Is a pulmonary acceleration time of 114 milliseconds indicative of pulmonary hypertension?

Pulmonary Acceleration Time of 114 msec and Pulmonary Hypertension

A pulmonary acceleration time (PAcT) of 114 msec does not indicate pulmonary hypertension according to current guidelines, as it exceeds the threshold value of 105 msec that is used as an echocardiographic sign suggesting pulmonary hypertension. 1

Understanding Pulmonary Acceleration Time in Pulmonary Hypertension Assessment

• According to the 2015 ESC/ERS guidelines, right ventricular outflow Doppler acceleration time <105 msec and/or midsystolic notching is considered an echocardiographic sign suggesting pulmonary hypertension 1
• Pulmonary acceleration time is one of several echocardiographic parameters used to assess the probability of pulmonary hypertension, particularly when tricuspid regurgitation velocity measurement may be difficult or unavailable 1
• PAcT represents the time from the onset of systolic flow to peak velocity in the right ventricular outflow tract and correlates with mean pulmonary artery pressure 2

Interpretation of Your PAcT Value

• Your PAcT value of 114 msec is above the cutoff of 105 msec established in the guidelines, suggesting normal pulmonary pressures 1
• For context, studies have shown that a PAcT less than 90 msec has an 84% positive predictive value for pulmonary hypertension 2
• Another study demonstrated that PAcT ≤90 ms had an 84% sensitivity and 85% specificity in identifying patients with pulmonary vascular resistance ≥3 Wood Units 3

Comprehensive Assessment Beyond PAcT

• While your PAcT value does not suggest pulmonary hypertension, it's important to note that echocardiographic assessment of pulmonary hypertension should include multiple parameters 1
• The ESC/ERS guidelines recommend using signs from at least two different categories (ventricles, pulmonary artery, and inferior vena cava/right atrium) to alter the level of echocardiographic probability of pulmonary hypertension 1
• Tricuspid regurgitation velocity (TRV) remains the primary parameter for assessing the probability of pulmonary hypertension, with PAcT serving as a supplementary measure 1

Clinical Implications

• In the absence of other echocardiographic signs suggesting pulmonary hypertension, a PAcT of 114 msec would classify the echocardiographic probability of pulmonary hypertension as low 1
• For patients with low echocardiographic probability of pulmonary hypertension and no risk factors, alternative diagnoses should be considered 1
• If clinical suspicion remains high despite the normal PAcT, additional echocardiographic parameters should be evaluated, including TRV, right ventricular/left ventricular basal diameter ratio, interventricular septal flattening, and right atrial area 1

Limitations and Considerations

• The relationship between PAcT and pulmonary vascular resistance is non-linear, with a quadratic correlation (r = 0.61) 3
• No single Doppler method is simultaneously easily applicable and accurate in predicting pulmonary arterial pressure in all patients, particularly those with chronic lung diseases 2
• In some cases, sufficient quality echocardiographic signals may not be obtained, limiting the reliability of PAcT measurement 4
• The gold standard for diagnosis of pulmonary hypertension remains right heart catheterization, which should be considered when clinical suspicion is high despite normal echocardiographic findings 1