Pulmonary arterial size and response to sildenafil in chronic thromboembolic pulmonary hypertension

J Heart Lung Transplant. 2010 Jun;29(6):610-5. doi: 10.1016/j.healun.2009.12.014. Epub 2010 Mar 15.


Background: Relative area change (RAC) of the proximal pulmonary artery is a measurement of pulmonary artery distensibility and has been shown to correlate with vasoreactivity studies in patients with idiopathic pulmonary arterial hypertension. We have previously noted a relationship between invasive hemodynamic vasoreactivity testing and long-term response to sildenafil in patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH). We therefore set out to determine whether RAC can provide useful correlatory non-invasive data.

Methods: Patients recruited to a randomized, controlled trial (RCT) of sildenafil at 40 mg 3 times daily underwent additional magnetic resonance imaging (MRI) at the baseline of the trial. Eighteen patients had an MRI that led to a diagnosis of inoperable distal CTEPH or significant residual CTEPH post-operatively. The primary end-point was improvement in 6-minute walk test (6MWT) with secondary end-points of right heart catheterization-based hemodynamics, N-terminal pro-brain natriuretic peptide (NT pro-BNP) and functional class. RAC assessed by MRI was correlated with trial end-points.

Results: Fourteen subjects with baseline MRI completed the protocol. RAC was the only baseline variable that correlated at 1 year to the primary end-point of improvement in 6MWT (r = 0.7, p = 0.006), and also to a change in NT pro-BNP (r = 0.59, p = 0.03). Using a cut-off of RAC over 20% there was an 87.5% sensitivity (95% confidence interval [CI]: 45% to 100%) and a 66.7% specificity (95% CI: 22% to 96%) for an improvement in 6MWT of >40 meters.

Conclusions: RAC correlates with functional response to sildenafil, as measured by the 6MWT, and improved heart function, as measured by NT pro-BNP. RAC shows potential in understanding and possibly predicting treatment response.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Cardiac Catheterization
  • Chronic Disease
  • Female
  • Heart / physiopathology
  • Hemodynamics
  • Humans
  • Hypertension, Pulmonary / diagnosis
  • Hypertension, Pulmonary / drug therapy*
  • Hypertension, Pulmonary / etiology*
  • Hypertension, Pulmonary / physiopathology
  • Magnetic Resonance Imaging
  • Male
  • Middle Aged
  • Natriuretic Peptide, Brain / blood
  • Peptide Fragments / blood
  • Piperazines / therapeutic use*
  • Pulmonary Artery
  • Purines / therapeutic use
  • Recovery of Function
  • Sensitivity and Specificity
  • Sildenafil Citrate
  • Single-Blind Method
  • Sulfones / therapeutic use*
  • Thromboembolism / complications*
  • Time Factors
  • Treatment Outcome
  • Vasodilator Agents / therapeutic use*
  • Walking


  • Peptide Fragments
  • Piperazines
  • Purines
  • Sulfones
  • Vasodilator Agents
  • pro-brain natriuretic peptide (1-76)
  • Natriuretic Peptide, Brain
  • Sildenafil Citrate