title: Impact of myocardial viability assessed by myocardial perfusion imaging on ventricular tachyarrhythmias in cardiac resynchronization therapy.
abstract: BACKGROUND
  The presence of myocardial fibrosis is associated with ventricular tachyarrhythmia (VT) occurrence irrespective of cardiomyopathy etiology. The aim of our study was to evaluate the impact of global and regional viability on VTs in patients undergoing cardiac resynchronization therapy (CRT).
  
  
  METHODS
  Fifty-seven patients with advanced heart failure (age 62.3 ± 10.2; 38 men; 24 ischemic etiology) were evaluated using single-photon emission computed tomography myocardial perfusion imaging before CRT defibrillator device implantation. Global myocardial viability was determined by the number of viable segments in a 20-segment model. Regional viability was calculated as the mean tracer activity in the corresponding segments at left ventricular (LV) lead position. LV lead segments were determined at implant venography using 2 projections (left anterior oblique 30 and right anterior oblique 30) of coronary sinus tributaries. Patients were followed 30 (24-34) months for the occurrence of VTs.
  
  
  RESULTS
  VTs were registered in 18 patients (31.6%). Patients without VTs had significantly more viable segments (17.6 ± 2.35 vs 14.2 ± 4.0; P = .002) and higher regional myocardial viability at LV lead position (66.1% ± 10.3% vs 54.8% ± 11.4% of tracer activity; P = .001) than those with VTs. In multivariate logistic regression models, the number of viable segments (OR = 0.66; 95% confidence interval (CI) 0.53-0.85; P = .001) and regional viability (OR = 0.90; 95% CI 0.85-0.97; P = .003) were the only independent predictors of VT occurrence.
  
  
  CONCLUSIONS
  Global and regional myocardial viability are independently related to the occurrence of VTs in patients after CRT.
authors.affiliation: Department of Cardiology, University Medical Centre Ljubljana, Zaloška 7, 1000, Ljubljana, Slovenia, davidzizek@yahoo.com.
authors.forename: David
authors.initials: D
authors.lastname: Žižek
authors.forename: Marta
authors.initials: M
authors.lastname: Cvijić
authors.forename: Luka
authors.initials: L
authors.lastname: Ležaić
authors.forename: Barbara Gužič
authors.initials: BG
authors.lastname: Salobir
authors.forename: Igor
authors.initials: I
authors.lastname: Zupan
mesh_terms: D000368:Aged; D058406:Cardiac Resynchronization Therapy; D004452:Echocardiography; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D011446:Prospective Studies; D017180:Tachycardia, Ventricular / Q000000981:diagnostic imaging* / Q000209:etiology; D015899:Tomography, Emission-Computed, Single-Photon / Q000379:methods*