Background: The role of left atrial (LA) function on exercise remains poorly understood in heart failure with preserved ejection fraction (HfpEF) despite its key role in optimizing left ventricular (LV) diastolic function. We used resting and exercise radionuclide ventriculography to investigate the role of LA function in the pathophysiology of HfpEF.
Methods and results: A total of 25 patients with HfpEF and 15 age- and gender-matched controls were recruited. All subjects underwent resting echocardiogram, metabolic exercise testing to peak effort, and radionuclide ventriculography (at rest and exercise [to 35% of heart rate reserve]). At rest LA and LV function were similar in patients and controls. During exercise, HfpEF patients had lower left ventricular ejection fraction (69 +/- 9% vs. 73 +/- 10%, P < .05) and lower peak early filling rate (387 +/- 109 end-diastolic count/sec vs. 561 +/- 156 end-diastolic count/sec, P < .001). During exercise, the atrial contribution to LV filling was significantly higher in patients than controls (46 +/- 11% vs. 30 +/- 9%, P < .001). Atrial contribution to LV filling correlated negatively with peak early filling rate during exercise (r = -0.6, P < .001). Peak early filling rate correlated positively with peak oxygen consumption (r = 0.485, P = .004) and negatively with minute/carbon dioxide production (r = -0.423, P = .013).
Conclusion: Patients with HfpEF have increased atrial contribution to LV filling as a compensatory response to impaired early LV filling during cycle exercise.