significant.
Syntax score profile of the study population (n=230)
Syntax Score Troponin-I Level (ng/ml) p-Value
<6.6 >6.6 <0.001s
Group-I (n=111) Group-II (n=119)
<22 14.15±5.06 18.90±9.85
23-32 24.16±8.59 24.70±5.84
>33 34.70±8.59 38.50±7.95
with Troponin-I & Syntax score of the study population (n=230)
Extent of CAD Troponin-I Level (ng/ml) Syntax Score p-Value
Group-I (n=111) Group-II (n=119) Group-I (n=111) Group-II (n=119) <0.001s
Single Vessel Disease 0.30±1.32 7.30±3.56 14.15±5.06 18.90±9.85
Double Vessel Disease 4.76±17.16 12.76±19.37 24.16±8.59 24.70±5.84
Triple Vessel Disease 6.57±20.73 16.57±18.95 34.70±8.59 38.50±7.95
The multivariate regression analysis was done for the variables studied which showed regression co-efficient for Troponin-I, Extent of CAD and Syntax Score were statistically significant (p <0.05) but the other parameters revealed no statistical significance.
60
50
40
30
20
10
0,5
1 1,5
Troponin-I
2,5
Figure-2: Correlation between Troponin-I level with extent of CAD.
The above figure shows statistically significant (<0.05) positive correlation between Troponin-I level with extent of CAD of the study population. It indicates more the Troponin-I level more involvement of coronaries and vice versa.
60 50
y = 2.6191x + 17.582 R2 = 0.3355s
£ 40 о
I 30
с
Cr>
20 10
I
I
I
10
Extent of CAD
Figure-3: Correlation between syntax score with extent of CAD.
The above figure shows statistically significant (<0.05) positive correlation between syntax score with extent of CAD of the study population. It indicates more the syntax score moreinvolvement of coronaries and vice versa.
Table- 9
Sensitivity and Specificity of Troponin-I level & Syntax Score for Extent of CAD (n=230)20
Extent of CAD
Troponin-I (ng/ml)
Syntax Score
Group-I
(n=111)
Group-II (n=119)
>6.6
High (>33)
03 (b)
108 (a)
<6.6
Low (<22) & Intermediate (23-32)
108 (d)
11
(c)
Sensitivity Specificity
91%
a = true positive c = false negative b = false positive d = true negative
0
0
2
0
0
2
4
6
8
Group-I: Patients with first attack of NSTEMI with Troponin-I level <6.6 ng/ml.
Group-II: Patients with first attack of NSTEMI with Troponin-I level >6.6 ng/ml.
The above table shows the sensitivity and specificity of Troponin-I level for left ventricular systolic dysfunction were 91% and 97% respectively.
Discussion:
Our study gives an information about the association between cardiac troponin I levels (<50 folds ULN and >50 folds ULN) & different levels of syntax score (low, intermediate & high) in NSTEMI and the number of major epicardial coronary vessels that have significant luminal narrowing (>70 % stenosis). The study showed that patients with cTnl level <6.6 ng/ml, 22.5 % of the patients had single vessel with mean syntax score of 14.15±5.06, 36 % had double vessel with syntax score of 24.16±8.59 and 30.6% had triple vessel with 34.70±8.59syntax score, while among patients with cTnI levels >6.6 ng/ml, 19.3 % of the patients had single vessel& syntax score of 18.90±9.85, 31.1 % had double vessel & syntax score of24.70±5.84 and 46.2% had triple vessel & syntax score of38.50±7.95. We found a statistically significant relationship only between cTnI level >6.6 ng/ml, high syntax score (>33) and triple vessel CAD. Due to absence of local data for such an association we took the challenge for such research. Our study revealed that 2.7 % patients with cTnI <6.6 ng/ml and only 0.84% patient in the cTnI >6.6 ng/ml group had a normal coronary angiogram. In patients with NSTEMI, there are more extensive disease when troponin levels are elevated6'7. A study analyzed clinical and angiographic variables and found patients with troponin I levels (<10 folds ULN), frequently had higher Braunwald Class angina4, more severe ECG changes, higher proportion of extensive CAD. cTnI concentration > 6.6 ng/ml predicted multi-vessel coronary artery disease with a sensitivity of 100% and specificity of 92.4% respectively9. In our study, we found that Troponin-I level >6.6 ng/ml & high syntax score (>33) has got 91% patients with multi-vessel coronary artery disease. On the other hand, Troponin-I level <6.6 ng/ml has got 9% patients with multi-vessel coronary artery disease. The difference is statistically significant between two groups (p<0.05). Our study also discovered that Troponin-I level >6.6 ng/ml & high syntax score (>33) are predictive of multi-vessel coronary artery disease with a sensitivity and specificity of 91% & 97% respectively which is quite similar to other studies9'10. Overall, the results of our study suggest that elevated troponin I levels & elevated syntax score are associated with a greater severity and extent of coronary artery disease in the setting of NSTEMI. We hypothesised that levels of Troponin-I & Syntax score could be correlated with extent & severity of coronary artery disease following NSTEMI. From the above discussion we found that in patients with first attack of NSTEMI, Troponin-I & Syntax score level serve as very sensitive and specific marker for extent & severity of coronary artery disease.
Limitations
Several limitations of our study must be acknowledged:
• The complexity of the lesions was dependent on man behind the machine.
• The majority of the study population were male. Thus, these results need to be re-evaluated in other health care center by incorporating male and female in large numbers.
• The study evaluated the extent of CAD in terms of the number of severely diseased major coronary arteries with respect to the two cutoff levels of cTnI.
• Troponin-I level estimation have become more easier & more sensitive by using the newer methods. Due to infrastructural limitations our patients' blood sample was analyzed with the aid of traditional technique.
• Syntax score analysis is a computer based calculating system which depends on the severity and location of the coronary lesions which is dependent on the operator visual estimation.
Conclusion
The present study concluded that the higher the Troponin-I level & Syntax score surrogate for higher sensitivity and specificity for extent & severity of coronary artery disease.
Recommendation
Based on the findings of the study, we have been able to suggest the following measures to ensure a more scientific diagnosis, prognosis and treatment of the patients afflicted with NSTEMI.
• In perspective of our country, Troponin-I is an available test for making diagnosis and to see prognosis in acute MI patients. Troponin-I level have an impact over left ventricular ejection fraction in patients with NSTEMI. Troponin-I level provides a note warning about the outcomes of the patients after NSTEMI. A number of studies were conducted in past for acute MI patients, mostly on STEMI. Few studies were conducted regarding NSTEMI. As, extent of coronary artery disease was correlated well with troponin-I levels; So, Troponin-I can serve dual purpose - for both diagnosis and prognosis of NSTEMI Patients.
• Syntax score is a newer technique to assess the severity of coronary artery disease. As availability of smart phone & easy access to internet it can easily be calculated.
• As, extent & severity of coronary artery disease was correlated well with troponin-I & syntax score levels; So, combination of both can serve dual purpose - for both diagnosis and prognosis of NSTEMI Patients.
• The study also recommends that aggressive revascularization strategy like early PCI and closer surveillance should be offered to NSTEMI patients with high Troponin-I & Syntax score levels, as these patients are more prone to develop complications like heart failure, arrhythmia and even sudden cardiac death.
References
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