SHort Of Pace - Heart Failure (SHOP-HF)

This study is designed as a multicenter, prospective, controlled, randomized, two-arms, cross-over, two parallel cohorts, efficacy Clinical research with CE-marked medical device . The crossover trial will be performed in a blind fashion, so each participant will be evaluated during both blinded pacing-on and pacing-off phases, each of which will last 3 months. The population includes patients with the diagnosis of stable HFpEF according to criteria of the European Society of Cardiology and New York Heart Association (NYHA) functional class II-III/IV, left ventricular hypertrophy with small ventricular volume, sinus rhythm with low basal heart rate and chronotropic incompetence (CI). All patients will undergo pacemaker implantation, and computer-generated randomization sequence previously designed will be used to allocate participants (in a 1:1 ratio) to receive: (a) programming of the pacemaker with pacing On followed by pacing Off in two periods of 3 months; or (b) programming of the pacemaker with pacing Off followed by pacing On in two periods of 3 months. The study will be conducted in three centers in Spain. Discounting the time due to staggered entry, the total duration of a patient's follow-up will be 7 months.