Use of oral sildenafil in patients with irreversible pulmonary hypertension not eligible for heart transplantation

Safety and Efficacy of Sildenafil for Group 2 Pulmonary Hypertension in Left Heart Failure

Pulmonary hypertension (PH) is a multifactorial, progressive disease with poor outcomes. Group 2 PH is defined by pulmonary vascular disease with elevated pulmonary capillary wedge pressure including both left-sided obstructive lesions and diastolic heart failure (HF). Sildenafil was historically discouraged in this population as pulmonary vasodilation can lead to pulmonary edema. However, evidence suggests that sildenafil can help to treat the precapillary component of PH. This is a single center, retrospective pilot study of pediatric PH patients with left-sided HF who were treated with sildenafil for ≥ 4 weeks. HF patients without mechanical support (HF group) and HF patients with a left ventricular assist device (HF-VAD) were analyzed. The exploratory analysis described the safety and side effects of the drug. Echocardiographic parameters were compared before and after sildenafil treatment in a paired analysis. The changes in medical therapy during treatment, mechanical support, and mortality was reported; 19/22 patients tolerated sildenafil. Pulmonary edema in two patients resolved upon discontinuation of sildenafil. In the HF group, both the right atrial volume and right ventricular diastolic area decreased, and the tricuspid regurgitation (TR) S/D ratio decreased after therapy (p = 0.02). Across both the groups, four patients weaned off milrinone and seven weaned off inhaled nitric oxide. Of the thirteen HF patients, four received a transplant, and all of the nine HF-VAD patients received a transplant. Sildenafil can be safely used in carefully selected patients with HF and mixed pre/postcapillary PH with judicious titration and inpatient surveillance, with patients showing improvements in echocardiographic parameters.

Pulmonary vascular resistance as a potential marker of reactive pulmonary hypertension reduction following sildenafil therapy in patients disqualified from orthotopic heart transplantation

PURPOSE

We sought to determine the predictors of restoration of heart transplantation (HTx) candidacy in patients with systolic heart failure (HF) and reactive fixed pulmonary hypertension (RFPH) defined as pulmonary vascular resistance (PVR) > 2.5 Wood units (WU), transpulmonary gradient (TPG) > 12 mmHg or ≤2.5 WU with systolic arterial pressure ≤85 mmHg during vasoreactivity test, following sildenafil therapy.

MATERIAL AND METHODS

Between 2007 and 2018 1136 patients were evaluated at our department as candidates for HTx. Thirty-five of them, who presented with systolic HF and were not eligible for HTx due to RFPH, were included in the study (31 men aged 55.1 ± 7.4 years). In all the patients sildenafil was introduced and up-titrated to a maximal tolerated dose in addition to optimal medical therapy. Patients were assessed at 3-6 months intervals.

RESULTS

During median 11 months (interquartile range 6-18 months) reduction of RFPH enabling qualification for HTx was observed in 62.9% patients. Higher baseline PVR (OR 0.32; 95% CI (0.14-0.74) p < 0.001), pulmonary artery systolic pressure (PASP) (OR 0.94, 95% CI (0.88-0.99) p = 0.05), mean artery pulmonary pressure (mPAP) (OR 0.87, 95% CI (0.77-0.98) p = 0.02) and TPG (OR 082, 95% CI (0.70-0.96) p = 0.003) were negative predictors of RFPH reduction with sildenafil therapy. In multivariable analysis, lower PVR (p = 0.02) was identified as an independent predictor of RFPH reduction following sildenafil therapy.

CONCLUSION

Sildenafil therapy can support PH reduction in systolic HF patients uneligible for HTx due to RFPH. Lower baseline PVR was identified as an independent predictor of PH reversibility with sildenafil enabling restoration of HTx candidacy.

Pathophysiology and potential treatments of pulmonary hypertension due to systolic left heart failure

Pulmonary hypertension (PH) due to left heart failure is becoming increasingly prevalent and is associated with poor outcome. The precise pathophysiological mechanisms behind PH due to left heart failure are, however, still unclear. In its early course, PH is caused by increased left ventricular filling pressures, without pulmonary vessel abnormalities. Conventional treatment for heart failure may partly reverse such passive PH by optimizing left ventricular function. However, if increased pulmonary pressures persist, endothelial damage, excessive vasoconstriction and structural changes in the pulmonary vasculature may occur. There is, at present, no recommended medical treatment for this active component of PH due to left heart failure. However, as the vascular changes in PH due to left heart failure may be similar to those in pulmonary arterial hypertension (PAH), a selected group of these patients may benefit from PAH treatment targeting the endothelin, nitric oxide or prostacyclin pathways. Such potent pulmonary vasodilators could, however, be detrimental in patients with left heart failure without pulmonary vascular pathology, as selective pulmonary vasodilatation may lead to further congestion in the pulmonary circuit, resulting in pulmonary oedema. The use of PAH therapies is therefore currently not recommended and would require the selection of suitable patients based on the underlying causes of the disease and careful monitoring of their progress. The present review focuses on the following: (i) the pathophysiology behind PH resulting from systolic left heart failure, and (ii) the current evidence for medical treatment of this condition, especially the role of PAH-targeted therapies in systolic left heart failure.

Sildenafil, a PDE5 inhibitor, in the treatment of pulmonary hypertension

Pulmonary hypertension is a devastating disorder, characterized by vascular proliferation, intimal hypertrophy and vasoconstriction. In this disorder, alterations in the nitric oxide pathway have borne out to be important in not only vascular proliferation, but also in the maintenance of vascular tone. After synthesis by soluble guanylate cyclase, cGMP effects vasodilation via protein kinase G and other mediators, and is hydrolyzed by phosphodiesterases (PDEs). PDE5 is abundantly expressed in the mammalian lung and its inhibition by sildenafil has been demonstrated to improve pulmonary vascular physiology in vitro and in vivo animal models of pulmonary hypertension. Recent human data has confirmed the efficacy of sildenafil in therapy for humans with pulmonary arterial hypertension. The following review will discuss the underlying basic science supporting the use of sildenafil, as well as human evidence supporting the critical role of this drug in therapy of patients with pulmonary hypertension.

Impact of pulmonary hypertension on early hemodynamics, morbidity and mortality after orthotopic heart transplantation. A single center study

AIMS

To determine the effect of pre-existing pulmonary hypertension (PHT) on early hemodynamics, morbidity and mortality after heart transplantation (HTx).

METHODS

Data were prospectively collected from 149 patients, who underwent HTx between January 2000 and December 2007. The subjects were divided into 3 groups: Group A (n=84) without PTH, group B (n=50) with mild to moderate PTH and group C (n=15) with severe PTH. We studied hemodynamic profile, tricuspid valve regurgitation (TR), incidence of acute cellular rejections (AR), infections, duration of hospitalization, 30-day mortality and a long-term survival.

RESULTS

Baseline characteristics were similar in all groups. Using vasodilator treatment PVR was successfully brought down to normal range 2.5 ± 0.6 Wood' units (WU) on the day 1 following the surgery in all groups. Over 80% of patients were treated in Group C, 32% in Group A and 46% in Group B. There was no significant difference in the severity of TR among the 3 groups early after HTx (severe TR was observed in 46%, 54%, 33%, respectively). There was no significant difference in incidence of AR (G ≥ 2 Banff classification) (23%, 23%, 33%, respectively), infections (28%, 32%, 33%, respectively) or duration of hospitalization (30, 30, 28 days, respectively). There was no correlation between pre-transplant PHT and 30-day mortality or a long-term survival.

CONCLUSIONS

In our cohort, PHT dropped very quickly after HTx, and was not associated with acute right heart failure following the surgery. Reversible PTH does not have a negative impact on short- or long-term survival after HTx.

PDE5A inhibitor treatment of persistent pulmonary hypertension after mechanical circulatory support

BACKGROUND

Pulmonary hypertension (PH) secondary to left heart failure portends a poor prognosis and is a relative contraindication to heart transplantation at many centers. We tested the hypothesis that when PH persists after adequate left ventricle unloading via recent left ventricular assist device (LVAD) therapy, phosphodiesterase type 5A inhibition would decrease PH in this population.

METHODS AND RESULTS

We performed an open-label clinical trial using control patients not receiving therapy. Between 1999 and 2007, 138 consecutive patients undergoing cardiac transplantation evaluation with advanced left ventricular dysfunction, an elevated pulmonary capillary wedge pressure, and PH (defined by a pulmonary vascular resistance (PVR) >3 Woods Units), were treated with LVAD therapy. Fifty-eight of these patients reduced their pulmonary capillary wedge pressure to a value <15 mm Hg (11.8+/-2.0 mm Hg from baseline 23.2+/-6.2 mm Hg) 1 to 2 weeks after LVAD implantation, but despite this improvement, the PVR of these patients was only minimally affected (5.65+/-3.00 to 5.39+/-1.78 Wood Units). Twenty-six consecutive patients from this group with persistently elevated PVR were started on oral phosphodiesterase type 5A inhibition with sildenafil and titrated to an average of dose of 51.9 mg by mouth 3 times per day. The average PVR in the sildenafil-treated group fell from 5.87+/-1.93 to 2.96+/-0.92 Wood Units (P<0.001) and the mean pulmonary artery pressure fell from 36.5+/-8.6 to 24.3+/-3.6 mm Hg (P<0.0001) and was significantly lower when compared with the 32 LVAD recipients not receiving sildenafil at weeks 12 to 15 after the initial post-LVAD hemodynamic measurements (13 to 17 weeks post-LVAD implantation). In addition, hemodynamic measurements of right ventricular function in sildenafil-treated patients was also improved compared with patients not receiving sildenafil.

CONCLUSIONS

In patients with persistent PH after recent LVAD placement, phosphodiesterase type 5A inhibition in this open-label trial resulted in a significant decrease in PVR when compared with control patients.

Persistent tricuspid regurgitation and its predictor in adults after percutaneous and isolated surgical closure of secundum atrial septal defect

The fate of functional tricuspid regurgitation (TR) after closure of a secundum atrial septal defect (ASD) without any corrective tricuspid valve (TV) surgery remains unclear. We investigated this and the predictors of persistent TR after ASD closure. Thirty-two consecutive patients with moderate or severe TR before ASD closure were examined. Of these, 23 underwent percutaneous ASD closure, and 9 underwent isolated surgical ASD closure. The left ventricular end-diastolic volume, left ventricular ejection fraction, right ventricular end-diastolic area, right ventricular fractional area change, right ventricular spherical index, right atrial area, TV annular diameter, TV tethering height, pulmonary artery systolic pressure, and pulmonary/systemic blood flow ratio were determined by echocardiography before and early after ASD closure. The color Doppler maximal jet area was used to assess the severity of TR. After ASD closure, the jet area decreased for all patients (p = 0.009); however, 16 patients (50%) had persistent TR. Multivariate analysis revealed that only pulmonary artery systolic pressure before ASD closure was related to the TR jet area after ASD closure (p = 0.003). A pulmonary artery systolic pressure of >60 mm Hg predicted persistent TR with 100% sensitivity and 63% specificity. In conclusion, functional TR was ameliorated after percutaneous and isolated surgical ASD closure, although persistent TR was common. The presence of pulmonary hypertension before ASD closure predicted persistent TR; therefore, corrective TV surgery should be considered at ASD closure in adult patients with moderate or severe TR and concomitant pulmonary hypertension.

Different determinants of residual tricuspid regurgitation after tricuspid annuloplasty: comparison of atrial septal defect and mitral valve prolapse

We analyzed 20 patients with atrial septal defect (ASD) who underwent tricuspid valve (TV) annuloplasty and ASD closure, 21 patients with mitral valve prolapse (MVP) who underwent mitral valve (MV) and TV annuloplasty, and 20 healthy controls. Severity of tricuspid regurgitation (TR) was assessed by maximal TR jet area/RA area (%TR) using echocardiography before and early after surgery. Before surgery, 2 groups of patients showed significantly greater RA area, TV annulus diameter, RV systolic pressure, and %TR than controls. %TR was significantly decreased after surgery, whereas residual TR was shown in 19% of the MVP group and 25% of the ASD group. Preoperative TV tethering height and %TR were significantly associated with postoperative %TR in the MVP group, whereas preoperative RV fractional area change, RV spherical index, and RV systolic pressure were significantly associated with postoperative %TR in the ASD group. Risk stratification after TV annuloplasty should take the structural abnormality into consideration.

Prognosis after heart transplant in patients with pulmonary hypertension secondary to cardiopathy

INTRODUCTION

Pulmonary hypertension (PHT) is associated with greater posttransplant mortality. In the last few years, many vasodilator drugs have been developed and some patients have therefore been transplanted. However, conflicting data exist regarding the impact of reversible PHT on posttransplant outcomes. The aim of this study was to determine the evolution of our transplanted patients with reactive PHT and the causes of right cardiac insufficiency and perioperative mortality.

MATERIAL AND METHODS

We performed a retrospective analysis of 39 consecutive heart transplant recipients from January 2005 to December 2006. We analyzed significant pretransplant PHT, the percentage of emergency transplants, surgical technique, as well as ischemia and extracorporeal circulation times.

RESULTS

Before transplantation, significant PHT was present in 12 patients (30.8%), all of whom had a positive acute vasoreactivity test or response to oral treatment with pulmonary vasodilators. A nonsignificant tendency to increased posttransplant mortality was observed among patients with pretransplant PHT. We observed a significant increase in mortality in patients with prolonged operative times, over the third percentile, odds ratio (OR) for ECC of 21% (P = .001) and OR for prolonged ischemia time of 9.5% (P = .022). However, mortality did not increase significantly in cases of emergent transplantation (P = .08) or in the use of the Shumway bicaval surgical technique (P = .9).

CONCLUSIONS

There seemed to be a slight tendency to increased mortality among patients with reversible HTP, suggesting that high-risk patients need closer monitoring but are not absolutely contraindicated for transplantation.

Complex multidrug therapy in a patient with pulmonary hypertension before and after orthotopic heart transplantation. A case report

Pulmonary arterial hypertension represents an absolute contraindication for heart transplantation. We report the case of a 30-year-old man with end-stage heart failure due to restrictive cardiomyopathy and pulmonary arterial hypertension. A complex multidrug therapy improved pulmonary haemodynamics to the point that orthotopic heart transplantation could be carried out. At 18-month follow-up after heart transplantation, the patient's cardiac function made a full recovery. Larger prospective studies are warranted to support these results.

Sildenafil in the treatment of pulmonary hypertension

The therapy of pulmonary hypertension has evolved rapidly in the last 10 years from the use of non-selective vasodilators to drugs that specifically target pulmonary vasodilation, endothelial function, and vascular remodeling. Sildenafil is a phosphodiesterase type 5 inhibitor that has an expanding role in the treatment of pulmonary hypertension. Case series and small studies, as well as the first large randomized controlled trial, have demonstrated the safety and efficacy of sildenafil in improving mean pulmonary artery pressure, pulmonary vascular resistance, cardiac index, and exercise tolerance in pulmonary arterial hypertension. It may be useful in adults, children, and neonates after cardiac surgery, with left heart failure, in fibrotic pulmonary disease, high altitude exposure, and thromboembolic disease, and in combination with other therapies for pulmonary hypertension, such as inhaled iloprost. The oral formulation and favorable adverse effect profile make sildenafil an attractive alternative in the treatment of selected patients with pulmonary hypertension.

Combination Therapy With Sildenafil and Bosentan Reverts Severe Pulmonary Hypertension and Allows Heart Transplantation: Case Report

INTRODUCTION

Severe pulmonary hypertension with no response to vasodilators on an acute hemodynamic study is a contraindication to cardiac transplantation. The development of oral pulmonary vasodilators improves the prognosis in these patients. We present the case of a patient whose admission to the waiting list for cardiac transplantation was possible after 6 months of combination therapy with Sildenafil and Bosentan.

CASE REPORT

The patient was a 50-year-old man with severe dilated alcohol-induced cardiomyopathy. A pretransplantation study, including a right hemodynamic analysis, revealed irreversible pulmonary hypertension, with 59 mm Hg mean pulmonary artery pressure and 6.4 Wood IU pulmonary vascular resistance, with no response to acute vasodilators with nitric oxide or prostacyclin. Initially, heart transplantation was not possible and the patient started treatment with oral Sildenafil. After 6 months there was no improvement in echocardiographic or hemodynamic parameters, and combination therapy with Bosentan was started. With the combination therapy, the patient progressively improved clinically and hemodynamically, the pressures becoming normal at the sixth month, at which time he was included on the waiting list for a heart transplantation. Eight months later he received a graft with a good posttransplantation course, no right ventricular failure in the acute phase, and absence of pulmonary hypertension on echocardiogrphic and invasive studies.

CONCLUSION

Combinations of an oral pulmonary vasodilator with diverse action mechanisms may represent an alternative for patients with irreversible pulmonary hypertension who do not respond to monotherapy.

Initial experience with bosentan therapy in patients considered ineligible for heart transplantation because of severe pulmonary hypertension

BACKGROUND

Pre-operative elevated pulmonary vascular resistance (PVR) has been associated with increased right ventricular failure and mortality after heart transplantation. The aim of this study was to assess the efficacy of bosentan, an oral endothelin-receptor antagonist, to reduce PVR in patients considered ineligible for heart transplantation because of severe pulmonary hypertension.

METHODS

Seven patients with end-stage congestive heart failure and considered ineligible for heart transplantation because of severe pulmonary hypertension (PVR>2.5 Wood units after nitroprusside infusion) were included in the study. They received bosentan 62.5 mg b.i.d. for four wk and 125 mg b.i.d. thereafter. Right heart catheterization was repeated after six wk of therapy.

RESULTS

After six wk of bosentan therapy, there was a significant decrease in PVR (6.0 +/- 2 vs. 3.8 +/- 2 Wood units, before vs. after bosentan; p = 0.02), in PVR during nitroprusside infusion (3.3 +/- 1 vs. 2.1 +/- 1 Wood units, before vs. after bosentan; p = 0.02) and in diastolic pulmonary artery pressure (33 +/- 7 vs. 23 +/- 7 mmHg, before vs. after bosentan; p = 0.04). No significant adverse events were observed. After bosentan therapy, five patients had PVR<or=2.5 Wood units. They were included in the waiting list and all five had a successful heart transplantation, although two of them required bosentan after surgery.

CONCLUSIONS

In patients considered ineligible for heart transplantation because of high PVR, bosentan therapy significantly reduced PVR. These data suggest that therapy with endothelin-receptor blockers might be useful to identify a subgroup of patients with high PVR who can benefit from heart transplantation.