title: DDD pacing in hypertrophic cardiomyopathy: a multicentre clinical experience.
abstract: BACKGROUND
  DDD pacing has been advocated as an effective treatment for drug refractory obstructive hypertrophic cardiomyopathy. This study reports the outcome of pacing in 56 patients with refractory symptoms referred to four tertiary centres.
  
  
  METHODS
  Core data on symptoms, drug burden, and left ventricular outflow tract gradient were recorded. Patients underwent a temporary pacing study with optimisation of the atrioventricular (AV) delay for greatest gradient reduction without haemodynamic compromise. Patients were assessed after implantation in terms of changes in symptoms, drug load, and outflow tract gradient.
  
  
  RESULTS
  56 patients underwent pacing assessment. The mean (SD) left ventricular outflow tract gradient before pacing was 78 (31) mm Hg. At temporary study the mean (SD) left ventricular outflow tract gradient was 38 (24) mm Hg with a median (range) optimised sensed AV delay of 65 (25-125) ms. Fifty three patients were implanted and followed up for a mean (SD) of 11 (11) months. The median (range) programmed sensed AV delay was 60 (31-200) ms. Left ventricular outflow tract gradient at follow up was 36 (25) mm Hg. Forty four patients had improved functional class. Although a correlation (r = 0.69) was shown between acute and chronic left ventricular outflow tract gradient reduction, there was no correlation between magnitude of gradient reduction and functional improvement, and no appreciable change in pharmacological burden.
  
  
  CONCLUSIONS
  This series confirms symptomatic improvement after DDD pacing in hypertrophic cardiomyopathy. There remains, however, a discrepancy between perceived symptomatic benefit and modest objective improvement. Furthermore, the optimal outcome has been achieved only with continued pharmacological treatment. Current methods of temporary evaluation do not predict functional outcome which seems to be independent of the magnitude of gradient reduction.
authors.affiliation: Department of Cardiological Sciences, St George's Hospital Medical School, London.
authors.forename: A K
authors.initials: AK
authors.lastname: Slade
authors.forename: N
authors.initials: N
authors.lastname: Sadoul
authors.forename: L
authors.initials: L
authors.lastname: Shapiro
authors.forename: L
authors.initials: L
authors.lastname: Chojnowska
authors.forename: J P
authors.initials: JP
authors.lastname: Simon
authors.forename: R C
authors.initials: RC
authors.lastname: Saumarez
authors.forename: B
authors.initials: B
authors.lastname: Dodinot
authors.forename: A J
authors.initials: AJ
authors.lastname: Camm
authors.forename: W J
authors.initials: WJ
authors.lastname: McKenna
authors.forename: E
authors.initials: E
authors.lastname: Aliot
mesh_terms: D000293:Adolescent; D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D000328:Adult; D000368:Aged; D002121:Calcium Channel Blockers / Q000627:therapeutic use; D002304:Cardiac Pacing, Artificial; D002312:Cardiomyopathy, Hypertrophic / Q000188:drug therapy / Q000628:therapy*; D003131:Combined Modality Therapy; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D010138:Pacemaker, Artificial; D016896:Treatment Outcome
chemical_list: D000319:Adrenergic beta-Antagonists; D002121:Calcium Channel Blockers