title: Is chronotropic incompetence a limitation in the evaluation of myocardial ischemia and prognosis?
abstract: OBJECTIVE
  The aim of this study was to evaluate whether chronotropic incompetence (CI), the inability to reach 85% of the maximal predicted heart rate during exercise, affects the assessment of myocardial ischemia and prognosis in patients undergoing myocardial perfusion single-photon emission computed tomography (MPS).
  
  
  METHODS
  Patients undergoing exercise/rest MPS were studied. Those taking drugs with negative chronotropic properties were excluded. Summed stress, rest, and difference scores (SSS, SRS, and SDS, representing, respectively, the extent and severity of the total perfusion defect, fibrosis, or ischemia) were calculated. Patients were followed up for the occurrence of hard events (death or myocardial infarction) or myocardial revascularization for 36±20 months.
  
  
  RESULTS
  A total of 391 patients were studied; among them, 11.5% had CI. All perfusion scores were higher in patients with CI. On logistic regression, history of myocardial infarction and SDS were found to be independent predictors of CI. On comparing patients with and without CI, the former more often had hard events (12.5 vs. 0.9%, P=0.007) and revascularization (20.0 vs. 8.1%, P=0.003).
  
  
  CONCLUSIONS
  CI was associated with myocardial ischemia. Higher rates of hard events and revascularization were observed in patients with CI, in accordance with the larger extent of myocardial ischemia found in these patients. Performing MPS in the setting of CI may maintain the diagnostic and prognostic abilities of the test.
authors.affiliation: Diagnostic Imaging Clinic (CDPI), Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
authors.forename: Andrea
authors.initials: A
authors.lastname: De Lorenzo
authors.forename: Gabriel
authors.initials: G
authors.lastname: Oliveira
authors.forename: Ana C
authors.initials: AC
authors.lastname: Ramos
authors.forename: Flavia
authors.initials: F
authors.lastname: Pinto
authors.forename: Tamara
authors.initials: T
authors.lastname: Rothstein
authors.forename: Ronaldo S L
authors.initials: RS
authors.lastname: Lima
mesh_terms: D000368:Aged; D016009:Chi-Square Distribution; D003326:Coronary Circulation; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000209:etiology; D017202:Myocardial Ischemia / Q000150:complications / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000401:mortality / Q000503:physiopathology / Q000628:therapy; D055414:Myocardial Perfusion Imaging / Q000379:methods*; D009204:Myocardial Revascularization; D011237:Predictive Value of Tests; D011379:Prognosis; D012307:Risk Factors; D012720:Severity of Illness Index; D013997:Time Factors; D015899:Tomography, Emission-Computed, Single-Photon