Survival Estimates Limited by PH for Certain Heart Failure Patients: Study
Breathing problems are more common in patients with heart failure with reduced ejection fraction who also have pulmonary hypertension (PH) than in those who do not have PH, a study reported.
Patients with PH also had poorer lung function and long-term survival than those without PH. However, while spirometry can be used to estimate long-term survival in people without PH, it cannot make reliable estimates for patients with PH, regardless of how well their lungs are working, the research team noted. Spirometry, a measure of the amount of air moving in and out during a single breath, is a test of lung health.
“The presence of PH interacts with pulmonary function results and renders spirometric [lung function] indexes ineffective to provide prognostic information for long‐term outcomes in patients with heart failure with reduced ejection fraction,” the researchers wrote.
The study, “Prognostic role of pulmonary function in patients with heart failure with reduced ejection fraction,” was published in the Journal of the American Heart Association.
Ejection fraction is a measure of how well the heart pumps blood from the ventricles — the two chambers toward the bottom of the heart — out to the body. It is usually expressed as a percentage: a normal ejection fraction may be 50% to 75%, and a borderline ejection fraction 41% to 49%. An ejection fraction of 40% or less means the heart’s ability to pump blood out with each heartbeat is impaired.
A low ejection fraction can lead to high pressure within the left ventricle — the heart’s main pumping chamber — as the blood fills it between each heartbeat. In turn, this can result in breathing problems and PH, or a high pressure in the lungs’ blood vessels. An estimated 40% to 75% of patients with heart failure with reduced ejection fraction develop PH.
“Although it has been reported that the presence of PH may also affect the pulmonary function, the correlation between ventilatory abnormalities and the presence of PH attributable to left heart disease has [not] yet been well studied,” the researchers wrote.
To better determine if a correlation exists, the researchers drew on data from INHALER (INvestigate HeArt and Lung intERaction), a registry at a major medical center in Taiwan.
They included 440 patients (mean age, 66.2; 77% men) with an ejection fraction measured at the left ventricle of 40% or less. All patients underwent echocardiography — a procedure that uses ultrasound to look at how well the heart is pumping blood — and spirometry.
Of these 440 people, 158 (35.9%) patients had PH, as defined by a pressure against the pulmonary artery wall of 50 millimeters of mercury (mmHg) or more. The pulmonary artery is the large blood vessel carrying blood from the heart’s right ventricle to the lungs.
Compared with patients without PH, those with PH had significantly lower total lung capacity (78.3% vs. 83.8%), forced vital capacity (62.6% vs. 70.5%), and forced expiratory volume in the first second (63.9% vs. 72.4%). All three spirometry tests are measures of lung function.
During a median follow‐up of about two years (25.9 months), 111 of these people died. Compared with patients without PH, those with PH were at a higher risk of mortality (33.5% vs. 20.6%). Deaths due to cardiovascular causes were identified in 32 (55.2%) patients without PH and 34 (64.2%) with PH.
After accounting for several factors, total lung capacity, forced vital capacity, and forced expiratory volume in the first second all correlated with mortality for patients without PH. Impaired lung function linked with a 2.85 times higher risk of death for patients without PH, but not for those with PH.
“Pulmonary function provided prognostic information for long‐term survival in patients without PH, but not in patients with PH, regardless of their functional capacity. The study suggested that spirometric variables could be sensitive markers to reflect the cardiopulmonary interaction in HF [heart failure]; however, the significant prognostic information could only be limited to patients without PH,” the researchers wrote.
“Despite the fact that static spirometric measurement fails to be associated with long‐term outcomes in the presence of PH, whether exercise capacity is a more reliable prognostic factor requires more investigation,” they added.