title: Role of quantitative myocardial positron emission tomography for risk stratification in patients with hypertrophic cardiomyopathy: a 2016 reappraisal.
abstract: OBJECTIVE
  Myocardial blood flow <1.1 mL/min/g following dipyridamole (Dip-MBF) assessed by positron emission tomography (PET) was identified in 2003 as an important outcome predictor in hypertrophic cardiomyopathy (HCM), based on scans performed in the 90s. However, such extreme Dip-MBF impairment is rarely observed in contemporary cohorts. We, therefore, reassessed the Dip-MBF threshold defining high-risk HCM patients.
  
  
  METHODS
  Dip-MBF was measured using13N-ammonia in 100 HCM consecutive patients, prospectively enrolled and followed for 4.0 ± 2.2 years. Outcome was assessed based on tertiles of Dip-MBF. The study end-point was a combination of cardiovascular death, progression to severe functional limitation, cardioembolic stroke, life-threatening ventricular arrhythmias.
  
  
  RESULTS
  Global Dip-MBF was 1.95 ± 0.85, ranging from 0.7 to 5.9 mL/min/g. Dip-MBF tertile cut-off values were: 0.73 to 1.53 mL/min/g (lowest), 1.54 to 2.13 mL/min/g (middle), and 2.14 to 5.89 mL/min/g (highest). During follow-up, lowest tertile Dip-MBF was associated with sevenfold independent risk of unfavorable outcome compared to the other two tertiles. Dip-MBF 1.35 mL/min/g was identified as the best threshold for outcome prediction. Regional perfusion analysis showed that all cardiac deaths (n = 4) occurred in patients in the lowest tertile of lateral wall Dip-MBF (≤1.72 mL/min/g); septal Dip-MBF was not predictive.
  
  
  CONCLUSIONS
  Dip-MBF confirms its role as potent predictor of outcome in HCM. However, the threshold for prediction in a contemporary cohort is higher than that reported in earlier studies. Dip-MBF impairment in the lateral wall, possibly reflecting diffuse disease extending to non-hypertrophic regions, is a sensitive predictor of mortality in HCM.
authors.affiliation: Department of Experimental and Clinical Biomedical Sciences - Nuclear Medicine Unit, University of Florence, Largo Brambilla 3, 50134, Firenze, Italy.
authors.forename: Helga
authors.initials: H
authors.lastname: Castagnoli
authors.affiliation: Referral Center for Myocardial Diseases and Genetic Diagnostics Unit, Careggi University Hospital, Florence, Italy.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Ferrantini
authors.affiliation: Referral Center for Myocardial Diseases and Genetic Diagnostics Unit, Careggi University Hospital, Florence, Italy.
authors.forename: Raffaele
authors.initials: R
authors.lastname: Coppini
authors.affiliation: Department of Experimental and Clinical Biomedical Sciences - Nuclear Medicine Unit, University of Florence, Largo Brambilla 3, 50134, Firenze, Italy.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Passeri
authors.affiliation: Referral Center for Myocardial Diseases and Genetic Diagnostics Unit, Careggi University Hospital, Florence, Italy.
authors.forename: Katia
authors.initials: K
authors.lastname: Baldini
authors.affiliation: Department of Experimental and Clinical Biomedical Sciences - Nuclear Medicine Unit, University of Florence, Largo Brambilla 3, 50134, Firenze, Italy.
authors.forename: Valentina
authors.initials: V
authors.lastname: Berti
authors.affiliation: Referral Center for Myocardial Diseases and Genetic Diagnostics Unit, Careggi University Hospital, Florence, Italy.
authors.forename: Franco
authors.initials: F
authors.lastname: Cecchi
authors.affiliation: Referral Center for Myocardial Diseases and Genetic Diagnostics Unit, Careggi University Hospital, Florence, Italy.
authors.forename: Iacopo
authors.initials: I
authors.lastname: Olivotto
authors.affiliation: Department of Experimental and Clinical Biomedical Sciences - Nuclear Medicine Unit, University of Florence, Largo Brambilla 3, 50134, Firenze, Italy. roberto.sciagra@unifi.it.
authors.forename: Roberto
authors.initials: R
authors.lastname: Sciagrà
mesh_terms: D000328:Adult; D002312:Cardiomyopathy, Hypertrophic / Q000000981:diagnostic imaging* / Q000401:mortality*; D015984:Causality; D015897:Comorbidity; D003324:Coronary Artery Disease / Q000000981:diagnostic imaging* / Q000401:mortality*; D004176:Dipyridamole / Q000008:administration & dosage; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008137:Longitudinal Studies; D008297:Male; D055420:Perfusion Imaging / Q000379:methods*; D049268:Positron-Emission Tomography / Q000379:methods*; D015995:Prevalence; D015203:Reproducibility of Results; D012307:Risk Factors; D012680:Sensitivity and Specificity; D015996:Survival Rate; D014665:Vasodilator Agents / Q000008:administration & dosage
chemical_list: D014665:Vasodilator Agents; D004176:Dipyridamole
keywords: Coronary microvascular dysfunction; Hypertrophic cardiomyopathy; Outcome; Positron emission Tomography