AF Symposium 2015
The Changing Ablation World: Going Beyond PVI With ECGI Mapping and Ablation Techniques
By Steve S. Ryan, May 2015
ECGI is changing everything—not only the way mapping and ablations are done, but also our basic understanding of A-Fib. Instead of potentials and CFAEs, EPs will focus on ablating drivers (rotors and foci). Ablating the PVs will still be basic. But in more difficult cases, EPs must look for non-PV triggers or drivers.
Prof. Michel Haïssaguerre of the French Bordeaux group/LIRYC gave a presentation entitled “Beyond PVI—Mapping and Ablation Techniques for Elimination of Drivers in Persistent AF.” Non-Invasive Electrocardiographic Imaging, or ECGI (from CardioInsight) is a radically new and innovative mapping and ablation system.
The ECGI Vest-Like Device Innovative Mapping and Ablation System
The day before their ablation, the patient lies down on their back and a technician places a vest-like device with 256 electrodes over their chest and stomach. These electrodes combine with rapid CT (Computed Tomography) scans to produce a very detailed 3D color map of the heart.
The system automatically detects rotors and foci and computes them into a “Cumulative Map” or movie. These driver regions are ranked, based on statistical prevalence. They are displayed in statistical density maps which define the ablation roadmap.
The use of ECGI mapping results in a drastic decrease of RF burns needed
Ablation using ECGI results in a drastic decrease of RF burns needed to produce A-Fib termination.
In ECGI, Paroxysmal and Persistent A-Fib Ablation are Different
Paroxysmal: Using ECGI in 41 paroxysmal patients, Dr. Haïssaguerre found that the A-Fib drivers originated from the PV/post LA region. They consisted of PV discharges interacting with short-lived ostial rotors, which is in accordance with current knowledge and practice of A-Fib ablation. (A standard PVI ablation normally targets these areas.)
Persistent: But in 248 persistent A-Fib cases (54% with Structural Heart Disease), he found multiple interplaying A-Fib drivers coming from both atria but usually clustered in 4 regions. (The regions could vary from 1-7.) These drivers were short lived (3-4 reentries/firings) but periodically recurred in the same areas. As one would expect, the number of driver regions increased with the duration of persistent A-Fib. Long-Lasting persistent had 7 driver regions diffused throughout the atria. Cases with only 1 driver region were rare (9%).
Relationship of Drivers and CFAEs
These driver regions overlapped with areas of CFAEs (Complex Fractionated Atrial Electrograms). But whereas CFAEs were found in 49% of the total atrial surface, drivers were found only in 19%. Also, fractionated signals were more frequent and spanned a greater part of the A-Fib cycle length in driver regions than elsewhere (71% vs 47%). (This is good news for patients with persistent A-Fib. With ECGI, much less heart area needs to undergo ablation burns.)
Best Ablation Outcome is A-Fib Termination, But Not Always Possible with Persistent A-Fib
Dr. Haïssaguerre showed slides where he ablated driver regions which transformed rapid complex A-Fib signals into slower organized signals. He stated from his own experience and from several studies that the best outcome of ablation was A-Fib termination into sinus rhythm or tachycardia.
But this result was much harder to achieve in long-lasting persistent A-Fib. In cases where patients had only recently went into persistent A-Fib (1-3 months), 75% had A-Fib termination targeting driver regions. While in long-lasting persistent A-Fib, only 13% had A-Fib termination. Dr. Haïssaguerre’s hypothesis was that early persistent A-Fib is initially driver-dependent, while long-lasting persistent cases progress to widespread substrate disease.
In another study following 90 patients, 85% of patients with A-Fib termination were A-Fib free after 12 months (in the remaining 15%, 54% were paroxysmal). While patients who didn’t have their A-Fib terminated, only 63% were A-Fib free (all were persistent).
What EPs Do When AF Persists After ECGI Driver Ablation
• Check driver regions (including PVs) to ensure abolition of rapid-disorganized EGMs (electrogram signals).
• Body Surface Remapping—to look for new drivers appearing after the first ones are eliminated. Many have observed that this strategy often improves results in difficult cases of long-lasting A-Fib.
Right Atrium Ablation
Dr. Haïssaguerre recommended ablating the right atrium after the left. Right atrium drivers can disappear after left atrium ablation.
Dr. Haïssaguerre’s Conclusions
• Noninvasive mapping visualizes AF drivers which are Multiple, Meandering, ShortLasting and Associated with Complex EGMs (electrogram signals).
• Ablation targeting these AF critical regions allows high rate of AF termination with minimal RF delivery.
• 85% AF freedom at one year when procedural AF termination is achieved.
• Reproducibility in 8 centers in Germany, Belgium and France (AFACART) (Eight centers in Europe are now performing ECGI ablations with similar results.)
Non-PV Triggers: If your EP only ablates the PVs, you should look elsewhere. I just read an O.R. (Operating Report) where the EP only CryoBalloon ablated the PVs. Even though the patient was still in A-Fib after the PVs were ablated, the EP didn’t look for non-PV triggers. He simply shocked the patient back into sinus rhythm and put him on an antiarrhythmic drug. Chances are the patient’s A-Fib will return, since the non-PV triggers in his heart weren’t ablated.
Driver regions overlap with CFAEs—CFAEs can be ignored: In difficult cases of A-Fib, EPs used to spend a lot of time mapping and ablating CFAEs. Sometimes there were so many CFAEs that the EP wound up debulking much of the left atrium. In Dr. Haïssaguerre’s research, CFAEs could cover nearly half of the total atria surface. But with ECGI, only 19% of that area is ablated. ECGI makes the EP’s job simpler and causes less burns on the patient’s heart.
Try to Get Out of Persistent A-Fib: If you haven’t done so already, ask your EP to be Electrocardioverted in order to avoid long-lasting A-Fib which causes atrial remodeling that produces widespread fibrosis and diffuse driver regions.
You may want to try the newer antiarrhythmic drug Tikosyn (dofetilide) which works well in some cases of persistent A-Fib. (When starting Tikosyn, you will have to be hospitalized for three days to get the dosage right and to check for bad side effects.)
Currently some long-standing A-Fib can’t be cured: The best outcome of ablation is A-Fib termination. But some long-lasting persistent cases turn into widespread substrate disease where it’s not always possible to map and ablate drivers. Even the famed Bordeaux group hasn’t yet figured out a way to achieve 100% success when ablating all long-standing persistent A-Fib.
If you have long-standing persistent A-Fib, should you just throw in the towel and give up? No. In Dr. Haïssaguerre experience, 63% of persistent patients who didn’t have their A-Fib terminated were still A-Fib free. You could be in that 63%. Just be realistic and don’t expect miracles.
Last updated: Saturday, May 30, 2015