title: New York Heart Association functional class, QRS duration, and survival in heart failure with reduced ejection fraction: implications for cardiac resychronization therapy.
abstract: Symptom severity assessed by NYHA functional class and QRS duration are essential criteria for selection of heart failure (HF) patients for CRT. This study assessed the relationship between NYHA class, QRS duration, and survival in a nationwide HF registry.
  
  
  
  We studied 13 423 patients with HF in NYHA class II-IV and LVEF <40% in the Swedish Heart Failure Registry. Survival was followed via the Swedish Population Registry. Of 12 534 patients without CRT (age 71 ± 12 years, 29% women), 51% and 49% were in NYHA class II and III-IV, respectively. Patients in NYHA class II compared with class III-IV were younger (69 vs. 73 years), and had a better systolic function (49% vs. 58% with LVEF <30%), P <0.001 for all, and a favourable co-morbidity profile. QRS duration was 116 ± 29 ms in NYHA class II and 119 ± 29 ms in NYHA class III-IV with QRS ≥120 ms found in 37% vs. 44%, and an LBBB in 23% vs. 28% (P < 0.001 for all). Upon multivariable Cox regression adjusting for 40 clinically relevant variables, mortality risk was higher in NYHA class III-IV vs. class II, with a hazard ratio (HR) of 1.31, 95% confidence interval (CI) 1.23-1.40. Mortality was also higher with QRS prolongation ≥120 ms vs. narrow QRS. The HR in NYHA class II patients with non-LBBB was 1.19 (95% CI 1.05 - 1.36) and in those with LBBB it was 1.16 (95% CI 1.03-1.41). The corresponding HRs in NYHA class III-IV were 1.33 (95% CI 1.21-1.47) and 1.12 (95% CI 1.02-1.22). There was no significant interaction between the effects of NYHA class and QRS duration or morphology on mortality. Applying different scenarios to estimate guideline adherence, fewer patients with NYHA class II (range 14.4-42.6%) compared with NYHA class III-IV (18.0-45.4%) had received a CRT device when indicated.
  
  
  
  In HF with reduced LVEF, QRS prolongation is common and independently linked to worse survival. The increase in mortality risk associated with QRS prolongation of both LBBB and non-LBBB morphology is similar in NYHA class II and III-IV.
authors.affiliation: Karolinska Institutet, Department of Medicine, Stockholm, Sweden.|Karolinska University Hospital, Department of Cardiology, Stockholm, Sweden.
authors.forename: Frieder
authors.initials: F
authors.lastname: Braunschweig
authors.affiliation: Karolinska Institutet, Department of Medicine, Stockholm, Sweden.|Karolinska University Hospital, Department of Cardiology, Stockholm, Sweden.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Linde
authors.affiliation: Karolinska Institutet, Department of Clinical Science and Education, South Hospital, Stockholm, Sweden.
authors.forename: Lina
authors.initials: L
authors.lastname: Benson
authors.affiliation: Karolinska Institutet, Department of Medicine, Stockholm, Sweden.|Karolinska University Hospital, Department of Cardiology, Stockholm, Sweden.
authors.forename: Marcus
authors.initials: M
authors.lastname: Ståhlberg
authors.affiliation: Department of Cardiology and Department of Medicine and Health Sciences, Linköping University, Linköping, Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Dahlström
authors.affiliation: Karolinska Institutet, Department of Medicine, Stockholm, Sweden.|Karolinska University Hospital, Department of Cardiology, Stockholm, Sweden.
authors.forename: Lars H
authors.initials: LH
authors.lastname: Lund
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002037:Bundle-Branch Block / Q000150:complications / Q000503:physiopathology* / Q000628:therapy; D058406:Cardiac Resynchronization Therapy / Q000706:statistics & numerical data; D004562:Electrocardiography; D005260:Female; D019983:Guideline Adherence; D006333:Heart Failure / Q000150:complications / Q000401:mortality / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D017410:Practice Guidelines as Topic; D016016:Proportional Hazards Models; D012042:Registries; D012720:Severity of Illness Index; D013318:Stroke Volume; D015996:Survival Rate; D013548:Sweden
keywords: Cardiac resynchronization therapy; Epidemiology; Heart failure; Left bundle branch block; NYHA functional class; QRS width