Optimizing diastolic pressure gradient assessment

The diastolic pressure gradient (DPG) has been proposed as a marker pulmonary vascular disease in the setting of left heart failure (HF). However, its diagnostic utility is compromised by the high prevalence of physiologically incompatible negative values (DPG_NEG) and the contradictory evidence on its prognostic value. Pressure pulsatility impacts on DPG measurements, thus conceivably, pulmonary artery wedge pressure (PAWP) measurements insusceptible to the oscillatory effect of the V-wave might yield a more reliable DPG assessment. We set out to investigate how the instantaneous PAWP at the trough of the Y-descent (PAWP_Y) influences the prevalence of DPG_NEG and the prognostic value of the resultant DPG_Y.

Hundred and fifty-three consecutive HF patients referred for right heart catheterisation were enrolled prospectively. DPG, as currently recommended, was calculated. Subsequently, PAWP_Y was measured and the corresponding DPG_Y was calculated.

DPG_Y yielded higher values (median, IQR: 3.2, 0.6-5.7 mmHg) than DPG (median, IQR: 0.9, - 1.7-3.8 mmHg); p < 0.001. Conventional DPG was negative in 45% of the patients whereas DPG_Y in only 15%. During follow-up (22 ± 14 months) 58 patients have undergone heart-transplantation or died. The predictive ability of DPG_Y ≥ 6 mmHg for the above defined end-point events was significant [HR 2.1; p = 0.007] and independent of resting mean pulmonary artery pressure (PAP_M). In contrast, conventional DPG did not comprise significant prognostic value following adjustment for PAP_M.

Instantaneous pressures at the trough of Y-descent yield significantly fewer DPG_NEG than conventional DPG and entail superior prognostic value in HF patients with and without PH.