The purpose of this study was to determine the correlation between the simplified treadmill score (STS) and both the number of blood vessels with significant stenosis and the severity of the SYNTAX score in patients with coronary artery disease (CAD). This was an observational, cross-sectional study conducted at Dr. Soetomo General Hospital and Premier Surabaya Hospital in Indonesia from January 2011 to February 2012.
The results of the analysis using the Spearman correlation showed that there was a strong positive relationship between STS and the number of blood vessels with significant stenosis (rs=0.616 and p<0.001). Similarly, the relationship between STS and SYNTAX score obtained (rs=0.500 and p<0.001) indicates a fairly strong positive relationship.
In conclusion, there is a significant correlation between the STS as a clinical reference for estimating the probability of CAD through a weight-training test with the number of blood vessels experiencing significant stenosis.
Introduction
Coronary artery disease (CAD) is a narrowing of the coronary arteries that supply oxygen and blood to the heart.1 The treadmill test is important to evaluate cardiovascular status and functional capacity in patients with or without CAD. This test is the cheapest and most effective diagnostic tool recommended by the American Heart Association (AHA) for diagnosing CAD for the first time, with a sensitivity of 45% and a specificity of 85%.2,3
After the weight-training test, risk stratification of CAD events can be carried out, either by using the Duke treadmill score (DTS) or the simplified treadmill score (STS). In patients who have moderate- and high-risk stratification on the STS calculation, coronary angiography is performed, and also stratified with the SYNTAX score.4,5
In areas with no catheterisation laboratory facility, the ability to use the STS to predict the severity of the disease and follow-up of CAD could be very useful. We analysed patients with chest pain who underwent a weight-training test and calculated risk stratification using STS before coronary angiography diagnostics were performed.
Method
Study design
This study was an observational, cross-sectional study, to investigate the correlation between the calculated risk from the STS in the weight-training test with the number of vessels experiencing significant stenosis (stenosis >50%) and the SYNTAX score on coronary angiography performed in patients with suspected CAD. This research was conducted at Dr. Soetomo General Hospital (DSGH) and Premier Surabaya Hospital (PSH) in Indonesia from January 2011 to February 2012. Ethical approval was granted through the University of Airlangga Research Ethics Committee.
Study population and sample
The medical record data of patients with chest pain, or without chest pain but with high risk factors for CAD, with a positive training test at DSGH or PSH, who underwent coronary angiography within six months, were taken from secondary data between January 2011 to February 2012. Samples were taken by consecutive sampling.
Data analysis
All statistical tests were performed with a commercially available statistical analysis program (SPSS 23.0 for Windows). Meanwhile, to determine the distribution of abnormal data, the Saphiro-Wilk test was used. If a normal data distribution was obtained, the Pearson correlation test was used, if the data distribution was not normal, the Spearman correlation test was used.
Results
Distribution of patients by hospital
The number of patients who met the inclusion criteria in this study during the period January 2011 to February 2012 was 57, consisting of 43 (75.4%) treated at PSH and 14 (24.6%) treated at DSGH.
Characteristics of respondents
The youngest patient was 35 years old and the oldest was 73 years old, with an average (mean ± standard deviation) 54.74 ± 9.34 years. The characteristics of respondents are shown in table 1.
Table 1. Patient characteristics
| Characteristic | Category | Hospital | Total | |
| PSH | DSGH | |||
| Age, years | Mean ± SD | 56.30 ± 9.43 | 49.93 ± 7.48 | 54.74 ± 9.34 |
| Range | 35–73 | 37–58 | 35–73 | |
| Age category, n (%) | <40 years | 2 (4.7) | 2 (14.3) | 4 (7.0) |
| 41–50 years | 8 (18.6) | 5 (35.7) | 13 (22.8) | |
| 51–60 years | 20 (46.5) | 7 (50.0) | 27 (47.7) | |
| >60 years | 13 (30.2) | 0 (0) | 13 (22.8) | |
| Gender, n (%) | Male | 37 (86.0) | 6 (42.9) | 43 (75.4) |
| Female | 6 (14.0) | 8 (57.1) | 14 (24.6) | |
| Hypertension, n (%) | Yes | 28 (65.1) | 9 (64.3) | 37 (64.9) |
| No | 15 (34.9) | 5 (35.7) | 20 (35.1) | |
| Diabetes mellitus, n (%) | Yes | 14 (32.6) | 6 (42.9) | 20 (35.1) |
| No | 29 (67.4) | 8 (57.1) | 37 (64.9) | |
| Chest pain history, n (%) | Yes | 29 (67.4) | 14 (100) | 43 (75.4) |
| No | 14 (32.6) | 0 (0) | 14 (24.6) | |
| Dyslipidaemia, n (%) | Yes | 22 (51.2) | 6 (42.9) | 28 (49.1) |
| No | 21 (48.8) | 8 (57.1) | 29 (50.9) | |
| Smoking, n (%) | Yes | 13 (30.2) | 4 (28.6) | 17 (29.8) |
| No | 30 (69.8) | 10 (71.4) | 40 (70.2) | |
| Family history, n (%) | Yes | 8 (18.6) | 1 (7.1) | 9 (15.8) |
| No | 35 (81.4) | 13 (92.9) | 48 (84.2) | |
| Alcohol consumption, n (%) | Yes | 3 (7) | 0 (0) | 3 (5.3) |
| No | 40 (93) | 14 (100) | 54 (94.7) | |
| Chest pain during exercise, n (%) | Yes | 3 (7) | 7 (50) | 10 (17.5) |
| No | 40 (93) | 7 (50) | 47 (82.5) | |
| Maximum heart rate, bpm | Mean ± SD | 144.26 ± 17.46 | 132 ± 15.18 | 141.25 ± 17.62 |
| Range | 102–181 | 98–156 | 98–181 | |
| METs, kcal/kg/hour | Mean ± SD | 7.60 ± 2.64 | 5.34 ± 1.26 | 7.04 ± 2.56 |
| Range | 3.0–13.0 | 2.8–8.0 | 2.8–13.0 | |
| Key: DSGH = Dr. Soetomo General Hospital; MET = metabolic equivalent; PSH = Premier Surabaya Hospital; SD = standard deviation | ||||
Number of blood vessels with significant stenosis
Of the total 57 patients who had a positive weight-training test and had coronary angiography performed, 10 patients were found to be normal, 19 patients had single-vessel disease, 15 patients had double-vessel disease, and 13 patients had triple-vessel disease.
STS results
In patients undergoing the weight-training test, the risk stratification was calculated using the STS calculation. The value of STS in patients at PSH and DSGH was between 19 and 90 with an average of 58.74. In the distribution of CAD risk according to the STS category, there were 26 high-risk patients, 23 moderate-risk patients, and eight low-risk patients.
SYNTAX score results
Patients who underwent coronary angiography, both at DSGH and at PSH, obtained a SYNTAX score between 0 and 71.5 with an average of 15.75. The distribution of CAD risk according to the SYNTAX score category was low (<22) in 41 patients, moderate (23–32) in 10 patients and high (>32) in six patients.
Correlation between STS and number of blood vessels with significant stenosis and SYNTAX score
The results of the analysis with the Spearman correlation showed a relationship between the STS and the number of blood vessels with significant stenosis (vessel disease) and the SYNTAX score. The relationship between the number of blood vessels with significant stenosis and STS was found to be rs=0.616 and p<0.001 indicating a strong positive relationship. Similarly, the relationship between STS and SYNTAX score obtained rs=0.500 and p<0.001 indicating a fairly strong positive relationship. The relationship between variables can be seen in figures 1 and 2.
Discussion
CAD is an atherosclerotic disease that occurs chronically, slowly but progressively, and is a degenerative disease. The treadmill test is important to evaluate cardiovascular status and functional capacity in patients with or without CAD. This test is the cheapest and most effective diagnostic tool recommended by the American Heart Association (AHA) for diagnosing CAD for the first time, with a sensitivity of 45% and a specificity of 85%.2,3
We showed a strong positive relationship between STS and the number of blood vessels with significant stenosis (rs=0.616 and p<0.001). Thus, the higher the STS value, the higher the number of blood vessels likely with significant stenosis. These results are in line with a study at Jeddah National Hospital between January 2003 and March 2005, examining all patients who underwent weight-training trials.2 From a total of 212 subjects (95% male), 51 subjects (24%) were included in the high-risk group with a STS of more than 60. Only 22% of the high-risk group underwent coronary angiography, but almost all of them had CAD in two or three vessels with significant stenosis (double/triple-vessel disease).2
The study at Jeddah National Hospital, found the calculation of the score with the STS on the weight-training test is more significant than the Duke treadmill score (DTS) because it has several clinical variables including a history of diabetes mellitus, dyslipidaemia, and angina pectoris. While the electrocardiographic (ECG) criteria in the weight-training test include maximum pulse, ST-depression during exercise and exercise that triggers angina as part of the STS assessment.
In our study at DSGH and PSH, patients who underwent the weight-training test were mostly male (75.4%) and mostly in the age categories 51–60 years (47.7%) and over 60 years (22.8%). Many patients had a history of typical chest pain or angina (75.4%), hypertension (64.9%), dyslipidaemia (49.1%), diabetes mellitus (35.1%), and/or smoking (29.8%). This is in line with a number of large epidemiological studies in North America and Europe identifying risk factors for the development of atherosclerosis, including dyslipidaemia, hypertension, smoking, air pollution, diabetes mellitus, age, and gender. Men have traditionally had a high prevalence of CAD. In women, especially after menopause, the presence of diabetes and/or cigarette use, reduces the protection against heart disease. Age is a strong risk factor for CAD. Approximately 82% of people die from CAD at the age of 65 years or older.6 Several of these risk factors are criteria in the STS assessment.
We also found a strong positive relationship between STS and SYNTAX score (rs=0.500 and p<0.001). The reason for the strong positive relationship is likely because STS also takes into account a number of risk factors for CAD, such as age, diabetes mellitus, dyslipidaemia, a history of previous chest pain, in addition to ST-depression and the incidence of chest pain during the weight-training test.
Until now there has been no previous research that directly links the STS with the SYNTAX score. However, in this study there was a strong positive correlation between STS and blood vessels with significant stenosis, the higher the STS, the more blood vessels with stenosis. There is also a strong positive correlation between vessels with significant stenosis and the SYNTAX score, so that the more blood vessels with significant stenosis, the higher the SYNTAX score. There is a fairly strong positive correlation between STS and the SYNTAX score, the higher the STS, the higher the SYNTAX score, thus, reflecting a more complex coronary stenosis that results in a higher technical challenge and a worse prognosis.7 The SYNTAX score was also designed to anticipate the risk of percutaneous revascularisation by calculating the functional impact of the coronary circulation with various anatomic abnormalities, including bifurcation, total occlusion, thrombus, calcification, and small vessels.7
The limitation of the SYNTAX score is that patients with the same SYNTAX score calculation may not necessarily have the same outcome, depending on patient risk factors, such as diabetes, chronic kidney disease, emergency situations, left ventricular ejection fraction, and age. Therefore, there are several assessments that combine the SYNTAX score, including the global risk classification (GRC) and the clinical SYNTAX score (CSS). GRC is a pre-operative assessment that combines EuroSCORE and SYNTAX scores, which are divided into three risk categories: high (EuroSCORE >6 and SYNTAX score >26), moderate (EuroSCORE >6 or SYNTAX score >26), low (EuroSCORE <6 and SYNTAX score <26).5,8 However, due to time constraints, this study was only based on the SYNTAX score. This study also has a weakness, namely the incomplete load training data on secondary data so that it cannot be used for STS assessment.
However, the weight-training test has a good future as an initial examination for diagnosis and prognosis for patients with CAD. STS assessment can help identify patients for whom coronary angiography will be performed to predict the complexity of coronary artery narrowing and its prognosis.
Key messages
- Based on the results of this study, there is a significant correlation between the simplified treadmill score (STS) as a clinical reference for estimating the probability of coronary artery disease (CAD) through a weight-training test with blood vessels experiencing significant stenosis
- The higher the STS, the higher the SYNTAX score, which reflects a more complex coronary stenosis that results in a higher technical challenge and a poorer prognosis
- STS assessment can help identify patients for whom coronary angiography will be performed to predict the complexity of coronary artery narrowing and its prognosis
Conflicts of interest
None declared.
Funding
None.
Study approval
Ethical approval was granted through the University of Airlangga Research Ethics Committee.
References
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