Background/Purpose:

The association between connective tissue disease (CTD) and pulmonary hypertension (PH) is well known, especially in the scleroderma population. However, the association between inflammatory muscle disease (IMD) and PH has not been described in detail.

Methods:

We searched our prospectively collected database of patients undergoing diagnostic right heart catheterization (RHC) from January 2000 to December 2011 for patients with a diagnosis of IMD who had been investigated at the Pulmonary Hypertension Unit, Royal Free Hospital, London (a national tertiary centre). Patient data was sourced from written notes and electronic medical records.

Results:

Of the twenty patients with IMD who underwent RHC at the unit, 17 were diagnosed with PH. Mean age was 61 years and 76% were female with 11 patients diagnosed as dermatomyositis (DM) and 6 as polymyositis (PM). Mean pulmonary artery pressure (mPAP) was 41.2 mmHg with a pulmonary vascular resistance (PVR) of 730.7 (dynes.s.cm^-5). Mean 6 minute walk test (6MWT) result was 215 meters and mean NTproBNP values were 176.5 pmol/l. On HRCT scan 70% of patients had evidence of extensive interstitial lung disease (ILD), 24% had limited fibrosis and 1 patient showed no prior evidence of ILD.

Eleven patients went on to receive vasodilator therapies. Of these, 9 underwent repeat RHC at 3-6 months. There was a trend towards improvement: mPAP fell from 40 to 34.2 mmHg (p=0.20) and PVR fell from 704 to 375 dynes.s.cm-5 (p=0.10).

In the 6MWT there was a mean increase of 65.9 meters from baseline to 3-6 months post therapy start date and this improvement was maintained with a mean final result of 380 meters. NTproBNP values showed a weak trend towards reduction, with a fall from 189 to 143 pmol/l (p=0.29) 3-6 months post treatment.

Amongst all 17 patients diagnosed with PH the overall median survival was 41.6 months. In the 12 patients with extensive ILD associated DM/PM the 1, 3 and 5 year survival rates were 75%, 42% and 28% respectively compared to 100%, 75% and 37%  for the 5 patients with limited/no ILD (p=0.19 for difference).

Conclusion:

This analysis is the largest of its kind to assess hemodynamic characteristics and functional response to treatment in this rare group of patients. Patients with IMD who develop PH have shown an improvement in mPAP, PVR, 6MWT and NTproBNP although statistical significance was not reached.

There was no significant difference between outcomes in patients with or without extensive ILD and the survival rates in patients with extensive ILD were higher when compared to a similar group of patients in a regional scleroderma population. Given the young age of some of these patients and the poor prognosis it may be beneficial to consider them for lung transplantation at an early stage in their diagnosis. Despite the poor prognosis however, this observed response to treatment may buy time for pulmonary rehabilitation and the use of combination therapies in patients who are either not eligible or waiting for transplant.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/inflammatory-muscle-disease-associated-pulmonary-hypertension-clinical-features-and-survival-at-a-national-referral-centre/