Clustering regional patterns of left ventricular longitudinal strain in systemic sclerosis-related pulmonary hypertension

Background: Systemic sclerosis-related pulmonary hypertension (SSc-PH) is a heterogeneous disease, often complicated by concomitant left ventricular (LV) dysfunction. However, the contribution of heterogeneity in LV dysfunction is unclear. The objective in this study was to identify regional clusters of LV longitudinal strain via echocardiography to determine how subgroups of LV dysfunction contribute to mortality in SSc-PH. Methods: We performed a retrospective observational study on 124 patients with SSc-PH in which LV longitudinal strain was collected over a 16-segment model. We applied K-means clustering to LV longitudinal strain at each segment using the Calinski-Harabasz index. Our primary outcome was time to all-cause mortality. Results: Patients with SSc-PH were divided into two clusters (Cluster 1: N = 59; Cluster 2: N = 65). The most pronounced differences in longitudinal strain between each cluster were observed at the basal and mid segments, particularly at the interventricular septum. In comparison to Cluster 1, Cluster 2 was characterized by both regional and global reductions in LV and right ventricular (RV) free wall longitudinal strain, greater PH severity, and greater functional limitation by New York Heart Association with a hazard ratio of 2.06 (95 % CI: 1.21, 3.50) for all-cause mortality. Conclusion: Using K-means clustering of regional patterns of LV longitudinal strain, we identified a distinct phenotype of patients at increased risk for mortality. Most of the pronounced differences in longitudinal strain between each cluster were observed at the basal and mid segments, particularly at the interventricular septum.