Microwave Ablation For Chronic Atrial Fibrillation
Li Poa, M.D., F.A.C.S.
Director of Perioperative Services
Enloe Medical Center
Chico, California
The Future of Cardiac Intervention (National Health Council)
Stent and intravascular intervention expected to double over next 3 years
CABG volume to decline about 10% with cardiac surgery primarily expanding in EPS and CHF such as ablative surgery, biventricular pacing, LV remodeling, and cardiac muscle augmentation.
Valvular volume to increase about 20% by 2005
Chronic Atrial Fibrillation
Affects 2 million people in the US alone with a 9% 5 year morbidity from anticoagulation and a 5% / year risk of stroke
As high as an 80 % risk of stroke at 8 years in the Japanese study group (Kitamura)
Available treatment modalities include surgical “Maze”, cryotherapy, radiofrequency, irrigating radiofrequency, microwave, and laser
Surgical Maze success best overall but Microwave has the least complications and the best ease of use
Microwave Ablation: ~ 3000 patients
Open Heart
2300 patients
75% success - 0 to 4 year follow up
Beating Heart – Off-Pump
700 patients
80% success - 0 to 2 year follow up
No adverse events
MIS – Off-Pump
Mini Thoracotomy 3 cases
Robotic 2 cases
Thoracoscopy 2 cases
2 cm - FLEX 2TM
4 cm - FLEX 4TM
7 cm - FLEX 7
“...specimens were characterized by myocellular damage involving the full thickness of the atrial wall, where thickness ranged from 4 - 5 mm to 1 cm.”
Clinical Histopathology and Ultrastructural Analysis of Myocardium following Microwave Energy Ablation
Eric Manasse MD, Piergiuseppe Colombo MD, Paola Braidotti PhD,
Massimo Roncalli MD-PhD, Roberto Gallotti MD
(submitted to the Annals of Th. Surg.)
from: In Vitro and In Vivo Evaluation of the Thermal Patterns and Lesions
of Catheter Ablation with a Microwave Monopole Antenna
David Keane MD, Ph.D., Jeremy Ruskin MD,
Nancy Norris, Pierre-Antoine Chapelon, Dany Berube, Ph.D.
Beating-Heart Surgery
Epicardial ablation
Endocardial view
Transmural Lesion
Viable Tissue
Beating-Heart Surgery
Dr. Maessen - Maastricht, Netherlands
(Off-pump)
40 patients (32 cAF, 8 pAF)
acute discharge FU
40/40 26/39 32/39 (82%)
10 patients 8 - 11 months
10 patients 6 - 8 months
19 patients 0 - 6 months
Presented at ISMICS - 2002
n = 31 (mitral valve)
26/31 (84%) in sinus rhythm
Dr. Zembala - Zabrze, Poland
(Arrested Heart)
Presented at CTT - 2002
29 patients (concomitant surgeries)
14 MV - 15 CABG
92% in NSR
Follow-up:
8 patients more than 6 months
21 patients between 1 and 5 months
submitted to the Annals of Th. Surg. - 2002
Prof. Schutz - Munich, Germany
(Arrested Heart)
14 patients (beating-heart and arrested-heart)
79% in NSR (11/14)
64% without AA drug
Follow-up:
mean 131 days (63 - 331 days)
Prof. Gallotti / Dr. Manasse - Milan, Italy
(Arrested Heart)
Presented at CTT - 2002
12 patients (on-pump, concomitant surgeries)
75% in NSR
Follow-up:
up to 3 months
Dr. Gillinov - Cleveland Clinic
(Arrested Heart)
Dresden Experience
211 consecutive patients with documented atrial fibrillation for average of 6.8 years
concomitant MVR, CABG, AVR, and TVR
Survival 98%, no MW complications
70% NSR at 6 months
68% NSR at 1 year with normal atrial transport function
23% had a postop PPM implant
The International Medical Group Conference
“How to Treat Atrial Fibrillation During Mitral Valve Surgery”,
Anno Diegeler, 21 July 2001
The Dresden experience - Dr. Michael Knaut
(Arrested Heart)
Patient Population: n = 120
At least 6 months of documented chronic AF
Refractory to at least 2 AA drugs
1 Year Results: 70-75% in sinus rhythm (n = 60)
Sub-Populations
Bypass: 60% in sinus rhythm
Mitral replacement: 70% in sinus rhythm
Mitral repair: 71% in sinus rhythm
Tricuspid: 75% in sinus rhythm
Aortic: 85% in sinus rhythm
Comparative study on Concomitant Atrial Fibrillation
Group A - 62 patients with no ablation during surgery
survival 94.2%
NSR in 6% of MVD; 9% with CAD; and 5% with AVD disease processes
Group B - 88 patients receiving MW ablation with their surgery
survival 98%
NSR in 62% of MVD; 70% with CAD; and 82% with AVD disease processes
Knaut, M; et al
Dresden, Germany
10- 15 patients per subgroup
Microwave = 91% (11/12 NSR)
Radiofrequency = 65%
Cryoablation = 55%
7 to 12 month follow-up
Presented at EACTS - 2001
Dr. Graffigna - Trento, Italy
(Arrested Heart)
Dr. Kshettry & Dr. Saltman
Minneapolis & Stony Brook
(Off-pump)
21 cAF patients (all Mitral Valve)
Submitted STS - 2003
Acute
13 (62%) NSR
5 (24%) paced rhythm
1 ( 7%) JCT rhythm
2 (10%) AF
Follow-up (1 - 3 months) (n = 20)
17 (85%) NSR
3 (15%) AF
Dr. David Kress and Dr. Murali Dharan
20 patients (18 epicardial, 2 endocardial)
100% left OR in sinus or paced rhythm
75% free of AF at discharge
73% of chronic pts free of AF at 3 months (11/15)
80% pf paroxysmal pts free of AF at 3 months (4/5)
No perioperative complications, deaths, or collateral damage
Presented at NASPE, May 2002
Presented at NASPE, May 2002
Dr. Tom Molloy Portland, OR
19 patients (9 off-pump, 10 on-pump)
100% left OR in sinus or paced rhythm
62% free of AF at discharge
89% of pts free of AF at last follow-up (17/19)
Only 37% (7/19) are still on anti-arrhymthic drug
Presented at New Era, January 2003
Dr. Donald Thomas Chicago, IL
22 patients (11 off-pump, 11 on-pump)
100% left OR in sinus or paced rhythm
86% of pts (19/22) free of AF at last follow-up
Submitted to ISMICS, 2003
Cardiology EP Experience
Primary foci appear to be at endovascular muscular sheaths at vascular insertion points
initial attempts at primary ablation within pulmonary veins led to pulmonary vein stenosis
Present EP technique involves encircling pulmonary vein orifices ablating on endocardial surface of atrium but presently takes an average of 5-6 hours in expert hands using catheter based approach.