Atrial fibrillation modifies the association between pulmonary artery wedge pressure and left ventricular end-diastolic pressure.

AIMS: During right heart catheterization, pulmonary artery wedge pressure (PAWP) is often assumed to reflect left ventricular filling pressure. We sought to determine the impact of atrial fibrillation (AF) on the relationship between PAWP and left ventricular filling pressure, as measured by left ventricular end-diastolic pressure (LVEDP). METHODS AND
RESULTS: We performed simultaneous left and right heart catheterization in 123 patients (mean age 69 years, 28% with AF) referred for suspicion of pulmonary hypertension (PH). The correlation between PAWP and LVEDP was moderate (R2 = 0.42). The relationship between PAWP and LVEDP was modified by heart rhythm (P for interaction <0.01). In sinus rhythm, PAWP underestimated LVEDP (Bland-Altman mean difference: -2.96 mmHg, limits of agreement 6.6 to -12.5; R2  = 0.54), whereas in AF, PAWP overestimated LVEDP (Bland-Altman mean difference: 4.76 mmHg; limits of agreement: 12.2 to -3.3; R2 = 0.58). These differences impacted the differentiation between pre- and post-capillary PH, dependent on the use of either PAWP or LVEDP. In AF, post-capillary PH based on PAWP would have been classified as pre-capillary PH in 35% of patients if based on LVEDP. The opposite is true for sinus rhythm where 31% of pre-capillary PH based on PAWP would have been classified as post-capillary PH if based on LVEDP.
CONCLUSION: The relationship between PAWP and LVEDP varies by heart rhythm, with PAWP being higher than LVEDP among AF patients and lower than LVEDP among patients in sinus rhythm. Rhythm status and influences on the PAWP-LVEDP relationship should be considered when distinguishing between pre-capillary and post-capillary PH.