# Clustering of Heart Failure Phenotypes in Johannesburg Using Unsupervised Machine Learning
## 3 Results
### Cluster Analysis
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Clinical Parameters** & \begin{tabular}{c} **All** \\ **Patients** \\ **(_n_ = 636)** \\ \end{tabular} & \begin{tabular}{c} **Cluster 1** \\ **Uraemic** \\ **(_n_ = 229)** \\ \end{tabular} & \
\begin{tabular}{c} **Cluster 2** \\ **Hypotensive** \\ **(_n_ = 117)** \\ \end{tabular} &
\begin{tabular}{c} **Cluster 3** \\ **Congestive** \\ **(_n_ = 290)** \\ \end{tabular} & \(p\)**-Value** \\ \hline Age (years), mean & 55.6 \(\pm\) 16.9 & 56.2 \(\pm\) 17.2 & 54.3 \(\pm\) 15.9 & 55.6 \(\pm\) 16.9 & 0.7642 \\ Male sex, n (\%) & 352 (55.3) & 128 (36.4) & 66 (18.8) & 158 (44.9) & 0.9189 \\ Ethnicity, n (\%) & & & & \\ African & 380 (59.7) & 132 (34.7) & 68 (17.9) & 180 (47.4) & 0.5485 \\ Caucasian & 154 (24.2) & 57 (37.0) & 25 (16.2) & 72 (46.8) & 0.7286 \\ Indian & 72 (11.3) & 28 (38.9) & 17 (23.6) & 27 (37.5) & 0.2787 \\ Mixed Ancestry & 29 (4.6) & 12 (41.4) & 7 (24.1) & 10 (34.5) & 0.4468 \\ Clinical examination & & & & \\ Lung repetitions & 392 (61.6) & 122 (31.1) & 67 (17.1) & 203 (51.8) & 0.0002 \\ Ascites & 144 (22.6) & 23 (16.0) & 28 (19.4) & 93 (64.6) & \textless{}0.0001 \\ Cyanosed & 51 (8.0) & 9 (17.6) & 10 (19.6) & 32 (62.7) & 0.0122 \\ Hepatomegaly & 249 (39.2) & 65 (26.1) & 44 (17.7) & 140 (56.2) & \textless{}0.0001 \\ Peripheral oedema & 436 (68.6) & 115 (26.4) & 82 (18.8) & 239 (54.8) & \textless{}0.0001 \\ S3 & 324 (50.9) & 102 (31.5) & 66 (20.4) & 156 (48.1) & 0.0474 \\ JVP elevated & 493 (77.5) & 148 (30.0) & 94 (19.1) & 251 (50.9) & \textless{}0.001 \\ Systolic BP, mmHg & 128 \(\pm\) 30.1 & 135 \(\pm\) 28.6 & 117 \(\pm\) 26.5 & 128 \(\pm\) 26.2 & 0.0135 \\ Diastolic BP, mmHg & 82 \(\pm\) 19.7 & 83 \(\pm\) 17.3 & 76 \(\pm\) 16.8 & 84 \(\pm\) 18.8 & 0.7012 \\ Laboratory tests & & & & \\ Haemoglobin, g/dL & 12.9 \(\pm\) 2.5 & 12.7 \(\pm\) 2.4 & 13.2 \(\pm\) 2.3 & 13.1 \(\pm\) 2.4 & 0.0986 \\ Sodium, mmol/L & 139 \(\pm\) 5.4 & 139 \(\pm\) 4.7 & 138 \(\pm\) 4.9 & 140 \(\pm\) 5.8 & 0.4697 \\ Potassium, mmol/L & 4.4 \(\pm\) 0.7 & 4.3 \(\pm\) 0.6 & 4.5 \(\pm\) 0.8 & 4.4 \(\pm\) 0.8 & 0.1063 \\ Urea, mmol/L, IQR & 8.5 (6.0–12.5) & 14.5 \(\pm\) 31.3 & 14.3 \(\pm\) 16.0 & 11.2 \(\pm\) 16.4 & 0.0917 \\ Echocardiography & & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Baseline demographic and clinical characteristics of the study patients stratified according to clusters. Cluster 2 (hypotensive) comprised 117 (18.4%) patients with a mean age of 54.3 \(\pm\) 15.9 years. Patients in cluster 2 had a lower mean systolic and diastolic blood pressure of 117 \(\pm\) 26.5 (\(p\) = 0.0135) and 76 \(\pm\) 16.8 mmHg, respectively. The minimum systolic and diastolic blood pressure were 91 and 60 mmHg, respectively. In cluster 3 (congestive cluster), there was a predominance of patients with symptoms of fluid overload, and 93 (64.6%) patients had ascites. A total of 216 (52.8%) of patients with HFrEF were in cluster 3. The post hoc analyses for all statistically significant values are depicted in Tables 4 and 5. The SHAP values were used to estimate the contribution of each feature in the clustering of heart failure patients. Both low and high values of systolic blood pressure, age, the LVEF, and diastolic blood pressure were the top four features that played a role in discriminating between the three clusters (Figure 3). The mean SHAP value of the systolic blood pressure (SHAP value = 0.36) was approximately 2.6 times higher than that of the LVEF (SHAP value = 0.14).