title: The relationship between the contralateral collateral supply and myocardial viability on cardiovascular magnetic resonance: can the angiogram predict functional recovery?
abstract: BACKGROUND
  A collateral circulation which supplies a myocardial territory, subtended by a chronic total occlusion (CTO), may be observed at invasive coronary angiography. The prognostic and protective role of such collateralisation is well demonstrated suggesting that a good collateral circulation may be a predictor of myocardial viability, but current evidence is discrepant. The aim of this study is to assess the relationship between collateralisation from the contralateral epicardial vessels and myocardial viability by cardiovascular magnetic resonance (CMR).
  
  
  METHODS
  Consecutive patients with CTO having had both CMR and invasive coronary angiography were retrospectively identified. The collateral circulation was graded with the Cohen and Rentrop classification. CMR images were graded per segment for wall motion (1: normal/hyperkinetic, 2: hypokinetic, 3: akinetic, or 4: dyskinetic) and wall motion score index (WMSI) was calculated. The segmental transmurality of late gadolinium enhancement was scored as 1 (0%), 2 (1-25%), 3 (26-50%), 4 (51-75%) and 5 (76-100%).
  
  
  RESULTS
  A good collateral circulation was more likely to supply viable myocardium (p=0.01). There was no relationship between collateral circulation supply and wall motion score index (WMSI), however, increasing transmurality of LGE was significantly associated with higher mean WMSI representing increasing dysfunctional myocardium (p<0.001).
  
  
  CONCLUSIONS
  The presence of collateral coronary circulation at angiography predicts the presence of viability on cardiovascular MRI, with a gradation of greater viability associated with improving Rentrop grade. A collateral circulation at angiography should, therefore, prompt more formal assessment of viability and consideration of revascularisation in order for the patient to obtain the associated functional and prognostic improvement.
authors.affiliation: Cardiovascular Magnetic Resonance Unit, Royal Devon & Exeter NHS Foundation Trust, Barrack Road, Exeter EX2 5DW, United Kingdom; University of Exeter, Barrack Road, Exeter EX2 5DW, United Kingdom.
authors.forename: David P
authors.initials: DP
authors.lastname: Ripley
authors.affiliation: Cardiovascular Magnetic Resonance Unit, Royal Devon & Exeter NHS Foundation Trust, Barrack Road, Exeter EX2 5DW, United Kingdom; University of Exeter, Barrack Road, Exeter EX2 5DW, United Kingdom.
authors.forename: Oliver E
authors.initials: OE
authors.lastname: Gosling
authors.affiliation: University Hospital Southampton NHS Foundation Trust, Tremona Road, Southampton SO16 6YD, United Kingdom; Faculty of Medicine, University of Southampton, United Kingdom.
authors.forename: Loke
authors.initials: L
authors.lastname: Bhatia
authors.affiliation: University Hospital Southampton NHS Foundation Trust, Tremona Road, Southampton SO16 6YD, United Kingdom; Faculty of Medicine, University of Southampton, United Kingdom.
authors.forename: Charles R
authors.initials: CR
authors.lastname: Peebles
authors.affiliation: University of Exeter, Barrack Road, Exeter EX2 5DW, United Kingdom.
authors.forename: Angela C
authors.initials: AC
authors.lastname: Shore
authors.affiliation: University Hospital Southampton NHS Foundation Trust, Tremona Road, Southampton SO16 6YD, United Kingdom; Faculty of Medicine, University of Southampton, United Kingdom.
authors.forename: Nick
authors.initials: N
authors.lastname: Curzen
authors.affiliation: Cardiovascular Magnetic Resonance Unit, Royal Devon & Exeter NHS Foundation Trust, Barrack Road, Exeter EX2 5DW, United Kingdom; University of Exeter, Barrack Road, Exeter EX2 5DW, United Kingdom. Electronic address: nick.bellenger@nhs.net.
authors.forename: Nick G
authors.initials: NG
authors.lastname: Bellenger
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003097:Collateral Circulation / Q000502:physiology*; D017023:Coronary Angiography / Q000379:methods; D003331:Coronary Vessels / Q000000981:diagnostic imaging* / Q000502:physiology*; D005260:Female; D006801:Humans; D019028:Magnetic Resonance Imaging, Cine / Q000379:methods; D008297:Male; D008875:Middle Aged; D009206:Myocardium; D011237:Predictive Value of Tests; D020127:Recovery of Function / Q000502:physiology*; D012189:Retrospective Studies
keywords: Chronic total occlusion; Collateral circulation; Magnetic resonance imaging; Viability