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Linear and nonlinear analysis of normal and CAD-affected heart rate signals

Acharya UR, Faust O, Sree V, Swapna G, Martis RJ, Kadri NA, et al.

Comput Methods Programs Biomed, 2014;113(1):55-68.
PMID: 24119391 DOI: 10.1016/j.cmpb.2013.08.017

Coronary artery disease (CAD) is one of the dangerous cardiac disease, often may lead to sudden cardiac death. It is difficult to diagnose CAD by manual inspection of electrocardiogram (ECG) signals. To automate this detection task, in this study, we extracted the heart rate (HR) from the ECG signals and used them as base signal for further analysis. We then analyzed the HR signals of both normal and CAD subjects using (i) time domain, (ii) frequency domain and (iii) nonlinear techniques. The following are the nonlinear methods that were used in this work: Poincare plots, Recurrence Quantification Analysis (RQA) parameters, Shannon entropy, Approximate Entropy (ApEn), Sample Entropy (SampEn), Higher Order Spectra (HOS) methods, Detrended Fluctuation Analysis (DFA), Empirical Mode Decomposition (EMD), Cumulants, and Correlation Dimension. As a result of the analysis, we present unique recurrence, Poincare and HOS plots for normal and CAD subjects. We have also observed significant variations in the range of these features with respect to normal and CAD classes, and have presented the same in this paper. We found that the RQA parameters were higher for CAD subjects indicating more rhythm. Since the activity of CAD subjects is less, similar signal patterns repeat more frequently compared to the normal subjects. The entropy based parameters, ApEn and SampEn, are lower for CAD subjects indicating lower entropy (less activity due to impairment) for CAD. Almost all HOS parameters showed higher values for the CAD group, indicating the presence of higher frequency content in the CAD signals. Thus, our study provides a deep insight into how such nonlinear features could be exploited to effectively and reliably detect the presence of CAD.

Matched MeSH terms: Coronary Artery Disease/physiopathology*
The role of fractional flow reserve in pre-operative coronary angiography in redefining functional syntax score and cardiac risk in multivessel coronary artery disease

Yew KL

Int J Cardiol, 2014 Dec 20;177(3):e163-4.
PMID: 25217213 DOI: 10.1016/j.ijcard.2014.08.142
Matched MeSH terms: Coronary Artery Disease/physiopathology
Application of stacked convolutional and long short-term memory network for accurate identification of CAD ECG signals

Tan JH, Hagiwara Y, Pang W, Lim I, Oh SL, Adam M, et al.

Comput Biol Med, 2018 03 01;94:19-26.
PMID: 29358103 DOI: 10.1016/j.compbiomed.2017.12.023

Coronary artery disease (CAD) is the most common cause of heart disease globally. This is because there is no symptom exhibited in its initial phase until the disease progresses to an advanced stage. The electrocardiogram (ECG) is a widely accessible diagnostic tool to diagnose CAD that captures abnormal activity of the heart. However, it lacks diagnostic sensitivity. One reason is that, it is very challenging to visually interpret the ECG signal due to its very low amplitude. Hence, identification of abnormal ECG morphology by clinicians may be prone to error. Thus, it is essential to develop a software which can provide an automated and objective interpretation of the ECG signal. This paper proposes the implementation of long short-term memory (LSTM) network with convolutional neural network (CNN) to automatically diagnose CAD ECG signals accurately. Our proposed deep learning model is able to detect CAD ECG signals with a diagnostic accuracy of 99.85% with blindfold strategy. The developed prototype model is ready to be tested with an appropriate huge database before the clinical usage.

Matched MeSH terms: Coronary Artery Disease/physiopathology*
Evaluation of functional severity of coronary artery disease and fluid dynamics' influence on hemodynamic parameters: A review

Govindaraju K, Badruddin IA, Viswanathan GN, Ramesh SV, Badarudin A

Phys Med, 2013 May;29(3):225-32.
PMID: 22704601 DOI: 10.1016/j.ejmp.2012.03.008

Coronary Artery Disease (CAD) is responsible for most of the deaths in patients with cardiovascular diseases. Diagnostic coronary angiography analysis offers an anatomical knowledge of the severity of the stenosis. The functional or physiological significance is more valuable than the anatomical significance of CAD. Clinicians assess the functional severity of the stenosis by resorting to an invasive measurement of the pressure drop and flow. Hemodynamic parameters, such as pressure wire assessment fractional flow reserve (FFR) or Doppler wire assessment coronary flow reserve (CFR) are well-proven techniques to evaluate the physiological significance of the coronary artery stenosis in the cardiac catheterization laboratory. Between the two techniques mentioned above, the FFR is seen as a very useful index. The presence of guide wire reduces the coronary flow which causes the underestimation of pressure drop across the stenosis which leads to dilemma for the clinicians in the assessment of moderate stenosis. In such condition, the fundamental fluid mechanics is useful in the development of new functional severity parameters such as pressure drop coefficient and lesion flow coefficient. Since the flow takes place in a narrowed artery, the blood behaves as a non-Newtonian fluid. Computational fluid dynamics (CFD) allows a complete coronary flow simulation to study the relationship between the pressure and flow. This paper aims at explaining (i) diagnostic modalities for the evaluation of the CAD and valuable insights regarding FFR in the evaluation of the functional severity of the CAD (ii) the role of fluid dynamics in measuring the severity of CAD.

Matched MeSH terms: Coronary Artery Disease/physiopathology*
Coronary CT angiography with single-source and dual-source CT: comparison of image quality and radiation dose between prospective ECG-triggered and retrospective ECG-gated protocols

Sabarudin A, Sun Z, Yusof AK

Int J Cardiol, 2013 Sep 30;168(2):746-53.
PMID: 23098849 DOI: 10.1016/j.ijcard.2012.09.217

This study is conducted to investigate and compare image quality and radiation dose between prospective ECG-triggered and retrospective ECG-gated coronary CT angiography (CCTA) with the use of single-source CT (SSCT) and dual-source CT (DSCT).

Matched MeSH terms: Coronary Artery Disease/physiopathology
Sleep duration, sleep quality, and markers of subclinical arterial disease in healthy men and women

Kim CW, Chang Y, Zhao D, Cainzos-Achirica M, Ryu S, Jung HS, et al.

Arterioscler Thromb Vasc Biol, 2015 Oct;35(10):2238-45.
PMID: 26359509 DOI: 10.1161/ATVBAHA.115.306110

OBJECTIVE: Short and long sleep duration are associated with increased risk of clinical cardiovascular events, but the association between sleep duration and subclinical cardiovascular disease is not well established. We examined the association between sleep duration and sleep quality with coronary artery calcification (CAC) and with brachial-ankle pulse wave velocity (PWV) in a large sample of young and middle-aged asymptomatic adults.
APPROACH AND RESULTS: We conducted a cross-sectional study of adult men and women who underwent a health checkup examination, including assessment of sleep duration and quality and coupled with either CAC (n=29 203) or brachial-ankle PWV (n=18 106). The multivariate-adjusted CAC score ratios (95% confidence interval) comparing sleep durations of ≤5, 6, 8, and ≥9 hours with 7 hours of sleep were 1.50 (1.17-1.93), 1.34 (1.10-1.63), 1.37 (0.99-1.89), and 1.72 (0.90-3.28), respectively (P for quadratic trend=0.002). The corresponding average differences in brachial-ankle PWV were 6.7 (0.75-12.6), 2.9 (-1.7 to 7.4), 10.5 (4.5-16.5), and 9.6 (-0.7 to 19.8) cm/s, respectively (P for quadratic trend=0.019). Poor subjective sleep quality was associated with CAC in women but not in men, whereas the association between poor subjective sleep quality and brachial-ankle PWV was stronger in men than in women.
CONCLUSIONS: In this large study of apparently healthy men and women, extreme sleep duration and poor subjective sleep quality were associated with increased prevalence of CAC and higher PWV. Our results underscore the importance of an adequate quantity and quality of sleep to maintain cardiovascular health.
KEYWORDS: coronary calcification; pulse wave velocity; sleep duration; sleep quality; subclinical atherosclerosis

Matched MeSH terms: Coronary Artery Disease/physiopathology*
Renal outcome following on- and off-pump coronary artery bypass graft surgery

Ooi JS, Abdul Rahman MR, Shah SA, Dimon MZ

Asian Cardiovasc Thorac Ann, 2008 Dec;16(6):468-72.
PMID: 18984756

A prospective study was carried out to compare the outcomes of patients with preexisting non-dialysis-dependent renal dysfunction who underwent coronary artery bypass grafting with or without cardiopulmonary bypass. Elective off-pump coronary artery bypass was performed in 29 patients with renal dysfunction. Their results were compared with those of a similar group of 35 patients who underwent the conventional on-pump coronary artery grafting. There was a significant deterioration in creatinine clearance in the on-pump group on days 1, 2, and 4 after surgery, while creatinine clearance in the off-pump group remained close to the baseline level. Both groups had improved to the preoperative creatinine clearance values on follow-up at 4 weeks. It was concluded that off-pump surgery provided better renal protection than the conventional on-pump technique in patients with preexisting non-dialysis-dependent renal dysfunction.

Matched MeSH terms: Coronary Artery Disease/physiopathology
Fulltext Fifteen new risk loci for coronary artery disease highlight arterial-wall-specific mechanisms

Howson JMM, Zhao W, Barnes DR, Ho WK, Young R, Paul DS, et al.

Nat Genet, 2017 Jul;49(7):1113-1119.
PMID: 28530674 DOI: 10.1038/ng.3874

Coronary artery disease (CAD) is a leading cause of morbidity and mortality worldwide. Although 58 genomic regions have been associated with CAD thus far, most of the heritability is unexplained, indicating that additional susceptibility loci await identification. An efficient discovery strategy may be larger-scale evaluation of promising associations suggested by genome-wide association studies (GWAS). Hence, we genotyped 56,309 participants using a targeted gene array derived from earlier GWAS results and performed meta-analysis of results with 194,427 participants previously genotyped, totaling 88,192 CAD cases and 162,544 controls. We identified 25 new SNP-CAD associations (P < 5 × 10-8, in fixed-effects meta-analysis) from 15 genomic regions, including SNPs in or near genes involved in cellular adhesion, leukocyte migration and atherosclerosis (PECAM1, rs1867624), coagulation and inflammation (PROCR, rs867186 (p.Ser219Gly)) and vascular smooth muscle cell differentiation (LMOD1, rs2820315). Correlation of these regions with cell-type-specific gene expression and plasma protein levels sheds light on potential disease mechanisms.

Matched MeSH terms: Coronary Artery Disease/physiopathology
Fulltext Young coronary artery disease in patients undergoing percutaneous coronary intervention

Zuhdi AS, Mariapun J, Mohd Hairi NN, Wan Ahmad WA, Abidin IZ, Undok AW, et al.

Ann Saudi Med, 2014 1 15;33(6):572-8.
PMID: 24413861 DOI: 10.5144/0256-4947.2013.572

BACKGROUND AND OBJECTIVES: Understanding the nature and pattern of young coronary artery disease (CAD) is important due to the tremendous impact on these patients' socio-economic and physical aspect. Data on young CAD in the southeast Asian region is rather patchy and limited. Hence we utilized our National Cardiovascular Disease Database (NCVD)-Percutaneous Coronary Intervention (PCI) Registry to analyze young patients who underwent PCI in the year 2007 to 2009.
DESIGN AND SETTINGS: This is a retrospective study of all patients who had undergone coronary angioplasty from 2007 to 2009 in 11 hospitals across Malaysia.
METHODS: Data were obtained from the NCVD-PCI Registry, 2007 to 2009. Patients were categorized into 2 groups-young and old, where young was defined as less than 45 years for men and less than 55 years for women and old was defined as more than or equals to 45 years for men and more than or equals to 55 years for women. Patients' baseline characteristics, risk factor profile, extent of coronary disease and outcome on dis.charge, and 30-day and 1-year follow-up were compared between the 2 groups.
RESULTS: We analyzed 10268 patients, and the prevalence of young CAD was 16% (1595 patients). There was a significantly low prevalence of Chinese patients compared to other major ethnic groups. Active smoking (30.2% vs 17.7%) and obesity (20.9% vs 17.3%) were the 2 risk factors more associated with young CAD. There is a preponderance toward single vessel disease in the young CAD group, and they had a favorable clinical outcome in terms of all-cause mortality at discharge (RR 0.49 [CI 0.26-0.94]) and 1-year follow-up (RR 0.47 [CI 0.19-1.15]).
CONCLUSION: We observed distinctive features of young CAD that would serve as a framework in the primary and secondary prevention of the early onset CAD.

Matched MeSH terms: Coronary Artery Disease/physiopathology
Brachial-ankle pulse wave velocity is associated with coronary calcium in young and middle-aged asymptomatic adults: The Kangbuk Samsung Health Study

Cainzos-Achirica M, Rampal S, Chang Y, Ryu S, Zhang Y, Zhao D, et al.

Atherosclerosis, 2015 Aug;241(2):350-6.
PMID: 26071657 DOI: 10.1016/j.atherosclerosis.2015.05.031

OBJECTIVE: To evaluate the association between brachial-ankle pulse wave velocity (baPWV), a convenient, non-radiating, readily available measurement of arterial stiffness, and coronary artery calcium (CAC), a reliable marker of coronary atherosclerosis, in a large sample of young and middle-aged asymptomatic adults; and to assess the incremental value of baPWV for detecting prevalent CAC beyond traditional risk factors.
METHODS: Cross-sectional study of 15,185 asymptomatic Korean adults who voluntarily underwent a comprehensive health screening program including measurement of baPWV and CAC. BaPWV was measured using an oscillometric method with cuffs placed on both arms and ankles. CAC burden was assessed using a multi-detector CT scan and scored following Agatston's method.
RESULTS: The prevalence of CAC > 0 and CAC > 100 increased across baPWV quintiles. The multivariable-adjusted odds ratios (95% CI) for CAC > 0 comparing baPWV quintiles 2-5 versus quintile 1 were 1.06 (0.87-1.30), 1.24 (1.02-1.50), 1.39 (1.15-1.69) and 1.60 (1.31-1.96), respectively (P trend < 0.001). Similarly, the relative prevalence ratios for CAC > 100 were 1.30 (0.74-2.26), 1.59 (0.93-2.71), 1.74 (1.03-2.94) and 2.59 (1.54-4.36), respectively (P trend < 0.001). For CAC > 100, the area under the ROC curve for baPWV alone was 0.71 (0.68-0.74), and the addition of baPWV to traditional risk factors significantly improved the discrimination and calibration of models for detecting prevalent CAC > 0 and CAC > 100.
CONCLUSIONS: BaPWV was independently associated with the presence and severity of CAC in a large sample of young and middle-aged asymptomatic adults. BaPWV may be a valuable tool for identifying apparently low-risk individuals with increased burden of coronary atherosclerosis.
KEYWORDS: Arterial stiffness; Atherosclerosis; Coronary artery calcium; Pulse wave velocity; Subclinical disease

Matched MeSH terms: Coronary Artery Disease/physiopathology