Carotid Stenosis

..................................................................................................................... 1 Sammanfattning på svenska (Swedish Summary) ................................................. 3 Abbreviations and Glossary ..................................................................................... 5 Original Papers ......................................................................................................... 8 Foreword .................................................................................................................... 9 Introduction ............................................................................................................. 10 General risk factors and treatment for Stroke ...................................................... 10 The pathophysiology of carotid stenosis ............................................................. 12 Atherosclerosis .................................................................................................... 12 The clinical appearances of carotid stenosis ........................................................ 12 Hemodynamic or embolic? .................................................................................. 13 Crossover embolization ....................................................................................... 15 Carotid occlusions ............................................................................................... 17 Carotid near-occlusions ...................................................................................... 18 Management of carotid stenosis .......................................................................... 20 History ................................................................................................................. 20 Carotid surgery and angioplasty .......................................................................... 20 Medical management of patients with carotid stenosis ....................................... 21 Carotid imaging .................................................................................................... 23 Diagnostic tests in general ................................................................................... 23 Measurements of carotid stenosis ........................................................................ 24 Imaging modalities .............................................................................................. 25 Translating flow velocities to percent diameter reduction ................................... 27 Choosing translation method – systematic review and consensus conference .... 27 Are non-invasive modalities accurate enough for clinical decisions? ................. 28 What modality should be used for screening? ..................................................... 29 Is confirmation with conventional angiography required? .................................. 29 Using multiple non-invasive modalities .............................................................. 30 Should confirmation with another non-invasive modality be routine? ............... 32 Patient Selection to Carotid Intervention ........................................................... 33 Subgroup interpretations in general ..................................................................... 33 Subgroup differences for symptomatic carotid stenosis ...................................... 34 Assessing the medical risk: the carotid risk model .............................................. 35 Assessment of treatment effect: the PARRCEA table ......................................... 36 Comparison of the carotid risk model and the PARRCEA table ......................... 41 Asymptomatic carotid stenosis: the past, present and future ............................... 42 Background of the studies in this thesis ................................................................ 44 HUS study ........................................................................................................... 44 ANSYSCAP study .............................................................................................. 44 PtU study ............................................................................................................. 45 Aims .......................................................................................................................... 48 Methods .................................................................................................................... 49 The standardized preoperative evaluation before CEA at Umeå Stroke Centre .. 49 HUS Study ............................................................................................................ 50 Population ascertainment..................................................................................... 50 Inclusion criteria .................................................................................................. 50 Registered parameters and analyses .................................................................... 50 ANSYSCAP Study ............................................................................................... 51 Population ascertainment..................................................................................... 51 Inclusion criteria .................................................................................................. 51 Registered parameters and analyses .................................................................... 51 PtU Study .............................................................................................................. 54 Population ascertainment..................................................................................... 54 Inclusion criteria .................................................................................................. 54 Registered parameters and analyses .................................................................... 54 Reference persons ................................................................................................ 55 Imaging methods ................................................................................................. 56 General Methods .................................................................................................. 56 Definitions and outcomes .................................................................................... 56 Statistical methods ............................................................................................... 56 Ethics ................................................................................................................... 57 Results ...................................................................................................................... 58 HUS and ANSYSCAP: Population description ................................................. 58 HUS Study ........................................................................................................... 58 ANSYSCAP study .............................................................................................. 58 HUS and ANSYSCAP: Delay to CEA ................................................................ 60 Presenting event – CEA in the HUS Study ......................................................... 60 Presenting event – CEA in the ANSYSCAP Study ............................................. 61 Different parts of the management chain in both studies .................................... 61 HUS and ANSYSCAP: Additional symptoms ................................................... 65 HUS Study ........................................................................................................... 65 ANSYSCAP Study .............................................................................................. 65 ANSYSCAP study: Risk of ipsilateral ischemic stroke recurrence ..................... 65 Perioperative risk ................................................................................................. 68 PtU study ............................................................................................................... 69 Discussion................................................................................................................. 72 HUS study ............................................................................................................. 72 Main findings ...................................................................................................... 72 The delay to CEA – including the data from the ANSYSCAP study .................. 72 Limitations .......................................................................................................... 72 Summary ............................................................................................................. 73 ANSYSCAP study ................................................................................................ 74 Main findings ...................................................................................................... 74 Design.................................................................................................................. 74 Comparison to previous similar studies ............................................................... 74 Subgroup findings ............................................................................................... 75 Power calculation ................................................................................................ 76 Limitations .......................................................................................................... 78 Interpretation ....................................................................................................... 79 Speculations on the possible impact .................................................................... 80 Summary ............................................................................................................. 82 PtU study ............................................................................................................... 83 Main findings ...................................................................................................... 83 Design.................................................................................................................. 83 Comparison to previous similar studies ............................................................... 83 Subgroup findings ............................................................................................... 84 Limitations .......................................................................................................... 84 Interpretation ....................................................................................................... 84 Experiences from clinical implementation .......................................................... 85 Speculations on the possible impact .................................................................... 85 Summary ............................................................................................................. 86 General Discussion ............................................................................................... 87 Possible alternative data sources ......................................................................... 87 Statistics .............................................................................................................. 87 Ethics ................................................................................................................... 88 For the clinician that manages patients with stroke ............................................. 88 Personal views ..................................................................................................... 89 Conclusions .............................................................................................................. 90 Acknowledgments ................................................................................................... 91 References ................................................................................................................ 93 Appendix: Papers I-IV