Sodium Nitroprusside in Patients With Mixed Pulmonary Hypertension and Left Heart Disease: Hemodynamic Predictors of Response and Prognostic Implications.

Background: Mixed pulmonary hypertension (PH) in heart failure (HF) is defined by transpulmonary gradient ≥ 12 and/or pulmonary vascular resistance (PVR) ≥ 240 dyne/s/cm(-5), but diastolic pressure gradient (DPG) ≥ 7 mmHg has been proposed more recently. We evaluated the acute hemodynamic response to sodium nitroprusside (SNP) specifically in relation to the proposed DPG criterion ≥7 mmHg and the prognostic significance of response to SNP in patients with mixed PH and advanced HF.

Methods: Ninety-eight consecutive patients with advanced HF and mixed PH underwent cardiac catheterization and acute SNP infusion. Baseline hemodynamic parameters included transpulmonary gradient, PVR, DPG, and pulmonary capacitance (PCap). Hemodynamic response to SNP was defined as a reduction in PVR of at least 20%. The composite endpoint was death/heart transplantation/mechanical circulatory support.

Results: Sixty of the 98 patients were SNP responders. SNP resulted in significant reductions in filling pressures and PVR and increase in stroke volume and PCap. DPG (not baseline PVR) was significantly associated with hemodynamic response to SNP on logistic regression analysis. The sensitivity and specificity of a DPG ≥7 mmHg to identify nonresponders to SNP were 74% and 97%, respectively. At median follow-up of 218 (148-324) days, 13 and 19 patients of the SNP responders and nonresponders, respectively, met the composite endpoint (P = .021 by log-rank test). Hemodynamic response to SNP and PCap were independently associated with the composite outcome of survival free from transplantation/mechanical circulatory support.

Conclusion: Baseline DPG ≥ 7 mmHg is associated with poor PVR response to SNP. PVR response to SNP and PCap are associated with a more favorable prognosis in patients with advanced HF and mixed PH.