title: Prognostic indices among hypertensive heart failure patients in Nigeria: the roles of 24-hour Holter electrocardiography and 6-minute walk test.
abstract: BACKGROUND
  Hypertensive heart failure (HHF) is associated with a poor prognosis. There is paucity of data in Nigeria on prognosis among HHF patients elucidating the role of 24-hour Holter electrocardiogram (ECG) in concert with other risk factors.
  
  
  OBJECTIVE
  The aim of this study was to determine the prognostic utility of 24-hour Holter ECG, the 6-minute walk test (6-MWT), echocardiography, clinical and laboratory parameters among HHF patients.
  
  
  METHODS
  A total of 113 HHF patients were recruited and followed up for 6 months. Thirteen of these patients were lost to follow-up, and as a result only 100 HHF patients were analyzed. All the patients underwent baseline laboratory tests, echocardiography, 24-hour Holter ECG and the 6-MWT. HHF patients were analyzed as "mortality vs alive" and as "events vs no-events" based on the outcome at the end of 6 months. Events was defined as HHF patients who were rehospitalized for heart failure (HF), had prolonged hospital stay or died. No-events group was defined as HHF patients who did not meet the criteria for the events group.
  
  
  RESULTS
  HHF patients in the mortality group (n = 7) had significantly higher serum urea (5.71 ± 2.07 mmol/L vs 3.93 ± 1.45 mmol/L,p= 0.003) than that in those alive. After logistic regression, high serum urea conferred increased mortality risk (p= 0.035). Significant premature ventricular complexes (PVCs) on 24-hour Holter ECG following logistic regression were also significantly higher (p= 0.015) in the mortality group than in the "alive" group (n = 93) at the end of the 6-month follow-up period. The 6-minute walk distance (6-MWD) was least among the HHF patients who died (167.26 m ± 85.24 m). However, following logistic regression, the 6-MWT was not significant (p= 0.777) for predicting adverse outcomes among HHF patients. Patients in the events group (n = 41) had significantly higher New York Heart Association (NYHA) class (p= 0.001), Holter-detected ventricular tachycardia (VT;p= 0.009), Holter-detected atrial fibrillation (AF;p= 0.028) and PVCs (p= 0.017) following logistic regression than those in the no-events group (n = 59).
  
  
  CONCLUSIONS
  High NYHA class, elevated serum urea, Holter ECG-detected AF and ventricular arrhythmias are predictive of a poor outcome among HHF patients. The 6-MWT was not a useful prognostic index in this study.
authors.affiliation: Department of Medicine, Metropolitan Hospital Center, New York, NY, USA; Cardiology Unit, Department of Medicine, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Osun State, Nigeria.
authors.forename: Tuoyo O
authors.initials: TO
authors.lastname: Mene-Afejuku
authors.affiliation: Cardiology Unit, Department of Medicine, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Osun State, Nigeria.
authors.forename: Michael O
authors.initials: MO
authors.lastname: Balogun
authors.affiliation: Cardiology Unit, Department of Medicine, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Osun State, Nigeria.
authors.forename: Anthony O
authors.initials: AO
authors.lastname: Akintomide
authors.affiliation: Cardiology Unit, Department of Medicine, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Osun State, Nigeria.
authors.forename: Rasaaq A
authors.initials: RA
authors.lastname: Adebayo
mesh_terms: D000368:Aged; D001281:Atrial Fibrillation / Q000175:diagnosis* / Q000209:etiology / Q000401:mortality / Q000503:physiopathology; D015415:Biomarkers / Q000097:blood; D016009:Chi-Square Distribution; D015150:Echocardiography, Doppler; D015716:Electrocardiography, Ambulatory; D017079:Exercise Tolerance; D005260:Female; D006304:Health Status; D006333:Heart Failure / Q000175:diagnosis* / Q000209:etiology / Q000401:mortality / Q000503:physiopathology; D006339:Heart Rate; D006801:Humans; D006973:Hypertension / Q000150:complications* / Q000175:diagnosis / Q000401:mortality / Q000503:physiopathology; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009549:Nigeria; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D015203:Reproducibility of Results; D012307:Risk Factors; D017180:Tachycardia, Ventricular / Q000175:diagnosis* / Q000209:etiology / Q000401:mortality / Q000503:physiopathology; D013997:Time Factors; D015854:Up-Regulation; D014508:Urea / Q000097:blood; D018879:Ventricular Premature Complexes / Q000175:diagnosis* / Q000209:etiology / Q000401:mortality / Q000503:physiopathology; D000070857:Walk Test
chemical_list: D015415:Biomarkers; D014508:Urea
keywords: Holter electrocardiography; hypertensive heart failure; prognosis; ventricular tachycardia