From the Guidelines
Pulmonary artery pressure improvement can be seen as early as a few hours to days after starting calcium channel blockers (CCBs) in patients with vasoreactive pulmonary arterial hypertension (PAH) who demonstrate a positive acute vasoreactivity test. The treatment typically begins with long-acting nifedipine at 30-60 mg daily or amlodipine at 2.5-10 mg daily, with doses gradually increased to the maximum tolerated level while monitoring blood pressure 1. The goal is to achieve near-normal pulmonary pressures and improved cardiac output without significant systemic hypotension. Some key points to consider when treating PAH with CCBs include:
- Only about 10-15% of PAH patients are vasoreactive and can benefit from CCBs 1
- CCBs should be avoided in non-responders as they may worsen clinical outcomes 1
- Patients require close monitoring with regular echocardiograms and right heart catheterizations to assess treatment response 1
- If a patient doesn't show sustained improvement or develops side effects like peripheral edema, headache, or significant hypotension, alternative PAH-specific therapies should be considered 1
- Regular follow-up every 3-6 months is essential to evaluate treatment efficacy and adjust therapy as needed 1. CCBs work by blocking calcium influx into vascular smooth muscle cells, causing vasodilation in the pulmonary arteries and reducing pulmonary vascular resistance 1. It is advisable to start with a low dose and increase cautiously and progressively to the maximum tolerated dose, with limiting factors for dose increase being usually systemic hypotension and lower limb peripheral oedema 1.
From the Research
Treatment for Vasoreactive Pulmonary Arterial Hypertension
The treatment for vasoreactive pulmonary arterial hypertension using calcium channel blockers (CCBs) like nifedipine (Adalat) or amlodipine (Norvasc) is as follows:
- CCBs are the first effective therapy for vasoreactive patients with idiopathic pulmonary arterial hypertension (IPAH) 2
- Acute vasoreactivity testing is performed to determine the response to CCB therapy, and patients who show a significant immediate hemodynamic response to pulmonary vasodilators are considered "responders" 3
- The response rate to CCBs is considered to be around 10-15% of patients with idiopathic PAH, and approximately half of these patients will experience long-term benefits with CCBs 4
Improvement in PA Pressure
The improvement in PA pressure after starting CCB therapy is significant, with a decrease in mean pulmonary arterial pressure from 46 to 19.5 mmHg at 1-year follow-up 2
- This improvement is observed in patients who show a positive acute response to vasoreactivity testing using inhaled nitric oxide (NO)
- The use of CCBs in patients with PAH has been shown to reduce right ventricular hypertrophy and improve long-term haemodynamics 5
Key Points
- CCBs are effective in treating vasoreactive PAH, but the response rate is limited to around 10-15% of patients with idiopathic PAH 4
- Acute vasoreactivity testing is essential to determine the response to CCB therapy 2, 3
- Patients who show a positive response to CCBs may experience long-term benefits, including improved haemodynamics and survival 2, 3