What is it called when pulmonary artery (PA) pressure decreases from a mean of 72 mmHg to 58 mmHg, is that considered a responder to vasoreactivity testing?

Pulmonary Vasoreactivity Testing Response Criteria

A decrease in mean pulmonary artery pressure (mPAP) from 72 mmHg to 58 mmHg does not meet the criteria for a positive vasoreactive response according to current guidelines. 1

Definition of a Positive Vasoreactive Response

According to current guidelines, a positive vasoreactive response is defined by specific criteria:

• A decrease in mean pulmonary artery pressure (mPAP) by ≥10 mmHg
• To reach an absolute value of mPAP ≤40 mmHg
• Without a decrease in cardiac output (CO) 1

In this case:

• The decrease from 72 mmHg to 58 mmHg represents a 14 mmHg reduction (meets the first criterion)
• The final mPAP of 58 mmHg is still above the required threshold of ≤40 mmHg (fails the second criterion)
• No information is provided about cardiac output (third criterion cannot be evaluated)

Clinical Significance of Vasoreactivity Testing

Vasoreactivity testing has important therapeutic implications:

• Only patients who meet all criteria for a positive response should be considered for high-dose calcium channel blocker (CCB) therapy 1
• Less than 15% of idiopathic PAH patients are deemed responders during testing 1
• Even fewer exhibit long-term responsiveness to CCBs 1

Evolution of Response Criteria

The definition of vasoreactivity has evolved over time:

• Earlier criteria defined a positive response as a 20% decrease in both mPAP and PVR 1
• Current consensus definition (≥10 mmHg decrease to reach mPAP ≤40 mmHg with unchanged/increased CO) is more specific in identifying patients who will benefit from CCB therapy 1, 2

Implications for Treatment

For this patient with a decrease from 72 mmHg to 58 mmHg:

• This represents a partial response but does not qualify as a "responder" by current guidelines
• CCB therapy would not be recommended based on these results 1
• PAH-specific therapies should be considered instead 1

Prognostic Significance

Despite not meeting criteria for CCB therapy:

• Any degree of vasoreactivity may still have prognostic significance
• Independent of whether CCBs are started, vasoreactivity to inhaled nitric oxide predicts better long-term survival in pulmonary arterial hypertension 1
• Recent research suggests that pulmonary artery compliance during testing may provide additional prognostic information 3

Important Considerations in Vasoreactivity Testing

• Testing should be performed using inhaled nitric oxide as the preferred vasodilator 1
• Alternative agents include IV epoprostenol or IV adenosine 1
• Testing should only be performed at specialized centers with experience in interpretation 1
• Contraindications include low systemic blood pressure, low cardiac output, or WHO functional class IV symptoms 1

In conclusion, while this patient showed some degree of pulmonary vascular reactivity (14 mmHg decrease), they would not be classified as a "responder" according to current guidelines and would not be a candidate for CCB therapy based on these results.