Mapping of Ventricular Tachycardia Coronary Artery Disease: Typical - PowerPoint PPT Presentation

What Are We Talking About? Mapping of Ventricular Tachycardia Coronary Artery Disease: Typical patient with scar-related VT Does Entrainment Have a Role in the Era • Substantial scar burden of Substrate Modification? • Decreased ventricular systolic function • Comorbidities (PVD, COPD, etc.) John M. Miller, MD • ICD present Professor of Medicine • Many have had prior cardiac surgery (CABG, valve) Indiana University School of Medicine Krannert Institute of Cardiology • Already taking amiodarone in varying dose Director, Clinical Cardiac Electrophysiology ~ Disclosures ~ Medtronic, Inc. (Research & training support; Consultant; Lecturer) Boston Scientific Corp. (Research & training support; Lecturer) St. Jude Medical (Research & training support; Lecturer) Biosense-Webster, Inc.; Biotronik, Inc. (Training support; Lecturer) Stereotaxis, Inc.; Topera Medical (Advisor Board) What Are We Talking About? What’s “Classical/Entrainment Mapping”? Ideal procedure for ablation in scar-related VT Classical mapping = activation mapping • Readily performed in most patients • Acquiring timing of local electrograms looking for “earliest” activation (macroreentry: mid-diastolic) � Few procedural constraints – Can apply in wide range of patients – heart failure • May be used with or without mapping system � Equipment/skills universally available • Endpoint is termination of VT and non-inducibility – No special electrodes/systems/analytical skills Entrainment mapping - � Achievable endpoints – Measurable outcomes • Assessing presence of concealed fusion during • Good outcomes and PPI or PPI-TCL after pacing at candidate sites � Safety • Sites with (PPI – TCL) < 30 ms are likely in circuit – Acute survival, freedom from complications • Generally requires mapping system � Efficacy • Endpoint is termination of VT and non-inducibility – Freedom from recurrent VT episodes off antiarrhythmic drugs – Survival 1

Entrainment Criteria Classical/Entrainment Mapping Entrainment essentials: Advantages – •Start with stable tachycardia • Familiarity •Overdrive pace till all relevant electrograms are accelerated to • Assurance we are in the right spot (not bystander) paced cycle length • Proof of concept – RF terminates VT •After cessation of pacing, same tachycardia resumes Disadvantages – •Fusion is present during pacing Determining presence of fusion: • Irregular tachycardias - bad news, good news •Know what pure pacing looks like (dissimilar from both • No inducible stable tachycardia tachycardia and pacing during tachycardia) • Difficult interpretation of post-pacing electrograms � Have an example of pure pacing (during sinus rhythm) � Know what pure pacing should look like • Cycle length-dependent conduction slowing •Show graded change in activation at different paced rates • Rarely, best ablation site is systolic (within QRS) (“progressive fusion”) • Multiple tachycardias - spontaneous/induced change •Observe stimulus artifact after onset of accelerated complex Spontaneous Onset at Suspicious Site Entrainment at Site 3:11 PM 3:12 PM S-QRS 58 ms EGM-QRS 58 ms PPI 470 ms PCL 450 ms TCL 470 ms 2

Ablation at Site Substrate Mapping 3:20 PM • Acquire voltage/location data to determine location of: � Barriers to/boundaries for conduction (valve annuli, scar) � Channels of conduction between barriers � Late potentials � Sites with pacemaps similar to known VT morphologies • Advantages: � Treats current VTs, may preclude future arrhythmias � Don’t have to have inducible/mappable tachycardia � Don’t have to know how to do the other stuff • Disadvantages: � Takes time and dense mapping � Lots of ablation; possible volume overload/collateral damage � Accuracy (false positive “scar”) Apical Scar Delineated Substrate-Based Ablation Several techniques have been applied – • Encircle scar region • Radial lines through border zone • Transect conduction channels • Render sites of pacemapping non-capturable • Effect block across ablation line (mitral isthmus) • Elimination of late potentials • Scar homogenization 3

Barriers and Circuit(s) RF Lesions Miss Circuit RF Lesions Transect Circuit Encirclement 4

Connecting Barriers to Transect Circuit(s) Lesion Set Based on Scar Radial Array Late Potential Elimination 5

Voltage Mapping Elimination of Late Potentials with Ablation Pre-Ablation Post-Ablation Late Potential Distribution Voltage Mapping: Specificity Large posterolateral scar: Many LP Large septal scar: No LP 6

Endpoints of Ablation Mapping Techniques Compared What is the best endpoint of ablation? Activation Entrainment Pacemapping Substrate Requires sustained ++ ++++ 0 0 • Inducibility-based tachycardia Requires CL stability 0 ++++ 0 0 � Non-inducibility of clinical VT Requires mapping � Non-inducibility of mappable VT 0 0 0 ++ system (computer) – What is “mappable” vs not varies widely among centers Usable in sinus rhythm 0 0 ++++ ++++ � Non-inducibility of all VTs Sensitive +++ ++++ + ++++ – Hard to achieve in amiodarized patients Specific ++ ++++ + + • Substrate-based Ability to preempt future 0 0 + ++ arrhythmias � Elimination of late potentials Extent of ablation + + ++ ++++ � Rendering areas non-capturable Potential for CHF (fluid; + + ++ ++++ � Completion of lesion set collateral damage) � Demonstration of block on a line (e.g., mitral isthmus) � Homogenization of scar (“seeing red”) What Are We Talking About? Entrainment vs Substrate Mapping Ideal procedure for ablation in scar-related VT Summary – • Readily performed in most patients • Activation and entrainment mapping are powerful Entrain. Substrate tools in treatment of scar-related VTs � Few procedural constraints √√ – Can apply in wide range of patients – CHF √ √ � Proof of being at the correct ablation site � Equipment/skills universally available √ √√ � Reasonable endpoints and outcomes – No special electrodes/systems/analytical skills √ � While these are potent tools, they have wrinkles � Achievable endpoints √ √ – Irregular VT; changing VTs; no inducible VT/unstable VT – Measurable outcomes √√ √ • Substrate mapping is also an excellent tool • Good outcomes � Can be used in all patients � Safety √ √ � Reasonable endpoints and outcomes √ √ – Acute survival, freedom from complications � Not a perfect tool � Efficacy √ √ – Relatively low sensitivity and specificity – Freedom from recurrent VT episodes off drugs √ √ – Substantial time used, volume administered – Survival √ √ 7

Approach to Scar-Based VT Entrainment vs Substrate Mapping VT Present Baseline Conclusions – Yes No • Activation/entrainment and substrate mapping are Electroanatomic Map Electroanatomic Map both very valuable tools for treatment of scar- (chamber dimensions; activation (chamber dimensions; related ventricular tachycardias map; voltage/scar determination) voltage/scar determination) � There will be cases in which one or the other is not Attempt Entrainment practical or proves unreliable Ablate (determine mechanism � It is important for the practicing electrophysiologist to be (interrupt channels, connect barriers) [ablation target characteristics]; facile with both techniques locate ablation target sites) • These should be regarded as complimentary, Ablate Declare Victory rather than “this or that” tools Attempt Reinitiation Inducible VT Yes No 8