FIGURE 3.

Heatmap of 17 intravascular optical coherence tomography (IVOCT) plaque features with hierarchical clustering. R² values are plotted against each other and ordered to show the statistically different clusters (red boxes). The color key indicates the value of explained variances: R² values<0.5 are black, whereas greater values are shown in green or red with increasing intensity. Six clusters (red boxes) identified by hierarchical clustering and the IVOCT plaque features with the smallest p-values are shown on the left. Using a Spearman correlation coefficient threshold of 0.9, a total of 8 features were excluded from further analysis.