There is no evidence-based treatment for heart failure with preserved ejection fraction. Although lower heart rates (HRs) provide an unequivocal benefit for patients with HF with reduced ejection fraction, higher HR might convey important hemodynamic and substrate-modifying benefits in patients with diastolic dysfunction. In a prospective study of 20 stable outpatients with diastolic dysfunction and pacemakers, we evaluated the effects of a 4-week increase in the lower pacemaker rate to 80 beats/min followed by reversal to the previous lower HR setting from weeks 4 to 6. We assessed quality of life (Minnesota Living with Heart Failure Questionnaire), 6-minute walk test and N-terminal pro-brain natriuretic peptide (NT-proBNP) levels. Pacing at 80 beats/min significantly improved quality of life and the 6-minute walk test (p ≤0.05). There was a strong positive correlation between the pacing-induced changes in NT-proBNP and baseline QRS intervals (r² = 0.31, p <0.01). Stratification by QRS duration revealed that pacing at 80 beats/min led to −21 ± 26% reduction in NT-proBNP in patients with QRS ≤150 ms, whereas QRS >150 ms was associated with a 26 ± 35% increase in NT-proBNP (p <0.01). Patients physiologically paced from the conduction system had a −46 ± 26% reduction in NT-proBNP at 80 beats/min as compared with 4 ± 26% and 13 ± 26% change with pacing from the right atrial appendage and right ventricular apical septum (p_interaction = 0.04). In conclusion, increasing the lower rate setting of pacemakers to 80 beats/min in patients with diastolic dysfunction improves quality of life, functional capacity, and NT-proBNP for those patients with a baseline QRS ≤150 ms. These findings suggest that higher HRs may provide meaningful benefits to patients with left ventricular diastolic dysfunction and heart failure with preserved ejection fraction.