title: Antiarrhythmic and anti-ischaemic effects of angina in patients with and without coronary collaterals.
abstract: OBJECTIVE
  To determine whether the changes in the manifestations of myocardial ischaemia during sequential angina episodes caused by exercise or coronary artery occlusion are collateral dependent.
  
  
  METHODS
  40 patients awaiting percutaneous transluminal coronary angioplasty for an isolated left anterior descending artery stenosis underwent three sequential treadmill exercise tests, with the second exertion separated from the first by 15 minutes, and from the third by 90 minutes; 28 patients subsequently completed two (> 180 s) sequential intracoronary balloon inflations with measurement of collateral flow index from mean coronary artery wedge, aortic, and coronary sinus pressures.
  
  
  RESULTS
  On second compared with first exercise, time to 0.1 mV ST depression (mean (SD): 340 (27) v 266 (25) s) and rate-pressure product at 0.1 mV ST depression (22 068 (725) v 19 586 (584) beats/min/mm Hg) were increased (all p < 0.005), while angina and ventricular ectopic beat frequency were diminished (p < 0.05). This advantage, which had waned by the third effort, was independent of collateral flow index. Similarly, at the end of the second compared with the first coronary occlusion, ventricular tachycardia (21% v 0%, p < 0.05), ST elevation (0.47 (0.07) v 0.33 (0.05) mV, p < 0.005), and angina severity (6.1 (0.7) v 4.6 (0.7) units, p < 0.005) were reduced despite similar collateral flow indices.
  
  
  CONCLUSIONS
  In patients with coronary artery disease, ventricular arrhythmias, ST deviation, and angina are reduced during a second exertion or during a second coronary occlusion. This protective effect can occur independently of collateral recruitment. These characteristics, together with the breadth and temporal pattern of protection, are consistent with ischaemic preconditioning.
authors.affiliation: Department of Cardiology, GKT School of Medicine, St Thomas' Hospital, London, UK.
authors.forename: R J
authors.initials: RJ
authors.lastname: Edwards
authors.forename: S R
authors.initials: SR
authors.lastname: Redwood
authors.forename: P D
authors.initials: PD
authors.lastname: Lambiase
authors.forename: E
authors.initials: E
authors.lastname: Tomset
authors.forename: R D
authors.initials: RD
authors.lastname: Rakhit
authors.forename: M S
authors.initials: MS
authors.lastname: Marber
mesh_terms: D000368:Aged; D000787:Angina Pectoris / Q000209:etiology / Q000503:physiopathology*; D015906:Angioplasty, Balloon, Coronary / Q000379:methods; D001145:Arrhythmias, Cardiac / Q000503:physiopathology*; D003097:Collateral Circulation / Q000502:physiology*; D023921:Coronary Stenosis / Q000150:complications* / Q000503:physiopathology / Q000628:therapy; D004452:Echocardiography / Q000379:methods; D015444:Exercise / Q000502:physiology; D005080:Exercise Test; D005260:Female; D006801:Humans; D019157:Ischemic Preconditioning, Myocardial / Q000379:methods; D008297:Male; D008875:Middle Aged; D017202:Myocardial Ischemia / Q000209:etiology / Q000503:physiopathology