title: The natural course of untreated sick sinus syndrome and identification of the variables predictive of unfavorable outcome.
abstract: We performed a prospective study in 35 untreated patients aged > or = 45 years, who had a mean sinus rate at rest of < or = 50 beats/min and/or intermittent sinoatrial block, and symptoms attributable to sinus node dysfunction. The patients were followed up for up to 4 years (mean 17 +/- 15 months). During follow-up, 20 patients (57%) had cardiovascular events that required treatment: 8 had syncope (23%); 6 had overt heart failure (17%); 4 patients had chronic atrial fibrillation (11%); and 2 patients had poorly tolerated episodes of paroxysmal tachyarrhythmias (6%). Actuarial rates of occurrence of all events were 35%, 49%, and 63%, respectively, after 1, 2, and 4 years. At univariate analysis, age > or = 65 years, end-systolic left ventricular diameter > or = 30 mm, end-diastolic left ventricular diameter > or = 52 mm, and ejection fraction < 55% were predictors of cardiovascular events. At multivariate analysis, age, end-diastolic diameter, and ejection fraction remained independent predictors of events. Actuarial rates of occurrence of syncope were 16%, 31%, and 31%, respectively, after 1, 2, and 4 years. Both univariate and multivariate predictors of syncope were history of syncope and corrected sinus node recovery > or = 800 ms. A favorable outcome was observed in the remaining 43% of patients. Thus, clinical cardiovascular events occur in most untreated sick sinus syndrome patients during long-term follow-up, even though a favorable course can be expected in 43% of patients. The outcome can be partly predicted on initial evaluation. In the patients with a favorable outcome, treatment can safely be delayed.
authors.affiliation: Arrhythmology Center, Department of Cardiology, Ospedale S Maria Nuova, Reggio Emilia, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Menozzi
authors.forename: M
authors.initials: M
authors.lastname: Brignole
authors.forename: P
authors.initials: P
authors.lastname: Alboni
authors.forename: L
authors.initials: L
authors.lastname: Boni
authors.forename: N
authors.initials: N
authors.lastname: Paparella
authors.forename: G
authors.initials: G
authors.lastname: Gaggioli
authors.forename: G
authors.initials: G
authors.lastname: Lolli
mesh_terms: D000206:Actuarial Analysis; D000368:Aged; D000704:Analysis of Variance; D001281:Atrial Fibrillation / Q000209:etiology; D018572:Disease-Free Survival; D004452:Echocardiography; D004562:Electrocardiography; D015716:Electrocardiography, Ambulatory; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012804:Sick Sinus Syndrome / Q000150:complications / Q000503:physiopathology*; D013575:Syncope / Q000209:etiology; D013610:Tachycardia / Q000209:etiology