Incidence of Pulmonary Hypertension in Patients with Chronic Myeloproliferative Disorders.

Background: Increased incidence of cardiac involvement and pulmonary hypertension (PH) has been reported in patients with chronic myeloproliferative disorders (CMPD). Most studies are small and retrospective except one where majority of the patient had essential thrombocytosis (ET).

Method: We conducted a study to assess the incidence of PH in patients with CMPD. Patients were excluded if they had secondary cause of PH. Diagnosis of PH was established if right ventricular systolic pressure (RVSP) by transthoracic echocardiography (TTE) and Doppler study was ≥ 35 mmHg. 27 patients with diagnosis of CMPD established by standard criterion were included in the study. 9 patients had ET, 14 had polycythemia vera (PV) and 3 had chronic myeloid leukemia (CML).

Results: Diagnosis of PH was established in 14/27 patients. 2 patients were excluded form analysis because of poor ejection fraction on TTE, 1 with PV and 1 with CML, giving final diagnosis of PH in 12/25 (48%) patients. 9 patients were males and 16 were females. Mean age at diagnosis in the entire cohort was 56.2 years and that with and without PH was 54.5 vs. 57.7 years respectively. Mean duration of follow up was 8.7 years and that with and without PH was 7.8 vs. 9.9 years respectively. 7/9 ET, 5/14 PV AND 0/2 CML patients had PH, mostly of mild to moderate severity. All patients were asymptomatic at the time of their last visit within last 2 months.

The results are depicted in the table 1.

There was no relation of PH to duration of disease, platelet count and hematocrit at diagnosis or during follow up period for the entire group or specific diagnosis of ET or PV. Because of erratic and variable duration of aspirin use by individual patients, we could not determine its significance.

Discussion: The results of our study are similar to the study reported by Garypidou et al with regard to ET. However they had only 2 patients with PV and both of them had no evidence of PH. In our study 5/14 PV (36%) patients had PH, indicating PV patients also have significant risk of having PH.

Pathogenesis of PH can be reliably related to CMPD because:

1. Cases of secondary PH were excluded

2. TTE excluded cardiac causes of PH

3. Incidence of primary PH is very low (0.2cases/100,000) and usually occurs in 3^rd or 4^th decade.

Moreover autopsy studies have demonstrated the presence of atypical megakaryocytes and thrombotic material in the lung capillaries of pulmonary hypertension patients and CMPD. Increased level of thrombopoietin also has been demonstrated in pulmonary artery of patients with PH. Thus platelets are implicated in pathogenesis of PH in patients with CMPD. Since PH seems to be common in patients with CMPD, more studies are needed to study the long-term impact of PH on survival in these patients. Impact of therapy including platelet lowering agents and ASA on development and progression of PH also needs to be studied.