title: Do transmyocardial and percutaneous laser revascularization induce silent ischemia? An assessment by exercise testing.
abstract: BACKGROUND
  Transmyocardial and percutaneous laser revascularization (TMR, PTMR) may reduce angina and increase exercise tolerance in otherwise untreatable angina patients, although the mechanism is unknown and the placebo effect may be significant. One other proposed mechanism is cardiac denervation leading to silent ischemia.
  
  
  METHODS
  Electrocardiograms obtained during symptom-limited exercise (ETT, modified Bruce protocol) at baseline and 12 months were analyzed (blinded core laboratory) from 182 patients randomized to TMR (n = 92) or medical therapy alone (MED(TMR), n = 90) and 219 patients randomized to PTMR (n = 109) or medical therapy alone (MED(PTMR), n = 110).
  
  
  RESULTS
  Exercise duration increased 1 year after TMR or PTMR relative to medically treated patients (6.8 +/- 3.4 min vs 8.6 +/- 3.5 min for TMR; 7.3 +/- 3.1 min vs 9.1 +/- 3.6 min for PTMR, P <.05). At baseline, 20% of TMR and MED(TMR) subjects had ST depression >1.0 mm, >80% had angina during exercise, but only 3% had ST changes without chest pain (silent ischemia). This did not change after TMR. In the PTMR group, more subjects exercised to >1.0 mm ST depression (from 17% to 34%, P <.05), with no change in MED(PTMR), but the proportion with silent ischemia did not change in either group.
  
  
  CONCLUSIONS
  Exercise tolerance improved after TMR and after PTMR. Relative to PTMR, TMR more effectively suppressed pain during exercise and ischemic ST depression. However, neither TMR nor PTMR induced significant silent ischemia. These results suggest that denervation may not be a significant factor contributing to angina relief after these procedures. The contribution of the placebo effect was not determined by these results.
authors.affiliation: Palo Alto Veteran's Administration Health Care System, Stanford University, Palo Alto, Calif 94304, USA. DRJ993@aol.com
authors.forename: Jonathan
authors.initials: J
authors.lastname: Myers
authors.forename: Stephen N
authors.initials: SN
authors.lastname: Oesterle
authors.forename: James
authors.initials: J
authors.lastname: Jones
authors.forename: Daniel
authors.initials: D
authors.lastname: Burkhoff
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000787:Angina Pectoris / Q000503:physiopathology / Q000628:therapy*; D017222:Angioplasty, Balloon, Laser-Assisted / Q000009:adverse effects*; D016022:Case-Control Studies; D004562:Electrocardiography; D017079:Exercise Tolerance; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009121:Muscle Denervation; D017202:Myocardial Ischemia / Q000209:etiology*; D009204:Myocardial Revascularization / Q000009:adverse effects* / Q000379:methods