title: Sustained sympathoinhibitory effects of cardiac resynchronization therapy in severe heart failure.
abstract: Evidence is available that in heart failure, cardiac resynchronization therapy by biventricular pacing improves myocardial function and exercise capacity. Whether this is accompanied by a sustained inhibition of heart failure-dependent sympathoexcitation is uncertain. In 11 heart failure patients (mean+/-SEM age, 68.4+/-1.5 years) in New York Heart Association (NYHA) class III and IV under medical treatment with an intraventricular conduction delay (QRS duration > or =130 ms), with a markedly depressed left ventricular ejection fraction, and undergoing implantation of a biventricular pacemaker, we measured beat-to-beat blood pressure and muscle sympathetic nerve traffic. Measurements, which also included echocardiographic and clinical variables, were performed before and approximately 10 weeks after successful resynchronization therapy. Ten age- and NYHA class-matched heart failure patients who were under medical treatment for the same time period served as controls. Long-term resynchronization therapy improved cardiac function and caused a significant increase in systolic blood pressure coupled with an improvement in maximal oxygen consumption and exercise capacity. These effects were coupled with a significant and marked reduction in sympathetic nerve traffic when expressed both as burst frequency over time (44.1+/-3.6 vs 30.7+/-3.0 bs/min, -30.5%, P<0.02) and as burst frequency corrected for heart rate (68.3+/-5.9 vs 47.3+/-4.3 bs/100 beats, -32.1%, P<0.02). No significant change in the aforementioned parameters was seen in the control group. These data provide the first direct evidence that in severe heart failure, resynchronization therapy exerts a marked and sustained sympathoinhibition. Because in heart failure sympathetic overactivity adversely affects prognosis, this may have important clinical implications.
authors.affiliation: Clinica Medica, Dipartimento di Medicina Clinica, Prevenzione e Biotecnologie Sanitarie, Università Milano-Bicocca, Italy.
authors.forename: Guido
authors.initials: G
authors.lastname: Grassi
authors.forename: Antonio
authors.initials: A
authors.lastname: Vincenti
authors.forename: Roberta
authors.initials: R
authors.lastname: Brambilla
authors.forename: Fosca Quarti
authors.initials: FQ
authors.lastname: Trevano
authors.forename: Raffaella
authors.initials: R
authors.lastname: Dell'Oro
authors.forename: Antonio
authors.initials: A
authors.lastname: Cirò
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Trocino
authors.forename: Antonella
authors.initials: A
authors.lastname: Vincenzi
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Mancia
mesh_terms: D000368:Aged; D002304:Cardiac Pacing, Artificial; D006333:Heart Failure / Q000503:physiopathology* / Q000628:therapy*; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D013564:Sympathetic Nervous System / Q000502:physiology*