Clinically significant change in stroke volume in pulmonary hypertension.
BACKGROUND
Stroke volume is probably the best hemodynamic parameter because it reflects therapeutic changes and contains prognostic information in pulmonary hypertension (PH). Stroke volume directly reflects right ventricular function in response to its load, without the correction of compensatory increased heart rate as is the case for cardiac output. For this reason, stroke volume, which can be measured noninvasively, is an important hemodynamic parameter to monitor during treatment. However, the extent of change in stroke volume that constitutes a clinically significant change is unknown. The aim of this study was to determine the minimal important difference (MID) in stroke volume in PH.


METHODS
One hundred eleven patients were evaluated at baseline and after 1 year of follow-up with a 6-min walk test (6MWT) and cardiac MRI. Using the anchor-based method with 6MWT as the anchor, and the distribution-based method, the MID of stroke volume change could be determined.


RESULTS
After 1 year of treatment, there was, on average, a significant increase in stroke volume and 6MWT. The change in stroke volume was related to the change in 6MWT. Using the anchor-based method, an MID of 10 mL in stroke volume was calculated. The distribution-based method resulted in an MID of 8 to 12 mL.


CONCLUSIONS
Both methods showed that a 10-mL change in stroke volume during follow-up should be considered as clinically relevant. This value can be used to interpret changes in stroke volume during clinical follow-up in PH.
van Wolferen
Serge A
SA
Department of Pulmonary Disease, VU University Medical Center, Amsterdam, The Netherlands.
van de Veerdonk
Marielle C
MC
Department of Pulmonary Disease, VU University Medical Center, Amsterdam, The Netherlands.
Mauritz
Gert-Jan
GJ
Department of Pulmonary Disease, VU University Medical Center, Amsterdam, The Netherlands.
Jacobs
Wouter
W
Department of Pulmonary Disease, VU University Medical Center, Amsterdam, The Netherlands.
Marcus
J Tim
JT
Department of Physics and Medical Technology, Institute for Cardiovascular Research ICaR-VU, VU University Medical Center, Amsterdam, The Netherlands.
Marques
Koen M J
KMJ
Department of Cardiology, VU University Medical Center, Amsterdam, The Netherlands.
Bronzwaer
Jean G F
JGF
Department of Cardiology, VU University Medical Center, Amsterdam, The Netherlands.
Heymans
Martijn W
MW
Department of Epidemiology and Biostatistics, VU University Medical Center, Amsterdam, The Netherlands.
Boonstra
Anco
A
Department of Pulmonary Disease, VU University Medical Center, Amsterdam, The Netherlands.
Postmus
Pieter E
PE
Department of Pulmonary Disease, VU University Medical Center, Amsterdam, The Netherlands.
Westerhof
Nico
N
Department of Pulmonary Disease, VU University Medical Center, Amsterdam, The Netherlands.
Vonk Noordegraaf
Anton
A
Department of Pulmonary Disease, VU University Medical Center, Amsterdam, The Netherlands. Electronic address: a.vonk@vumc.nl.
D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006976:Hypertension, Pulmonary / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D013318:Stroke Volume