Directing therapy in pulmonary arterial hypertension using a target 6 min walk distance

The most effective approaches to escalating advanced therapies in pulmonary arterial hypertension (PAH) are controversial.

To compare outcomes before and after introducing a target 6 min walk distance (6MWD) treatment strategy in PAH using registry data.

From 2001 to 2005, WHO class II to IV patients were treated with bosentan or prostanoids. In July 2005, a target 6MWD strategy was adopted. Monotherapy continued if 6MWD remained >350 m. For patients in whom 6MWD was ≤350 m, sildenafil was added. If 6MWD remained <350 m, prostanoids were considered. Changes in 6MWD, WHO class and survival rate were compared between periods.

Before using the 6MWD strategy, there was a statistically significant improvement in mean WHO class at six, nine and 12 months (2.5±0.8 [P<0.015]; 2.5±0.8 [P<0.005]; and 2.5±0.9 [P<0.03], respectively) compared with baseline (2.9±0.9). There was a statistically significant increase in mean 6MWD at three, six, nine and 12 months (383±113 m [P<0.005]; 401±102 m [P<0.006]; 400±109 m [P<0.001]; and 399±110 m [P<0.004], respectively) compared with baseline (321±119 m). The survival rate was 95% at one and two years. From 2005 to 2009, there was a statistically significant improvement in mean WHO class at three, six, nine and 12 months (2.6±0.8 [P<0.05]; 2.3±0.9 [P<0.0001]; 2.3±0.9 [P<0.0001]; and 2.3±1.0 [P<0.0005], respectively) compared with baseline (2.8±0.7). There was statistically significant improvement in 6MWD at six months (381±126 m [P<0.05]), followed by a decline toward baseline (354±117 m). One- and two-year survival rates in the 6MWD target era were 95% and 80%, respectively.

Based on registry data, adoption of this strategy did not affect survival rates, nor cause a sustained improvement in 6MWD by 12 months. WHO class improved similarly in both treatment groups.