Background:
The diagnosis of heart failure with preserved ejection fraction (HFpEF) remains challenging. Recently, the HFpEF Stress Trial demonstrated feasibility and accuracy of non-invasive cardiovascular magnetic resonance (CMR) real-time exercise-stress atrial function imaging for early identification of HFpEF. However, no outcome data has yet been presented.

Methods:
The HFpEF Stress Trial (DZHK-17) prospectively recruited 75 patients with dyspnea on exertion and echocardiographic preserved EF and signs of diastolic dysfunction (E/e’>8). 68 patients entered the final study cohort and were characterized as HFpEF (n=34) or non-cardiac dyspnea (n=34) according to pulmonary capillary wedge pressure (HFpEF: PCWP rest: ≥15mmHg stress: ≥25mmHg). These patients were contacted by telephone and hospital charts were reviewed. Clinical endpoints included cardiovascular hospitalisation and mortality.

Results:
Follow-up was performed after 24 months; 2 patients were lost to follow-up. HFpEF patients were numerically more often hospitalized compared to non-cardiac dyspnea but not reaching statistical significance (8 vs. 3, p=0.123). There were no cardiovascular deaths. Hospitalised patients during follow-up had higher H2FPEF scores (5 vs. 3, p=0.004), and impaired left atrial (LA) function at rest (p≤0.006) and stress (p≤0.009). Impairment of CMR-derived atrial function parameters at rest and during exercise-stress (p≤0.009) was associated with increased likelihood for cardiovascular hospitalisation, independently of the presence of atrial fibrillation (p<0.05 for all). LA reservoir function at rest showed the highest diagnostic accuracy (AUC 0.87) and yielded significant incremental prognostic value compared to clinical biomarkers (NTproBNP), echocardiographic imaging (E/e’) and invasive RHC (PCWP) parameters.

Conclusions:
Left atrial peak reservoir strain at rest emerged as the strongest predictor for medium-term outcome in the HFpEF Stress Trial. A combination of rest and exercise-stress CMR imaging may allow more accurate diagnostic and prognostic stratification in HFpEF.