Cardiac Dysfunction, Exercise Reserve, and Outcomes in Patients With Heart Failure With Preserved Ejection Fraction...

Patients with heart failure with preserved ejection fraction (HFpEF) and a pacemaker have been shown to have an increased risk for adverse events and may respond differently to novel treatments such as atrial shunt devices. Whether there are pathophysiological differences in patients with HFpEF and a pacemaker is unknown.

Individuals with HFpEF with and without a pacemaker and noncardiac dyspnea underwent invasive hemodynamic exercise testing with simultaneous expired gas analysis for the evaluation of unexplained dyspnea. HFpEF with a pacemaker (HFpEF_PM; n = 67) displayed more severe left and right ventricular dysfunction and more severe biatrial myopathy and significant tricuspid regurgitation as compared with HFpEF without a pacemaker (n = 507) and noncardiac dyspnea (n = 178). On exercise, patients with HFpEF_PM displayed more chronotropic incompetence and impaired ability to augment stroke volume with exercise. The increase in cardiac output relative to increases in central venous pressure was diminished in those with HFpEF_PM, in comparison with individuals with HFpEF without a pacemaker or noncardiac dyspnea. Over a median of 3.0 years of follow-up (interquartile range, 1.2-5.1 years of follow-up), 116 patients (15.4%) experienced the composite of HF hospitalization or death. Patients with HFpEF_PM displayed higher risk of the composite events as compared with other groups (log-rank P < 0.0001).

Prior pacemaker implantation in HFpEF is associated with more severe biventricular and biatrial dysfunction, impaired exercise capacity, and worse outcomes compared with those with no pacemaker. Further study is required to determine to what extent these differences are causally related to pacemakers or are confounding patient-specific differences associated with the need for pacemaker implantation.