Background Most electrocardiogram (ECG) studies still take advantage of traditional statistical functions, and the results are mostly presented in tables, histograms, and curves. Few papers display ECG data by visual means. The aim of this study was to analyze and show data for electrocardiographic left ventricular hypertrophy (LVH) with ST-segment elevation (STE) by a heat map in order to explore the feasibility and clinical value of heat mapping for ECG data visualization. Methods We sequentially collected the electrocardiograms of inpatients in the First Affiliated Hospital of Shantou University Medical College from July 2015 to December 2015 in order to screen cases of LVH with STE. HemI 1.0 software was used to draw heat maps to display the STE of each lead of each collected ECG. Cluster analysis was carried out based on the heat map and the results were drawn as tree maps (pedigree maps) in the heat map. Results In total, 60 cases of electrocardiographic LVH with STE were screened and analyzed. STE leads were mainly in the V1, V2 and V3 leads. The ST-segment shifts of each lead of each collected ECG could be conveniently visualized in the heat map. According to cluster analysis in the heat map, STE leads were clustered into two categories, comprising of the right precordial leads (V1, V2, V3) and others (V4, V5, V6, I, II, III, aVF, aVL, aVR). Moreover, the STE amplitude in 40% (24 out of 60) of cases reached the threshold specified in the STEMI guideline. These cases also could be fully displayed and visualized in the heat map. Cluster analysis in the heat map showed that the III, aVF and aVR leads could be clustered together, the V1, V2, V3 and V4 leads could be clustered together, and the V5, V6, I and aVL leads could be clustered together. Conclusion Heat maps and cluster analysis can be used to fully display every lead of each electrocardiogram and provide relatively comprehensive information.

Background ST-segment elevation (STE) is not a specific change for ST-segment elevation myocardial infarction (STEMI). This may lead to a mistaken diagnosis of STEMI and false-positive cardiac catheterization laboratory activation. We aimed to investigate risk factors for STE secondary to electrocardiographic LVH in order to provide more information for differential diagnosis.Methods A total of 1,590 inpatients with electrocardiographic LVH without confounding factors (such as myocardial infarction) were enrolled in this study. Data on potential risk factors and patient characteristics were collected. Logistic regression analysis and receiver operating characteristic curve (ROC) were used to identify the risk of STE in patients with LVH.Results After reviewing the ECGs, 1590 cases of electrocardiographic LVH were divided into an ST-segment elevation group (STE group, 81 cases) and non-ST segment elevation group (1509 cases). Eighty-seven cases were randomly selected from the non-ST segment elevation group to form a new non-ST segment elevation group (non-STE group, 87 cases) for further analysis. The mean age of the 168 participants (119 men, 70.83%) was 62.33 ± 16.27. Multivariate analysis showed that stroke, infection, and the value of SV1+RV5 were significantly associated with STE secondary to LVH. The area under the receiver operating characteristic curve showed that the optimal value of SV1+RV5 cut-off for predicting STE was 4.805 (sensitivity: 40.74%; specificity: 80.46%; AUC: 0.634; 95% CI: 0.550–0.719; P < 0.05).Conclusions A value of SV1+RV5 larger than 4.8 mV, stroke, and infection are independent risk factors for STE in patients with electrocardiographic LVH.