Prognostic value of the pre-transplant diastolic pulmonary artery pressure-to-pulmonary capillary wedge pressure gradient in cardiac transplant recipients with pulmonary hypertension

2015 ESC/ERS Guidelines for the diagnosis and treatment of pulmonary hypertension

Guidelines summarize and evaluate all available evidence on a particular issue at the time of the writing process, with the aim of assisting health professionals in selecting the best management strategies for an individual patient with a given condition, taking into account the impact on outcome, as well as the risk–benefit ratio of particular diagnostic or therapeutic means. Guidelines and recommendations should help health professionals to make decisions in their daily practice. However, the final decisions concerning an individual patient must be made by the responsible health professional(s) in consultation with the patient and caregiver as appropriate.

Controversies in pulmonary hypertension due to left heart disease

Left heart failure is currently the most prevalent cause of pulmonary hypertension (PH) worldwide and this is due mainly to the increased left ventricular and pulmonary venous pressures seen in this condition. Still, a quota of patients with left heart failure will have a pulmonary arterial disease "disproportionate" to the initial increase of left-sided pressures. Whatever the mechanism involved, the appearance of PH is a powerful marker, as it determines decreased exercise tolerance and survival. To date, all trials using therapies approved for pulmonary arterial hypertension (PAH) failed to demonstrate a benefit in the context of heart failure (HF) without or with PH. In addition, the comparison among studies is limited by relevant differences in definitions, methodology, and timing of assessment. A novel rigorous hemodynamic classification based on the diastolic pulmonary gradient has been recently proposed to better characterize this form of PH. This will promote uniformity in patient populations and end-points for future clinical trials.

The diastolic pulmonary gradient does not predict survival in patients with pulmonary hypertension due to left heart disease

OBJECTIVES

This study sought to evaluate if diastolic pulmonary gradient (DPG) can predict survival in patients with pulmonary hypertension due to left heart disease (PH-LHD).

BACKGROUND

Patients with combined post- and pre-capillary PH-LHD have worse prognosis than those with passive pulmonary hypertension. The transpulmonary gradient (TPG) and pulmonary vascular resistance (PVR) have commonly been used to identify high-risk patients. However, these parameters have significant shortcomings and do not always correlate with pulmonary vasculature remodeling. Recently, it has been suggested that DPG may be better a marker, yet its prognostic ability in patients with cardiomyopathy has not been fully assessed.

METHODS

A retrospective cohort of 1,236 patients evaluated for unexplained cardiomyopathy at Johns Hopkins Hospital was studied. All patients underwent right heart catheterization and were followed until death, cardiac transplantation, or the end of the study period (mean time 4.4 years). The relationships between DPG, TPG, or PVR and survival in subjects with PH-LHD (n = 469) were evaluated with Cox proportional hazards regression and Kaplan-Meier analyses.

RESULTS

DPG was not significantly associated with mortality (hazard ratio [HR]: 1.02, p = 0.10) in PH-LHD whereas elevated TPG and PVR predicted death (HR: 1.02, p = 0.046; and HR: 1.11, p = 0.002, respectively). Similarly, DPG did not differentiate survivors from non-survivors at any selected cut points including a DPG of 7 mm Hg.

CONCLUSIONS

In this retrospective study of patients with cardiomyopathy and PH-LHD, an elevated DPG was not associated with worse survival.

Pulmonary hypertension in heart failure with preserved ejection fraction

In heart failure with preserved ejection fraction (HFpEF), an entity that remains challenging and difficult to treat, the development of pulmonary hypertension (PH), via an increase in left atrial pressure, is the direct consequence of reduced relaxation and enhanced stiffness of the left ventricle and is now viewed as an important contributor to clinical worsening and increased mortality. PH becomes a relevant clinical phenotype in approximately 50% of patients with HFpEF and represents a true challenge in the clinical follow-up and management of these patients. Along with these epidemiologic insights, there has been increasing recognition of the pathophysiology of PH and its consequences on the right ventricle in patients with HFpEF. Novel and effective therapeutic interventions aimed at preventing and reversing PH are highly relevant in the attempt to modify the poor clinical trajectory and growing health care burden of HFpEF. Many theoretical rationales as well as progressively accumulating evidence support the usefulness of nitric oxide pathway-potentiating compounds in targeting the lung vasculature through phosphodiesterase 5 inhibitors or guanylate cyclase stimulators to produce vasodilation and potentially a biologic effect. These pharmacologic strategies may be clinically effective options for the treatment of PH in patients with HFpEF; however, large controlled trials are necessary to address definitively the safety, tolerability, and potential impact on morbidity and mortality. This review details the pathophysiologic process, prevalence, and consequences of HFpEF-associated PH and discusses current and emerging treatment strategies to prevent or treat this deleterious sequela when present.

Pathophysiology and clinical relevance of pulmonary remodelling in pulmonary hypertension due to left heart diseases

Pulmonary hypertension (PH) in left heart disease, classified as group II, is the most common form of PH that occurs in approximately 60% of cases of reduced and preserved left ventricular ejection fraction. Although relatively much is known about hemodynamic stages (passive or reactive) and their consequences on the right ventricle (RV) there is no consensus on the best hemodynamic definition of group II PH. In addition, the main pathways that lead to lung capillary injury and impaired biology of small artery remodelling processes are largely unknown. Typical lung manifestations of an increased pulmonary pressure and progressive RV-pulmonary circulation uncoupling are an abnormal alveolar capillary gas diffusion, impaired lung mechanics (restriction), and exercise ventilation inefficiency. Of several classes of pulmonary vasodilators currently clinically available, oral phosphodiesterase 5 inhibition, because of its strong selectivity for targeting the cyclic guanosine monophosphate pathway in the pulmonary circulation, is increasingly emerging as an attractive opportunity to reach hemodynamic benefits, reverse capillary injury, and RV remodelling, and improve functional capacity. Guanylate cyclase stimulators offer an additional intriguing opportunity but the lack of selectivity and systemic effects might preclude some of the anticipated benefits on the pulmonary circulation. Future trials will determine whether new routes of pharmacologic strategy aimed at targeting lung structural and vascular remodelling might affect morbidity and mortality in left heart disease populations. We believe that this therapeutic goal rather than a pure hemodynamic effect might ultimately emerge as an important challenge for the clinician.