Left Heart Disease-Related Pulmonary Hypertension

Group 2 pulmonary hypertension: from diagnosis to treatment

PURPOSE OF REVIEW

Pulmonary hypertension associated with left heart disease (PHLHD) is common and associated with adverse prognosis. Proper diagnosis is critical to avoid inappropriate treatment. Practical approaches to noninvasive diagnosis are available, though invasive hemodynamics including volume loading or exercise are often necessary for definitive diagnosis. Treatment strategies and research in the field is rapidly evolving.

RECENT FINDINGS

Combined pre and post capillary pulmonary hypertension is associated with remodeling of the pulmonary vasculature that is proportional to the severity of the pulmonary hypertension. Even quite mild elevation of pulmonary vascular resistance (PVR), (greater than 2.0 Wood units (WU)) is associated with adverse outcome. Guideline-directed medical therapy (GDMT) for left heart failure has rapidly evolved, including approval of SGLT2 inhibitors for treatment of heart failure with preserved ejection fraction (HFpEF). However, full implementation of GDMT is lagging. Utilization of implanted pulmonary artery pressure monitoring can facilitate patient management in selected patient phenotypes and has been utilized to demonstrate improvement in pulmonary pressures with emerging therapies in HFpEF including SGLT2 inhibitors and sacubitril/valsartan. A variety of shunt devices to create a left-to-right shunt in order to decompress the left heart are available or undergoing clinical trials. There is concern that there could be adverse response to such devices in patients who have even mild elevation of pulmonary vascular resistance. Sleep disordered breathing is common in PHLHD and should be aggressively sought out and treated.

SUMMARY

Even mild elevation in pulmonary vascular resistance is associated with adverse outcome. A systematic approach to diagnosis of PHLHD is essential. Guideline-directed medical therapy for PHLHD prioritizes optimal management of the left heart disease. Pulmonary artery pressure sensors are useful in selected patients.

Novel Drugs for the Treatment of Pulmonary Arterial Hypertension: Where Are We Going?

Pulmonary arterial hypertension (PAH) is a progressive disease that despite advances in therapy is associated with a 7-year survival of approximately 50%. Several risk factors are associated with developing PAH, include methamphetamine use, scleroderma, human immunodeficiency virus, portal hypertension, and genetic predisposition. PAH can also be idiopathic. There are traditional pathways underlying the pathophysiology of PAH involving nitric oxide, prostacyclin, thromboxane A2, and endothelin-1, resulting in impaired vasodilation, enhanced vasoconstriction and proliferation in the pulmonary vasculature. Established PAH medications targets these pathways; however, this paper aims to discuss novel drugs for treating PAH by targeting new and alternative pathways.

Therapeutic augmentation of NO-sGC-cGMP signalling: lessons learned from pulmonary arterial hypertension and heart failure

The nitric oxide (NO)-guanylate cyclase (GC)-cyclic guanosine monophosphate (cGMP) pathway plays an important role in cardiovascular, pulmonary and renal function. Phosphodiesterase-5 inhibitors (PDE-5i) inhibit cGMP degradation, whereas both soluble guanylate cyclase (sGC) stimulators and sGC activators directly increase sGC. PDE-5i (e.g. sildenafil, tadalafil) and sGC stimulators (e.g. riociguat, vericiguat) have been extensively used in pulmonary artery hypertension (PAH) and heart failure (HF). PDE-5i have also been used in end-stage HF before and after left ventricular (LV) assist device (LVAD) implantation. Augmentation of NO-GC-cGMP signalling with PDE-5i causes selective pulmonary vasodilation, which is highly effective in PAH but may have controversial, potentially adverse effects in HF, including pre-LVAD implant due to device unmasking of PDE-5i-induced RV dysfunction. In contrast, retrospective analyses have demonstrated that PDE-5i have beneficial effects when initiated post LVAD implant due to the improved haemodynamics of the supported LV and the pleiotropic actions of these compounds. sGC stimulators, in turn, are effective both in PAH and in HF due to their balanced pulmonary and systemic vasodilation, and as such they are preferable to PDE-5i if the use of a pulmonary vasodilator is needed in HF patients, including those listed for LVAD implantation. Regarding the effectiveness of PDE-5i and sGC stimulators when initiated post LVAD implant, these two groups of compounds should be tested in a randomized control trial.