Table 3.
Group | SVI (Y) vs. HR (x) * | Linear Regression Line | R2 | p-Value |
---|---|---|---|---|
Group 1, ME/CFS with POTS | SVI supine | Y = −0.185x + 5028 | 0.157 | p < 0.001 |
SVI end-tilt | Y = 0.005x + 18.6 | 0.000 | p = 0.784 | |
Delta SVI | Y = 0.092x − 21.6 | 0.036 | p = 0.004 | |
Group 2, ME/CFS with normal HR-BP response | SVI supine | Y = −0.220x + 52.9 | 0.159 | p < 0.001 |
SVI end-tilt | Y = −0.154x + 35.9 | 0.192 | p < 0.001 | |
Delta SVI | Y = −0.308x −10.1 | 0.273 | p < 0.001 | |
Group 3, healthy controls | SVI supine | Y = −0.284x + 54.8 | 0.253 | p < 0.001 |
SVI end-tilt | Y = −0.232x + 45.3 | 0.390 | p < 0.001 | |
Delta SVI | Y = −0.273x − 5.6 | 0.368 | p < 0.001 |
BP: blood pressure; HR: heart rate; POTS: postural orthostatic tachycardia syndrome; SVI: stroke volume index. ME/CFS: myalgic encephalomyelitis/chronic fatigue syndrome; *: supine or end-tilt, or changes (delta: end-tilt minus supine) in parameters, where appropriate.