Defining the Phenotypes for Pulmonary Hypertension Associated With Diastolic Heart Failure

Abstract

Pulmonary hypertension (PH) is well known to be associated with left heart failure, which is probably the single most common cause of abnormally elevated pulmonary arterial pressure (>25 mm Hg by consensus).1–3 Estimates range up to 250 000 patients with PH associated with heart failure in the United States today,3,4 making it far more prevalent than other forms of PH. Consistent with this, more than three-quarters of unselected patients referred for cardiac ultrasound to a single community-based center and found to have an elevated estimated pulmonary arterial (PA) systolic pressure were subsequently determined to have a left ventricular (LV) cause.5 Despite its prevalence, though, the pathophysiology and phenotypic characteristics of PH associated with left heart failure are not well understood. Article see p 257 By expert consensus, the World Health Organization has classified PH into 5 groups, based partly on pathophysiologic and hemodynamic characteristics.6 Group 1, referred to as pulmonary arterial hypertension (PAH), includes idiopathic and hereditary varieties as well as PAH associated with connective tissue disease, congenital heart disease, portal hypertension, HIV, and others. PH owing to elevated left heart filling pressure is classified as group 2 (pulmonary venous hypertension), including PH attributable to LV systolic dysfunction, LV diastolic dysfunction, and valvular disease. Some prefer the term “heart failure with a preserved LV ejection fraction” (HFpEF) over “diastolic” heart failure because not all such patients necessarily have evidence of diastolic dysfunction,7 but the terms are often used interchangeably. An elevation in mean PA pressure is expected when LV filling pressure increases because this is necessary to maintain blood flow. Most of the time, the increase is “proportionate” or “passive”—enough to maintain the transpulmonary gradient (TPG), the pressure difference between mean PA pressure and the pulmonary capillary wedge pressure (PCWP). However, …