Bosentan in heart transplantation candidates with severe pulmonary hypertension: efficacy, safety and outcome after transplantation

Inhaled Iloprost and Oral Sildenafil Combination Therapy: Is it a Chance for Heart Transplant Candidacy?

BACKGROUND

Severe pulmonary hypertension is a risk factor for mortality, due to increased postoperative right ventricular failure, in a heart transplant patient. Elevated pulmonary vascular resistance (PVR) in heart transplant candidates can be reduced using a left ventricular assist device or medical therapy. This study analysed the effect of inhaled iloprost and oral sildenafil combination therapy (ilo-sil) on pulmonary haemodynamic parameters in patients with secondary pulmonary hypertension.

METHODS

Between May 2011 and April 2014, 25 patients who were unresponsive to reversibility test and PVR >3.5 Wood units (WU) during right heart catheterisation were included in this study. After 6 months of oral sildenafil (3 × 20 mg/day) and inhaled iloprost (6 × 5 μg/day) combination therapy, second right heart catheterisations were performed and eligibility for heart transplant was evaluated.

RESULTS

Repeat right heart catheterisation revealed that there was a significant decrease in the PVR from 5.4 ± 1.6 WU to 3.54 ± 2.5 WU (p<0.001), with trans-pulmonary gradient from 13.7 ± 5.6 to 11.46 ± 6.64 (p=0.042), and mean cardiac index (CI) increasing non-significantly from 1.45 ± 0.51 L/min/m2 to 1.82 ± 0.60 (p=0.157). The mean sPAP was initially 57.54 ± 14.79 mmHg and fell to 52.93 ± 16.83 mm Hg (p=0.03). Twenty (20) (80%) patients were enrolled in the waiting list since their PVR values decreased to <3.5 WU. Of these 20 patients, one had undergone heart transplant and four were bridged to transplant with mechanical circulatory support devices.

CONCLUSIONS

After a decrease in PVR with ilo-sil combination therapy for patients with severe pulmonary hypertension, these patients may become candidates for heart transplant without bearing additional risk. Ilo-sil combination therapy could be a viable option with which to evaluate the reversibility of PVR.

Pulmonary arterial hypertension in adults with systemic right ventricles referred for cardiac transplantation

BACKGROUND

Systemic right ventricular (RV) failure may progress necessitating referral for orthotropic heart transplantation (OHT). Pulmonary hypertension (PH) frequently coexists in adult congenital heart disease and can complicate the assessment for OHT.

METHODS

Single-center case series of six patients (median age 34.9 years [IQR, 31.9-42.4]) with systemic RV physiology with PH referred for OHT evaluation from 2008 to 2017.

RESULTS

One-third (n = 6) of 18 patients with systemic RV physiology referred for OHT evaluation had pulmonary arterial hypertension (PAH) defined as mean pulmonary artery pressure (mPAP) > 25 mm Hg and pulmonary vascular resistance (PVR) > 3 Wood Units. Two of the six patients were considered OHT-ineligible due to PH and comorbidities. Of the remaining four, two had pre-capillary PH and underwent heart-lung transplant (HLTx). The other two demonstrated reversibility of PVR with vasodilator testing and underwent OHT alone, one of whom died post-transplant from PH crisis.

CONCLUSIONS

Pulmonary arterial hypertension is common in systemic RV patients referred for OHT. Systemic RV dysfunction places these patients at risk for post-capillary PH but pre-capillary PH can exist. Despite management with selective pulmonary vasodilators and afterload reduction, criteria for listing patients for HLTx vs OHT are not known and need further elucidation.

Predictors of renal replacement therapy after heart transplantation and its impact on long-term survival

BACKGROUND

Renal replacement therapy (RRT) after heart transplant (HT) is associated with worse prognosis. We aimed to identify predictors of RRT and the impact of this complication on long-term survival.

METHODS

Cohort study of HT patients. Univariate and multivariate competing-risk regression was performed to identify independent predictors of RRT. The cumulative incidence function was plotted for RRT. The Kaplan-Meier method was used to compare long-term survival.

RESULTS

We included 103 patients. At multivariate analysis, only the emergency status of HT (short-term mechanical circulatory support as a bridge to transplant), chronic kidney disease, and low oxygen delivery were independent predictors of RRT (subhazard ratio [SHR] 4.11, 95% CI 1.84-9.14; SHR 3.17, 95% CI 1.29-7.77; SHR 2.86, 95% CI 1.14-7.19, respectively). Elective HT patients that required RRT showed a significantly reduced survival comparable to patients with emergency HT and RRT (75% ± 13% vs. 67% ± 16%). The absence of RRT implied an excellent survival in patients with an emergency status of HT and elective HT (100% vs. 93% ± 4%).

CONCLUSION

The emergency status of HT, chronic kidney disease, and low oxygen delivery were independent predictors of RRT. The occurrence of RRT increases the risk of death in elective HT as much as in patients with an emergency status.

Initial experience with bosentan for the management of pulmonary hypertension after heart transplantation

BACKGROUND

Pulmonary hypertension (PH) after heart transplantation (HT) is associated to right ventricular (RV) dysfunction and increased morbidity and mortality. We present our experience with bosentan for the treatment of PH after HT.

METHODS

A retrospective evaluation of patients with PH receiving bosentan post-transplant was performed. Pulmonary hemodynamics before and after bosentan (BG) and clinical outcomes were assessed and compared to a historical control group (CG) not receiving bosentan.

RESULTS

Between 2013 and 2016, 21 patients were treated post-transplant with bosentan. Twenty-four hours after bosentan initiation, there were significant decreases in systolic (42.5 ± 8 to 38.1 ± 8 mm Hg, P = 0.015), diastolic (21.4 ± 4 to 17.8 ± 6 mm Hg, P = 0.008) and mean (29.6 ± 5 to 25 ± 6 mm Hg, P = 0.001) pulmonary artery pressures (PAP), transpulmonary gradient (13.1 ± 3 to 9.7 ± 4 mm Hg, P < 0.001), diastolic gradient (5.2 ± 4 to 2.3 ± 3 mm Hg, P = 0.001) and pulmonary vascular resistance (PVR) (2.2 ± 1 to 1.6 ± 1WU, P = 0.015). This effect was maintained at day 3. Compared with CG, BG showed significantly more decrease in PVR (0.7 ± 0.9 vs 0.3 ± 1.7WU, P = 0.025) and mean PAP (4.6 ± 5.2 vs 1.5 ± 4.4 mm Hg, P = 0.040). RV function 7 days post-transplant was significantly better in BG compared to CG, P = 0.004. There were not clinically significant interactions between bosentan and immunosuppressive treatment.

CONCLUSIONS

Bosentan, initiated early post-transplant, was associated with a significant decrease in PVR. Bosentan was well tolerated and did not interact with immunosuppressive treatment.

Pulmonary hypertension due to left heart disease causes intrapulmonary venous arterialization in rats

OBJECTIVE

A rat model of left atrial stenosis-associated pulmonary hypertension due to left heart diseases was prepared to elucidate its mechanism.

METHODS

Five-week-old Sprague-Dawley rats were randomly divided into 2 groups: left atrial stenosis and sham-operated control. Echocardiography was performed 2, 4, 6, and 10 weeks after surgery, and cardiac catheterization and organ excision were subsequently performed at 10 weeks after surgery.

RESULTS

Left ventricular inflow velocity, measured by echocardiography, significantly increased in the left atrial stenosis group compared with that in the sham-operated control group (2.2 m/s, interquartile range [IQR], 1.9-2.2 and 1.1 m/s, IQR, 1.1-1.2, P < .01), and the right ventricular pressure-to-left ventricular systolic pressure ratio significantly increased in the left atrial stenosis group compared with the sham-operated control group (0.52, IQR, 0.54-0.60 and 0.22, IQR, 0.15-0.27, P < .01). The right ventricular weight divided by body weight was significantly greater in the left atrial stenosis group than in the sham-operated control group (0.54 mg/g, IQR, 0.50-0.59 and 0.39 mg/g, IQR, 0.38-0.43, P < .01). Histologic examination revealed medial hypertrophy of the pulmonary vein was thickened by 1.6 times in the left atrial stenosis group compared with the sham-operated control group. DNA microarray analysis and real-time polymerase chain reaction revealed that transforming growth factor-β mRNA was significantly elevated in the left atrial stenosis group. The protein levels of transforming growth factor-β and endothelin-1 were increased in the lung of the left atrial stenosis group by Western blot analyses.

CONCLUSIONS

We successfully established a novel, feasible rat model of pulmonary hypertension due to left heart diseases by generating left atrial stenosis. Although pulmonary hypertension was moderate, the pulmonary hypertension due to left heart diseases model rats demonstrated characteristic intrapulmonary venous arterialization and should be used to further investigate the mechanism of pulmonary hypertension due to left heart diseases.

Neurohormonal Blockade in Heart Failure

A key feature of chronic heart failure (HF) is the sustained activation of endogenous neurohormonal systems in response to impaired cardiac pumping and/or filling properties. The clinical use of neurohormonal blockers has revolutionised the care of HF patients over the past three decades. Drug therapy that is active against imbalance in both the autonomic and renin-angiotensin-aldosterone systems consistently reduces morbidity and mortality in chronic HF with reduced left ventricular ejection fraction and in sinus rhythm. This article provides an assessment of the major neurohormonal systems and their therapeutic blockade in patients with chronic HF.

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.

The state of the art in heart transplantation

Cardiac transplantation is in its fourth decade as a treatment for end-stage cardiomyopathy and heart failure. It has reached a mature stage in its development as an effective treatment and many issues are settled with respect to best practices. However, there are many areas of ongoing research and significant advances that are continually being recognized. What constitutes 'State of the Art' in heart transplantation? This review focuses on developments in the pretransplant, peritransplant, and posttransplant phases of the care of the potential heart transplant recipient.

Acute pulmonary vasoreactivity test with sildenafil or nitric monoxide before left ventricular assist device implantation

There has been no established medical therapy to ameliorate pulmonary hypertension (PH) owing to left heart disease (LHD-PH). It has recently been shown that the left ventricular assist device (LVAD) can improve LHD-PH and therefore has the potential to become a major bridge tool for heart transplantation (HTx). However, some patients still have persistent PH even after LVAD treatment. It is essential to demonstrate the reversibility of end-organ dysfunction, including PH, prior to implantable LVAD treatment, especially in Japan, because implantable LVAD treatment is indicated only as bridge to transplantation. Here we report a patient with LHD-PH whose PH was demonstrated to be reversible by the acute pulmonary vasoreactivity test (APVT) with nitrogen monoxide (NO) and the phosphodiesterase-5 inhibitor sildenafil. Both inhaled NO and sildenafil reduced pulmonary vascular resistance, but pulmonary capillary wedge pressure was increased by NO, which was conversely decreased under increased cardiac output by sildenafil. After the patient was listed as an HTx recipient, pulmonary vascular resistance recovered down to an acceptable range with LVAD treatment. Based on these findings, we suggest that the APVT with sildenafil may be a useful and safe tool to predict improvement of PH after LVAD treatment.

Effect of bosentan on pulmonary hypertension secondary to systolic heart failure

OBJECTIVES

The dual endothelin receptor antagonist bosentan improves pulmonary vascular resistance (PVR) in patients with primary pulmonary hypertension (PH). The effects of bosentan on secondary PH due to systolic heart failure (HF) are not well defined. This study evaluates the effect and tolerability of bosentan in patients with PH secondary to HF.

METHODS

Seventeen adult HF patients with PH and New York Heart Association class III-IV symptoms were treated with bosentan, 62.5 mg twice daily, for 1 month, which was gradually increased to 125 mg twice daily thereafter. Right heart catheterization (RHC), a clinical evaluation and echocardiographic measurements were performed at baseline and at 4 ± 3 (mean ± SD) months of follow-up. Response to bosentan was defined as an improvement in clinical, echocardiographic and RHC parameters.

RESULTS

Six patients did not complete the study (therapy was discontinued due to hypotension, elevated liver enzymes or acute decompensation of HF), 11 patients completed the follow-up; 9 patients responded to therapy. Systemic arterial pressures, pulmonary pressures, PVR and the transpulmonary gradient significantly decreased compared with baseline levels in 9 responders (p = 0.05, 0.05, 0.01 and 0.004, respectively), and 4 became eligible for heart transplantation and 3 for left ventricular assist device implantation.

CONCLUSIONS

Bosentan decreased pulmonary pressures and PVR in the majority of patients with PH secondary to systolic HF, thereby allowing them to be considered candidates for heart transplantation.