ST segment/heart rate hysteresis improves the diagnostic accuracy of ECG stress test for coronary artery disease in patients with left ventricular hypertrophy

Methodological identification of anomalies episodes in ECG streams: a systematic mapping study

An electrocardiogram is a medical examination tool for measuring different patterns of heart blood flow circle either in the form of usual or non-invasive patterns. These patterns are useful for the identification of morbidity condition of the heart especially in certain conditions of heart abnormality and arrhythmia. Myocardial infarction (MI) is one of them that happened due to sudden blockage of blood by the cause of malfunction of heart. In electrocardiography (ECG) intensity of MI is highlighted on the basis of unusual patterns of T wave changes. Various studies have contributed for MI through T wave's classification, but more to the point of T wave has always attracted the ECG researchers. Methodology. This Study is primarily designed for proposing the combination of latest methods that are worked for the solutions of pre-defined research questions. Such solutions are designed in the form of the systematic review process (SLR) by following the Kitchen ham guidance. The literature survey is a two phase's process, at first phase collect the articles that were published in IEEE Xplore, Scopus, science direct and Springer from 2008 to 2023. It consist of steps; the first level is executed by filtrating the articles on the basis of keyword phase of title and abstract filter. Similarly, at two level the manuscripts are scanned through filter of eligibility criteria of articles selection. The last level belongs to the quality assessment of articles, in such level articles are rectified through evaluation of domain experts. Results. Finally, the selected articles are addressed with research questions and briefly discuss these selected state-of-the-art methods that are worked for the T wave classification. These address units behave as solutions to research problems that are highlighted in the form of research questions. Conclusion and future directions. During the survey process for these solutions, we got some critical observations in the form of gaps that reflected the other directions for researchers. In which feature engineering, different dependencies of ECG features and dimensional reduction of ECG for the better ECG analysis are reflection of future directions.

Factors for heterogeneous outcomes of angina and myocardial ischemia without obstructive coronary atherosclerosis

BACKGROUND AND OBJECTIVES

The absence of obstructive coronary artery disease (CAD) in patients with angina is common, but its prognosis is debated. We investigated outcomes of such patients to identify predictors of cardiovascular events.

METHODS

We selected 1014 patients with angina, evidence of myocardial ischemia at the electrocardiogram (ECG) exercise test or imaging stress tests, and nonobstructive CAD (absence of lumen diameter reduction ≥50%) at coronary angiography between 1999 and 2015. Note that, 1905 age- and risk factors-matched asymptomatic subjects served as "real-world" comparators. The primary endpoint was the occurrence of all-cause death or myocardial infarction.

RESULTS

At 6-years median follow-up (interquartile range, 3-9 years), the primary endpoint occurred in 53 patients (5.5%, 0.92/100 person-years). Besides similar event rates compared with asymptomatic subjects (hazard ratio [HR] 0.85, 95% confidence interval [CI] 0.62-1.15, p = 0.28), the index population showed a very heterogeneous prognosis. Patients with nonobstructive CAD (HR 1.85, 95% CI 1.02-3.37, p = 0.04, compared with "normal" coronary arteries) and ischemia at imaging tests (HR 2.11, 95% CI 1.07-4.14, p = 0.03, compared with ischemia detected only at the ECG exercise test) were at higher risk and those with both these components showing even >10-fold event rates as compared with the absence of both. Three-hundred and twenty-five patients (34%) continued to experience angina, 69 (7.2%) underwent repeat coronary angiography, and 14 (1.5%) had consequent coronary revascularization for atherosclerosis progression.

CONCLUSION

Apart from the impaired quality of life, angina without obstructive CAD has an overall benign but very heterogeneous prognosis. Nonobstructive CAD and myocardial ischemia at imaging tests both confer a higher risk.

Cadmium stress assessment based on the electrocardiogram characteristics of zebra fish (Danio rerio): QRS complex could play an important role

The electrocardiogram (ECG) of zebra fish (Danio rerio) expresses cardiac features that are similar to humans. Here we use sharp microelectrode measurements to obtain ECG characteristics in adult zebra fish and analyze the effects of cadmium chloride (CdCl₂) on the heart. We observe the overall changes of ECG parameters in different treatments (0.1 TU, 0.5 TU and 1.0 TU CdCl₂), including P wave, Q wave, R wave, S wave, T wave, PR interval (atrial contraction), QRS complex (ventricular depolarization), ST segment, and QT interval (ventricular repolarization). The trends of the ECG parameters showed some responses to the concentration and exposure time of CdCl₂, but it was difficult to obtain more information about the useful indicators in water quality assessment depending on tendency analysis alone. A self-organizing map (SOM) showed that P values, R values, and T values were similar; R wave and T wave amplitude were similar; and most important, QRS value was similar to the CdCl₂ stress according to the classified data patterns including CdCl₂ stress (E) and ECG components based on the Ward linkage. It suggested that the duration of QRS complex was related to environmental stress E directly. The specification and evaluation of ECG parameters in Cd²⁺ pollution suggested that there is a markedly significant correlation between QRS complex and CdCl₂ stress with the highest r (0.729) and the smallest p (0.002) among all ECG characteristics. In this case, it is concluded that QRS complex can be used as an indicator in the CdCl₂ stress assessment due to the lowest AIC data abased on the linear regression model between the CdCl₂ stress and ECG parameters.