[Pacemaker stimulation in dilated and hypertrophic myocardiopathies: should its use be stratified?]

New indications for permanent cardiac pacing have been developed in recent years, with numerous studies demonstrating improved clinical outcomes in many disorders. These techniques have been used in hypertrophic obstructive cardiomyopathy and dilated cardiomyopathy, and many physiological bases and clinical studies justify their application. In dilated cardiomyopathy and heart failure with intraventricular conduction delay, abnormal electrical depolarization of the heart results in mechanical asynchrony of the ventricles. Tricameral pacing (atrial-based biventricular) offers an alternative and conditions ventricular synchronization. The MUSTIC study, a controlled, randomized, crossover study, showed promising results, significantly improving exercise tolerance and quality of life, and increasing in diastolic ventricular filling period. Several ongoing randomized, controlled clinical trials should provide more definitive data on safety, efficacy, and decreased mortality. Hypertrophic obstructive cardiomyopathy has many therapeutic approaches such as, medical treatment, dual chamber pacing, surgery, and transcatheter septal ablation. Dual chamber pacing has been shown to improve symptoms and hemodynamic variables in patients severely symptomatic. However, randomized clinical trials (PIC and M-PATHY) have not shown conclusive evidence regarding the long-term benefit from pacing in these patients. Moreover, relationship between reduction in the intraventricular gradient and improvement of symptoms is controversial; there might be a significant placebo effect. Cardiac pacing is an alternative therapy for selected patients with hypertrophic cardiomyopathy, but very careful screening of patients is mandatory.