title: Biphasic Force-Frequency Relation Predicts Primary Cardiac Events in Patients With Hypertrophic Cardiomyopathy.
abstract: The force-frequency relation (FFR) is a hemodynamic index of the chronotropic relationship between left ventricular (LV) systolic function (percent change in dP/dtmax) and elevation of heart rate. FFR is a marker of myocardial contractile reserve and follows an upward slope in healthy myocardium [monophasic FFR (MoF)], a pattern that becomes biphasic (BiF) under pathological conditions. However, it remains uncertain whether the FFR determines a patient's prognosis. We investigated the promising role of the FFR as a predictor of cardiac events in the setting of hypertrophic cardiomyopathy (HCM).
  
  
  
  A total of 113 consecutive patients with HCM (New York Heart Association (NYHA) class I-II) were retrospectively evaluated; 27 (23.9%) had a BiF pattern and they experienced a higher incidence of cardiac events compared with those showing an MoF pattern (median follow-up, 4.7 years; P<0.001). Furthermore, Cox proportional hazard regression analysis revealed that the LV end-diastolic volume index (hazard ratio: 1.051, P=0.014) and BiF pattern (hazard ratio: 15.260, P=0.001) were independent predictors of primary cardiac events. Interestingly, abnormal reductions in myocardial regulatory molecules related to contractility (SERCA2α) were observed exclusively in the patients exhibiting a BiF pattern.
  
  
  
  The FFR reflects latent myocardial abnormalities and predicts cardiac events in the setting of HCM, even during the asymptomatic stages of the disease.
authors.affiliation: Department of Cardiology, Nagoya University Graduate School of Medicine.
authors.forename: Ryota
authors.initials: R
authors.lastname: Morimoto
authors.forename: Takahiro
authors.initials: T
authors.lastname: Okumura
authors.forename: Yasuko K
authors.initials: YK
authors.lastname: Bando
authors.forename: Kenji
authors.initials: K
authors.lastname: Fukaya
authors.forename: Akinori
authors.initials: A
authors.lastname: Sawamura
authors.forename: Haruya
authors.initials: H
authors.lastname: Kawase
authors.forename: Shinya
authors.initials: S
authors.lastname: Shimizu
authors.forename: Shuzo
authors.initials: S
authors.lastname: Shimazu
authors.forename: Akihiro
authors.initials: A
authors.lastname: Hirashiki
authors.forename: Kyosuke
authors.initials: K
authors.lastname: Takeshita
authors.forename: Toyoaki
authors.initials: T
authors.lastname: Murohara
mesh_terms: D000368:Aged; D002312:Cardiomyopathy, Hypertrophic / Q000503:physiopathology*; D005500:Follow-Up Studies; D006339:Heart Rate; D006801:Humans; D008875:Middle Aged; D009200:Myocardial Contraction; D012189:Retrospective Studies; D016277:Ventricular Function, Left