Conference: 2008 International PHA Conference and Scientific Sessions
Release Date: 06.20.2008
Ishizawar D., Zhang J., Simon M.A., McCurry K.R., Mathier M.A.
University of Pittsburgh, Cardiovascular Institute, Pittsburgh, PA, USA
BACKGROUND: Lung transplantation may be necessary for patients with pulmonary arterial hypertension (PAH) who fail medical therapy. While right ventricular (RV) dilation and dysfunction may improve after lung transplantation, persistent RV failure may cause post-lung transplant morbidity and mortality. Heart-lung transplant may be preferable in patients whose RV is unlikely to recover with lung transplant alone. Criteria to predict which patients would best benefit from heart-lung transplant do not currently exist. Baseline hemodynamic data by right heart catheterization may identify patients who would benefit from heart-lung transplant.
METHODS: 102 patients seen at the University of Pittsburgh Pulmonary Hypertension (PH) Clinic with idiopathic and familial PAH, as well as PAH secondary to connective tissue disease, lung disease, and thromboembolic disease were identified retrospectively from a clinical database. Patients with PAH due to congenital heart disease and end stage liver disease (portopulmonary hypertension) were excluded. Patients were grouped into those with low cardiac index, CI (<2 L/min/m2) or normal CI (≥2 L/min/m2) at baseline. The frequency of lung transplant (LTx), heart-lung transplant (HLTx), and death were compared between patients with low or high CI. Patients were also grouped according to events (LTx, HLTx, and death). Baseline data were compared amongst these groups.
RESULTS: There were 10 LTx, 8 HLTx, 42 deaths, and 42 survivors during a mean period of 46 months. The overall cohort was 66% female, 93% Caucasian with a mean age of 54 years when first evaluated in the PH clinic. The frequency of patients in the WHO diagnostic groups was 78%, 15%, 5%, and 2% respectively for groups 1, 3, 4, and 5. WHO functional class distribution was 7%, 7%, 61%, and 25% for classes I, II, III, and IV. The frequency of patients with a low CI < 2 L/min/m2 was 37%. 26% of patients with a low CI received HLTx as compared to 3% of patients with CI ≥ 2 L/min/m2, p=0.03.
At the time of event, 96% of the patients were on PAH therapy (prostanoids -76%, endothelin receptor antagonists – 37%, or sildenafil -12%). Two patients who were not on PAH therapy had PH due to pulmonary fibrosis. Amongst patients with events, the mean CI (L/min/m2) for patients receiving LTx was 2.5, HLTx was 1.6, and death was 2.3, p=0.01; and the mean pulmonary artery O2 saturation for patients receiving LTx was 65%, HLTx was 50%, and death was 62%, p=0.003. Mean pulmonary vascular resistance, PVR (Woods unit) for patients receiving LTx was 9.8, HLTx was 14.7, and death was 8, p=0.031, and mean PVR index (Woods unit•m2) for patients receiving LTx was 19.2, HLTx was 28.2, and death was 11.6, p=0.01. Using a 4-point scale to grade RV dysfunction by echocardiogram (0=normal, 1=mild, 2=moderate, 3=severe), the mean grade for patients receiving LTx was 1.3, HLTx was 2.7, and death was 1.8, p=0.035. Of the 18 patients who received LTx or HLTx, mean survival through the follow-up period post-transplant was 35 months (31 months for the LTx group and 40 months for the HLTx group, p=0.38. There were two deaths in the LTx group at 2 weeks and 26 months post-transplant, and no deaths in the HLTx group.
DISCUSSION AND CONCLUSION: Patients receiving HLTx had lower CI compared to patients receiving LTx. This difference may reflect subjective selection criteria used at our institution to list patients for LTx or HLTx thus biasing the analytical outcome, but in consideration of the echocardiographic findings, this may also indicate that patients listed for HLTx tend to have more significant RV dysfunction at baseline. This underscores the importance of assessing baseline RV function during the initial presentation of PAH patients as it may impact upon transplant consideration. Future correlation of hemodynamic data as well as transplant outcomes between patients who successfully undergo LTx or HLTx will help better clarify the predictive value of baseline hemodynamics in determining need for HLTx.