ECG Variables in LVSD Sri Lanka
Description
Cases included the elderly patients who were older than 65 years and presented with LVSD (LVEF ≤ 50%, FS ≤ 29%) as diagnosed by echocardiography (4) (5) (6) with no other cardiovascular abnormality, while the control group included the individuals aged over 65 years whose LVEF ≥ 60% and admitted for receiving treatment for medical conditions other than any concurrent major cardiovascular disorders (ACS, MI, Heart Block, Carditis, etc). Accordingly, the study participants were recruited prospectively from the medical wards using purposive sampling method, from November 2020 to October 2021. Further, LVSD severity levels were defined as mild LVSD (LVEF= 41%-50%), moderate LVSD (LVEF= 31%-40%) and severe LVSD (LVEF< 30%) (18) (19). The study participants were also screened for their demographic information, medical history and concurrent risk factors for cardiovascular diseases, followed by 12 leads ECG recording.
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Cases included the elderly patients who were older than 65 years and presented with LVSD (LVEF ≤ 50%, FS ≤ 29%) as diagnosed by echocardiography (4) (5) (6) with no other cardiovascular abnormality, while the control group included the individuals aged over 65 years whose LVEF ≥ 60% and admitted for receiving treatment for medical conditions other than any concurrent major cardiovascular disorders (ACS, MI, Heart Block, Carditis, etc). Accordingly, the study participants were recruited prospectively from the medical wards using purposive sampling method, from November 2020 to October 2021. Further, LVSD severity levels were defined as mild LVSD (LVEF= 41%-50%), moderate LVSD (LVEF= 31%-40%) and severe LVSD (LVEF< 30%) (18) (19). The study participants were also screened for their demographic information, medical history and concurrent risk factors for cardiovascular diseases, followed by 12 leads ECG recording. A standard 12 lead ECG was recorded using Beneheart R3 ECG recorder while each study participant was resting in the supine position. The recorder was set to the recording speed of 25mm/s and a gain of 10mm/mV. The 95% Confidence Interval (CI) and p=0.05 were used as the significance level to describe the results of the statistical analysis. Both nominal/categorical variables (eg: presence/absence of LVH, ST-T wave abnormality, AF, LBBB, RBBB, pathological Q waves) and continuous numeric variables (QRS duration, cQT interval, Goldberger’s first criterion) were included in the data obtained from the study participants. Frequencies, percentages, Odds Ratios (OR), Pearson’s chi-squared test, sensitivity, specificity and p-values were used to describe the case and control-wise prevalence, predictive powers and associations of nominal ECG variables with LVSD. Independent sample t-test was used to compare means (± SD) of continuous ECG variables between case and control groups while one-way ANOVA was used to compare means of such continuous ECG variables in between each LVSD severity category. The correlations of continuous ECG measurements with LVEF, FS and LV mass were determined by Pearson’s correlation coefficient(r). The significance of the correlations has been described by referring to significance levels of 0.01 and 0.05 while the strength of each correlation was determined by referring the Guildford’s rule of thumb. Binary logistic regression was used to determine the ECG characteristics which can be the independent predictors of LVSD and their odds ratios. In addition, ROC curves and area under ROC curves (AUROC) were used to emphasize the effectiveness of ECG variables that serve as independent predictors to discriminate LVSD (LVEF <50%) from non-LVSD individuals.