Page 106 - Assessing right ventricular function and the pulmonary circulation in pulmonary hypertension Onno Anthonius Spruijt
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Remarkably, we observed a significant improvement in hemodynamics, right ventricular function and exercise capacity upon pulmonary hypertension specific vasodilatory therapy without an impact on oxygen saturation in this cohort as in comparison to the IPAH patients with an moderately reduced or preserved DLCO.
Less follow-up data was available in the DLCO<43% group compared to the DLCO 43-62% and DLCO>62% group which could have led to a selection bias and subsequent overestimation of the treatment effect in the DLCO<43% group. However, no survival difference existed in the DLCO<43% group between the subjects with and without available follow-up data. This to some extent suggests that the subjects in the DLCO<43% group with follow-up data are representative for the total DLCO<43% group. Furthermore, survival differences between the DLCO<43% and the moderately reduced and preserved DLCO groups continued to exist when only the subjects with follow-up data were entered in the survival analysis further arguing against the presence of an important selection bias. At follow-up, the DLCO<43% group received more combination therapy compared to the DLCO≥43% groups. This may have confounded our results.
Based on the pulmonary vascular response on treatment there is no reason to withhold pulmonary arterial hypertension specific treatment from patients with IPAH and a severely reduced DLCO. The similarities in hemodynamic and cardiac treatment responses between IPAH patients with a severely reduced DLCO and IPAH patients with a preserved DLCO suggests that the poor survival in the low DLCO group is not explained by unresponsiveness of the pulmonary vasculature to current pulmonary arterial hypertension specific medications. Survival differences may be partially explained by the fact that the DLCO<42% group was older [16]. Cox proportional hazard analyses showed that age was a confounder for the differences in survival between groups, however, survival differences remained after adjusting for age. As such, the question remains why survival in this subgroup of patients with IPAH and a severely reduced DLCO is so poor [6].
Conclusions
Patients with IPAH and a severely reduced DLCO show a similar response to PH specific vasodilatory therapy as patients with IPAH and a moderately or preserved DLCO in terms of hemodynamics, right ventricular function, exercise capacity and oxygenation.





























































































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