Ten years ago, an Austrian group proposed implanting dual chamber pacemakers in advanced heart failure patients who did not meet the usual criteria for a pacing indication.1 Short term results were encouraging. A revolutionary idea was born: using cardiac pacing as an adjuvant therapy to medical treatment in drug refractory heart failure.

Meanwhile, however, pharmacological treatment made considerable progress. Angiotensin converting enzyme (ACE) inhibitors, β blockers, and spironolactone have significantly reduced mortality and morbidity in New York Heart Association (NYHA) class II–IV patients, while improving their quality of life.2-4 But that benefit is probably not permanent and will be limited in time. A variety of non-pharmacological approaches are available to treat these refractory heart failure patients. Heart transplant remains the best solution but it can only be applied to a restricted number of patients. So, for more than 10 years now, permanent dual chamber pacing with short atrioventricular delay has been proposed as an adjuvant treatment of advanced heart failure; however, the initially encouraging results were not proved in a long term follow up during prospective studies.5 ,6 One of the main causes for the failure of standard dual chamber pacing is probably that in patients with chronic left ventricular (LV) dysfunction, although it corrects, at least partially, atrioventricular asynchrony of the left heart, it also enhances the electromechanical consequences of intraventricular conduction delay which are often found in this type of patient.

Indeed, prolonged PR interval and wide QRS are frequently observed in patients with chronic heart failure associated with LV systolic dysfunction. Wilensky and colleagues thus demonstrated that atrioventricular and intraventricular conduction disorders, with 30% mean increase in PR interval and QRS duration, had been gradually occurring in more than …