Acute Unloading Effects of Sildenafil Enhance Right Ventricular-Pulmonary Artery Coupling in Heart Failure.

BACKGROUND: Phosphodiesterase-5A inhibitors (PDE5i) are sometimes used in patients with advanced heart failure with reduced ejection fraction before heart transplant or left ventricular assist device implantation to decrease right ventricular (RV) afterload and mitigate the risk of right heart failure. Conflicting evidence exists regarding the impact of these drugs on RV contractility. The aim of this study was to explore the acute effects of PDE5i on ventricular-vascular coupling and load-independent RV contractility. METHODS: Twenty-two patients underwent right heart catheterization and gated equilibrium blood pool single photon emission computed tomography, before and after 20 mg intravenous sildenafil. Single photon emission computed tomography and right heart catheterization-derived data were used to calculate RV loading and contractility. RESULTS: PDE5i induced a decrease in the right atrial pressure (-43%), pulmonary artery (PA) mean pressure (-26%), and PA wedge pressure (PAWP; -23%), with favorable reductions in pulmonary vascular resistance (-41%) and PA elastance (-40%), and increased cardiac output (+13%) (all P < 0.01). The RV ejection fraction increased with sildenafil (+20%), with no change of RV contractility (P = 0.74), indicating that the improvement in the RV ejection fraction was related to enhanced RV-PA coupling (r = 0.59, P = 0.004) by a decrease in the ventricular load. RV diastolic compliance increased with sildenafil. The decrease in the PAWP correlated with RV end-diastolic volume decrease; no relationship was observed with the change in LV transmural pressure, suggesting decreased pericardial constraint. CONCLUSIONS: Acute PDE5i administration has profound RV afterload-reducing effects, improves the RVEF, decreases RV volumes, and decreases the PAWP, predominantly through relief of pericardial constraint, without effects on RV chamber contractility. These findings support further study of PDE5i in protection of RV function in advanced heart failure with reduced ejection fraction who are at risk of RV failure.

Pressure overload is associated with right ventricular dyssynchrony in heart failure with reduced ejection fraction.

AIMS: The determinants and relevance of right ventricular (RV) mechanical dyssynchrony in heart failure with reduced ejection fraction (HFrEF) are poorly understood. We hypothesized that increased afterload may adversely affect the synchrony of RV contraction. METHODS AND RESULTS: A total of 148 patients with HFrEF and 36 controls underwent echocardiography, right heart catheterization, and gated single-photon emission computed tomography to measure RV chamber volumes and mechanical dyssynchrony (phase standard deviation of systolic displacement timing). Exams were repeated after preload (N = 135) and afterload (N = 15) modulation. Patients with HFrEF showed higher RV dyssynchrony compared with controls (40.6 ± 17.5° vs. 27.8 ± 9.1°, P < 0.001). The magnitude of RV dyssynchrony in HFrEF correlated with larger RV and left ventricular (LV) volumes, lower RV ejection fraction (RVEF) and LV ejection fraction, reduced intrinsic contractility, increased heart rate, higher pulmonary artery (PA) load, and impaired RV-PA coupling (all P ≤ 0.01). Low RVEF was the strongest predictor of RV dyssynchrony. Left bundle branch block (BBB) was associated with greater RV dyssynchrony than right BBB, regardless of QRS duration. RV afterload reduction by sildenafil improved RV dyssynchrony (P = 0.004), whereas preload change with passive leg raise had modest effect. Patients in the highest tertiles of RV dyssynchrony had an increased risk of adverse clinical events compared with those in the lower tertile [T2/T3 vs. T1: hazard ratio 1.98 (95% confidence interval 1.20-3.24), P = 0.007]. CONCLUSIONS: RV dyssynchrony is associated with RV remodelling, dysfunction, adverse haemodynamics, and greater risk for adverse clinical events. RV dyssynchrony is mitigated by acute RV afterload reduction and could be a potential therapeutic target to improve RV performance in HFrEF.

Right ventricular global dysfunction score: a new concept of right ventricular function assessment in patients with heart failure with reduced ejection fraction (HFrEF).

Background: Right ventricular (RV) function is currently being evaluated solely according to the properties of RV myocardium. We have tested a concept that in patients with heart failure with reduced ejection fraction (HFrEF), RV assessment should integrate the information about both RV function as well as size. Methods: A total of 836 stable patients with HFrEF (LVEF 23.6 ± 5.8%, 82.8% males, 68% NYHA III/IV) underwent echocardiographic evaluation and were prospectively followed for a median of 3.07 (IQRs 1.11; 4.89) years for the occurrence of death, urgent heart transplantation or implantation of mechanical circulatory support. Results: RV size (measured as RV-basal diameter, RVD1) was significantly associated with an adverse outcome independent of RV dysfunction grade (p = 0.0002). The prognostic power of RVD1 was further improved by indexing to body surface area (RVD1i, p < 0.05 compared to non-indexed value). A novel parameter named RV global dysfunction score (RVGDs) was calculated as a product of RVD1i and the degree of RV dysfunction (1-4 for preserved RV function, mild, moderate and severe dysfunction, respectively). RVGDs showed a superior prognostic role compared to RV dysfunction grade alone (ΔAUC >0.03, p < 0.0001). In every subgroup of RVGDs (<20, 20-40, 40-60, >60), patients with milder degree of RV dysfunction but more dilated RV had similar outcome as those with more severe degree of RV dysfunction but smaller RV size (all p > 0.50), independent of tricuspid regurgitation severity and degree of pulmonary hypertension. Conclusion: RV dilatation is a manifestation of RV dysfunction. The evaluation of RV performance should integrate the information about both RV size and function.