Catheter Ablation for Atrial Fibrillation

Catheter ablation of atrial fibrillation (AF; AF ablation) is a method of cardiology that can be used to eliminate AF after an electrophysiologic study (EPU). Ablation (lat. ablatio “ablation, detachment”) of the tissue parts that send pathological (diseased) electrical impulses is performed using a catheter-based procedure by inducing a scar. The local destruction of the tissue (= scar) can interrupt the incorrect transmission of the electrical impulses. Ablation of the tissue is performed following the electrophysiological examination, during which electrical signals are registered at various points in the heart via the electrode catheters and any cardiac arrhythmia present is triggered by inducing pacemaker pulses. For ablation of the tissue, radiofrequency ablation (radiofrequency ablation) is the most commonly used method, in which the use of electricity is used to heat the tissue in the heart, creating a scar that no longer has electrical activity. Radiofrequency ablation is equal to antiarrhythmic therapy or, if necessary, is even the superior treatment method for many patients. Compared to therapy with antiarrhythmic drugs, patients with catheter ablation have been shown to have better short- and long-term treatment success. The classic patient receiving catheter ablation is a 60-year-old male with paroxysmal atrial fibrillation with no apparent cause. In patients without structural heart disease (SH), symptom freedom is the curative goal of ablation. Progression rates (progression) after catheter ablation, i.e., the transition from paroxysmal (seizure-like) AF to persistent or permanent AF, are significantly lower than in patients without catheter ablation (10-20% persistent or permanent AF after 1 year or 50-77% after 12 years versus 2.4 to 2.7% 5 years after catheter ablation). Success rates of ablation therapy for supraventricular tachycardia (SVT) are high (usually > 95%) in most forms of supraventricular tachycardia. A new and promising indication for catheter ablation is atrial fibrillation in combination with heart failure/heart failure (CASTLE-AF study).The primary endpoint of the study was a composite of mortality rate and unplanned inpatient admissions due to worsening heart failure. After a mean follow-up period of 37.8 months, the primary endpoint was significantly lower in the ablation group (28.5 percent) than in the control group (44.6 percent). For clarity, all indications for ablation therapy for supraventricular tachycardia are listed below (accepted indications are shown in blue bold type):

Indications (areas of application)

• Supraventricular tachycardia (SVT) – supraventricular tachycardia (rapid cardiac arrhythmia originating in the atria) is the term used to describe tachycardic arrhythmias (ventricular rate > 100 beats per minute) for which anatomic structures above the division of the His bundle are causative; these include:
  • Atrial fibrillation (VHF) – most common indication for the use of cardiac catheter ablation. Atrial fibrillation represents a supraventricular arrhythmia with uncoordinated electrical activation leading to limitation of mechanical function of the atrium. This restriction is particularly problematic due to an increased risk of apoplexy (stroke) to approximately 5% in non-valvular atrial fibrillation. Treatment of atrial fibrillation depends on the stage present. Paroxysmal AF converts spontaneously within 48 hours by definition. Persistent atrial fibrillation, unlike permanent atrial fibrillation, can be cardioverted. According to ESC guidelines, catheter ablation is primarily recommended in symptomatic patients in whom at least one prior attempt at medical therapy has been unsuccessful (Class I recommendation, Level of Evidence A for second-line indication). Confirmed indications are:
    • Therapy of choice in patients with symptomatic recurrences on antiarrhythmic drug therapy.
    • There is an IA recommendation for paroxysmal AF and a IIa/C recommendation for the persistent form.
    • Left ventricular dysfunction (left heart failure; left ventricular weakness) and atrial fibrillation (see CASTLE-AF study below).
  • Current ESC Guidelines 2020:
  • • Patients with paroxysmal or persistent atrial fibrillation for rhythm control after unsuccessful drug therapy or intolerance to class I/III antiarrhythmic drugs (class IA recommendation).
    • For symptom improvement in selected patients with symptomatic paroxysmal atrial fibrillation (IIa recommendation).
    • Atrial fibrillation and left ventricular dysfunction (decreased left ventricular pump function) or heart failure (heart failure) (first-line therapy).
    • In selected patients with heart failure and decreased ejection fraction (HFrEF), ablation should be considered to reduce mortality (death rate) and hospitalization for heart failure (IIa recommendation)
  • Atrial flutter
  • Accessory (additional) pathways
    • AV nodal re-entrant tachycardia (AVNRT).
    • Wolff-Parkinson-White syndrome, WPW)
  • Focal atrial tachycardia (before frequency of 140 to 280 per minute).

Contraindications

Absolute contraindications

• Coagulation disorders – a coagulation disorder that has not been treated or is considered untreatable is an absolute contraindication to the procedure.
• Infections – in the presence of acute generalized infectious disease or infections of the heart in the form of endocarditis (endocarditis) or myocarditis (myocarditis) also represent absolute contraindications.
• Allergy – in the case of an existing allergy to a drug that is used in the treatment, this is to be considered an absolute contraindication.

Relative contraindications

• Reduced general condition – if the risk for the procedure is too great due to reduced general condition, the procedure should not be performed.

Before therapy

Differentiation of various tachycardic arrhythmias is often very difficult in practice. However, an exact differentiation of the arrhythmias is mandatory, because the therapeutic measures sometimes differ fundamentally and an incorrect treatment can cause an aggravation of an existing disease.

• Anamnesis – during the anamnesis, the triggers of the arrhythmias, duration and first occurrence, symptoms, occurrence in the family, and the patient’s own measures to improve the symptoms, among other things, must be addressed. As a rule, no diagnosis can be derived from the history alone.
• Physical examination – the physical examination is composed primarily of auscultation of the heart and lungs, assessment of pulse qualities and blood pressure, and detection of possible signs of heart failure.
• Transesophageal echocardiography (TEE) – to exclude thrombi in the left atrium, more specifically in the left atrial ear [mandatory].
• Anticoagulation (inhibition of blood clotting) – During pulmonary vein isolation (see below), anticoagulation with vitamin K antagonists (VKA) should no longer be interrupted.Probably, the new oral anticoagulants (NOAC) do not need to be discontinued during ablation either. The risk of periprocedural bleeding or thromboembolism does not appear to increase.Caveat: With at least four weeks of pretreatment with NOAC or warfarin (vitamin K antagonists, VKA), left atrial thrombi (thrombi/blood clots in the left atrium) had been detected with the aid of TEE in 4.4% of all patients before catheter ablation (pulmonary vein isolation).
• Electrocardiogram – of critical importance in the detection of cardiac arrhythmias is electrocardiography using a 12-lead surface electrocardiogram. The number of channels has an important influence on the diagnostic reliability of the procedure. If the treating physician has sufficient experience, the ECG can be used to make the correct diagnosis in more than 90% of cases. Despite this high detection rate, it is inevitable to create a detailed “risk profile” in patients with arrhythmias from anamnestic, clinical and non-invasive examination findings and, if necessary, to expand this with invasive measures such as coronary angiography (radiological procedure that uses contrast agents to visualize the lumen (interior) of the coronary arteries (arteries that surround the heart in a wreath shape and supply the heart muscle with blood) if necessary.
• Cardio-computed tomography (synonyms: cardio-CT; CT-cardio, cardiac computed tomography (CT); coronary CT (CCTA)): radiologic examination procedure in which computed tomography (CT) is used to image the heart and its supplying vessels. – Performed to obtain a comprehensive picture of the anatomy of the left atrium; this image data is used, among other things, for three-dimensional electrical reconstruction during the examination.Specificity for the detection of atrial thrombus (blood clot in the atrium) is somewhat higher, since false positive findings are not infrequently obtained during TEE.
• Cardiac magnetic resonance imaging (synonyms: cardiac magnetic resonance imaging (cMRI), cardiac MRI; cardiac MRI; MRI-cardiac; MRI-cardiac): Performed to obtain a comprehensive picture of the anatomy of the left atrium; this image data is used, among other things, for three-dimensional electrical reconstruction during the examination.The examination also provides information on the extent to which there is extensive fibrosis (pathological proliferation of connective tissue) of the left atrium (= atrial fibrosis). The extent of fibrosis correlates with the risk of recurrence (relapse) in the first year of catheter ablation.
• Electrophysiological examination (EPU) – This is a special cardiac catheterization examination in patients with cardiac arrhythmias. The aim of this examination is to determine the nature and mechanism of the underlying cardiac arrhythmia, as well as to accurately locate the origin of tachycardia (mapping = map-like registration of cardiac action currents). Modern three-dimensional (3-D) mapping techniques offer the opportunity to significantly improve the results of catheter ablation by providing a spatial representation of the activation fronts. The procedure: Two to four electrophysiological cardiac catheters (approximately 2-3 mm in diameter) are inserted into the right heart via the inguinal veins under X-ray fluoroscopy. These electrode catheters are used to derive local electrocardiograms at various points in the heart and to trigger a cardiac arrhythmia with the aid of imperceptible pacemaker pulses. The cardiac arrhythmia triggered in this way can be terminated again via the inserted catheters with pacemaker pulses or by fast-acting drugs. Once the cardiac arrhythmia has been diagnosed, the therapy can be planned.As a result, a three-dimensional image of the left atrium and pulmonary veins as well as the electrical activation during the arrhythmia is thus recorded as part of the 3-D mapping procedure. Note: EPU is performed again after pulmonary vein ablation has been performed to be sure that complete pulmonary vein isolation has occurred.

The procedure

The procedure is performed under analgesia (twilight sleep). In ablation for atrial fibrillation, different energy sources are currently the focus of clinical research to achieve optimal complete electrical isolation of the pulmonary veins (pulmonary veins) with as few individual applications as possible. Different methods include highly focused sonography, laser energy (laser ablation), radiofrequency current (radiofrequency ablation or radiofrequency ablation), and cryothermia (cryoablation). The majority of these methods are based on a balloon system, with the balloon placed either in front of or in the pulmonary vein ostium (vascular opening of the pulmonary vessels in the left atrium) for pulmonary vein isolation (PVI) or pulmonary vein ablation (pulmonary vein ablation), respectively. Pulmonary vein ablation destroys tissue in the area of the pulmonary vein, resulting in the interruption of conduction pathways to the left atrium. This effectively prevents a new triggering of atrial fibrillation. Currently, various forms of catheters are used. In contrast to the circular application of energy used in sonography and cryothermy, the application of energy in other methods is crescent-shaped. The success of the various methods is currently the subject of ongoing research. The success rates of radiofrequency ablation (64%; 65%) and cryoablation (63%; 68%) were the same at 6 and 12 months, respectively. However, the complication rate was higher in cryoballoon ablation than in the control group (12, 2 versus 5.0%).The FREEZE cohort study documented that treatment outcomes achieved by cryoballoon or classical radiofrequency current (RF) ablation in patients with paroxysmal or persistent AF were largely the same at experienced centers. Only in the subgroup with paroxysmal AF was cryoballoon ablation associated with a lower risk of recurrence (adjHR 0.80, 95% CI 0.64-0.99; p = 0.047). Furthermore, the rate of repeat catheter ablations (re-ablations) was significantly lower in the cryoballoon group than in the RF ablation group (adjHR 0.46, 95% CI 0.34-0.61; p < 0.0001). In the “Fire and Ice” study, 384 patients were treated by radiofrequency ablation and 378 patients by “Arctic Front Cryoablation System”. The primary endpoint was defined as clinical treatment failure, recurrence of atrial fibrillation/flutter or other atrial tachycardia, or use of antiarrhythmic drugs, or need for repeat ablation. The primary safety end point was defined as the combination of death, cerebrovascular events (ie, apoplexy), or other treatment-related complications .Results: Regarding primary endpoint of clinical failure of treatment: 1-year event rate of 31.9 for radiofrequency ablation and 35.0 percent for “Arctic Front Cryoablation System”.Regarding primary safety endpoint: 1-year event rates were 10.2 for radiofrequency ablation and 12.8 percent for “Arctic Front Cryoablation System”.Regarding complications: Radiofrequency ablation: more frequent groin complications (due to two catheters: ablation catheter and a second catheter for mapping); cryoablation: paresis of the right phrenic nerve (detectable in 10 patients at discharge, 9 recovered within 12 months). Complete pulmonary vein isolation in patients with paroxysmal (seizure-like) AF by gap-free closed ablation lines prevents AF more effectively than incomplete ablation with gap-free lines: event-free rates of 37.8% with complete or 20.8% with incomplete pulmonary vein isolation, and thus a difference of 17.1%, favor complete pulmonary vein isolation (with a 95% confidence interval of 5.3% to 28.9%, p < 0.001). Note: EPU is performed immediately after pulmonary vein ablation has been performed to be certain that complete pulmonary vein isolation has occurred.At three months, electrophysiologic follow-up demonstrated conduction gaps in 70% of patients with initial complete pulmonary vein isolation. Ancillary procedure: Injection of ethanol into the vein of Marshall (vena obliqua atrii sinistri) increased the success rate of catheter ablation in patients with persistent AF. The difference of 11, 2 percentage points was significant (follow-up at 6 and 12 months: 60 of 158 patients (38%) without AF (without further treatment and without medication) versus group with additional injection of ethanol into the vein of Marshall: 91 of 185 (49.2%)).Note: The vein of Marshall, which opens into the coronary sinus, is considered a possible site of origin of AF.

After Therapy

A pressure dressing is applied in the cath lab immediately after the procedure. After therapy, it is necessary for the patient to maintain strict bed rest for 6 (-12) hours. Furthermore, it is advisable to perform inpatient monitoring on the first postoperative day in order to detect possible complications earlier. Showering is generally possible 2 days after therapy. Lifting heavy loads should be avoided for the next 2-3 days. Sexual abstinence is required for one week.Physical rest is advised for the first 10 days after catheter ablation. Sports activity can be taken up after four weeks (heart rate; -110 beats/min. ; indication for patients without beta-blocker therapy); thereafter, a gradual increase in heart rate can take place as part of the training.In the further course, ECG control examinations are necessary in order to be able to check the lasting success of the therapy. Initially, close follow-up care should be regarded as sensible. According to current guidelines, catheter ablation of atrial fibrillation should be followed by at least 8 weeks of anticoagulation (IIaB). Further anticoagulation is based on the CHA 2DS 2-VASc score.After ablation, long-term anticoagulation (inhibition of blood clotting) can probably be omitted, since the harm (hospitalization for severe bleeding) outweighs the benefit (prevention of thromboembolism). Another study showed that long-term therapy with oral anticoagulants should be given to patients with a CHA2DS2-VASc score ≥ 2 (ischemic insults: 1.6% versus 0.3% in patients with continued anticoagulation/rate based on one year). Therapy discontinuers had a 4.6-fold higher risk of apoplexy (stroke risk) with a CHA2DS2-VASc score ≥ 2; with a history of apoplexy, the risk was increased by a factor of 13.7. Antiarrhythmic drugs appear to be of some recurrence-prophylactic benefit in the follow-up after catheter ablation. However, this should not be taken as a plea by the authors for general maintenance of antiarrhythmic medication after catheter ablation. Further references

• The first 3 months after catheter ablation are considered the healing or stabilization phase (“blanking period”). If arrhythmias occur during this period, it is not necessarily a sign of failed catheter ablation.
• If a single episode of atrial fibrillation lasting at least 30 seconds is documented on the ECG (electrocardiogram) or from a cardiac device (eg, pacemaker) after the 3-month blanking period, this is assessed as an “atrial fibrillation” recurrence, and the procedure is considered “unsuccessful” (Heart Rhythm Society, 2007).

Potential complications

• Complication rate depending on the anatomic structure on which the procedure was performed and the method used: cryoballoon: 12.3%; pulmonary vein isolation: 11.7%, left atrial ablation: 13.8%; left + right atrial ablation: 12.7%; right atrial ablation: 10.5%.
• Groin complications (bleeding, hematoma, shock, infection, and vascular complications) in 7.1% of cases; intervention was required in 0.52% of these cases
• Pericardial effusions in 3.5% of cases; therefore, puncture was required in 0.8% of these cases
• Pericardial tamponade/pericardial tamponade (complication of fluid accumulation (see tamponade) in the pericardium; life-threatening complication) (6%); 1.3%; still possible after weeks; symptomatology: collapse of the right ventricle during diastole or a collapse of the right atrium during systole. Furthermore, the inferior vena cava (IVC) is dilated and no longer changes its lumen in a respiratory-dependent manner. Note: Pericardial tamponade is excluded if the IVC collapses during inspiration.
• Asymptomatic phrenic nerve paresis; was observed after cryoballoon ablation in 5.8% of all patients (disappeared after 1 year), whereas after radiofrequency ablation it did not occur in any patient.
• Bradycardia (heartbeat too slow: <60 beats per minute) requiring a pacemaker (1.5%).
• Destruction of portions of the conduction system – ablation may affect portions of the conduction system from the heart, resulting in, for example, thigh block images after the procedure; AV block III°: 0.3%.
• Pulmonary vein stenosis (PVS) – the risk of pulmonary vein stenosis (pulmonary veins) is difficult to avoid due to the localization of ablation. This complication is typically not acute, but rather delayed, often becoming symptomatic after three months to two years. The risk for this complication is currently estimated to be approximately 1-1.5%.
• Apoplexy (stroke; in 1% of patients); 0.6%.
• Silent infarcts (detected by 3 Tesla MRI; in up to 40%).
• Pneumonias 0.8 %
• Thromboembolism – during catheter intervention there is a risk of thrombus formation. Due to the release of the thrombus from the heart, parts of the vessels supplying the brain can be (partially) displaced in the course, so that neurological complications up to apoplexy (stroke) can result from this. To minimize the risk of this complication occurring, a transesophageal echocardiography (ultrasound examination of the heart through the esophagus) is performed prior to the procedure to exclude the presence of thrombi (blood clots). Furthermore, the procedure is performed under anticoagulation (blood clot inhibition), which is continued for three months after the procedure.The risk of thromboembolic events is 0.5% despite preventive measures.
• Atrioesophageal fistula formation (AEF) (approximately 0.03-0.1%) – fistula formation (pathologic connection) between the left atrium and esophagus (food pipe) represents a feared complication. Clinical presentation: Fever, dysphagia (difficulty swallowing), esophagodynia (esophageal pain), chest pain (chest pain), ventricular arrhythmias, neurologic disease (apoplexy (stroke), epileptic seizures, and loss of consciousness; Meningitis (meningitis), brain abscess) and rarely psychiatric abnormalities (confusion, hallucinations)This complication is very rare but usually fatal (lethality: ca. 70 %). The complication occurs 1-5 weeks (3-36 days) after the intervention; if suspected, echocardiography and CT or MRI must be ordered immediately!Note: Gastroscopy (gastroscopy) and transesophageal echocardiography (ultrasound examination of the heart, in which the ultrasound probe is inserted through the esophagus) are contraindicated (not applicable) because of fatal systemic air embolism.
• Mortality (mortality rate; 0.4%).
  • Registry data: 0.1%; age >80 years and heart failure (heart failure) were independently associated with an eightfold risk of mortality; posthospital mortality: 0.09%; for atrial fibrillation ablation, 0.34%
  • Analysis of so-called “real-world data”: early mortality rate (during initial hospitalization or readmission within 30 days; median 11.6 days after ablation): 0.46%; predictors (predictive characteristics) of 30-day mortality are: Heart failure one of the most common causes of re-hospitalization), low case volume at each institution, and procedural complications.

Further notes

• The CHASE-AF trial failed to demonstrate clinical benefits of extensive atrial substrate modification beyond pulmonary vein isolation (PVI) in persistent AF (VHF >7 days).
• Treatment of persistent AF by ablation improved quality of life but was associated with a high recurrence rate of up to 75% after a mean of 46 months. A better outcome was achieved with the aid of computed tomography (CT) during three-dimensional “mapping”: the outcome rate decreased by 61% compared with mapping without CT (OR 0.39; 95% CI 0.19-0.78).
• The ESC-EHRA atrial fibrillation ablation long-term registry of 3,630 patients and 104 participating centers from 27 European countries showed that patients had a mean age of 59 years, 32.4% had no other medical conditions, and 97% suffered from atrial fibrillation-associated symptoms; two-thirds of patients had paroxysmal atrial fibrillation as an indication for ablation; 12 months after the procedure, 73.6% of patients had no detectable atrial arrhythmia, although 45% were still taking antiarrhythmic drugs. On oral anticoagulation, two-thirds of patients were still on antiarrhythmic medication, with decreasing frequency at 12 months.
• Unfavorable predictors of catheter ablation success:
  • Obesity (overweight)
  • Heart failure (cardiac insufficiency)
  • Hypertrophic obstructive cardiomyopathy (HOCM) – the muscles of the left ventricle (heart chamber), especially the ventricular septum, thicken.
  • Obstructive sleep apnea (OSAS) – obstruction (“narrowing”) or complete closure of the upper airway during sleep; most common form of sleep apnea (90% of cases).
• Recommendations for interventional antiarrhythmic recurrence prophylaxis:
  • In persistent AF (duration 1 week to 1 year) or long-standing persistent AF (duration longer than 1 year), interventional or surgical ablation should be considered under special risk-benefit considerations (IIaC).
  • If catheter ablation is unsuccessful, minimally invasive surgical pulmonary vein isolation should be considered (IIaC).
• Catheter ablation (here: radiofrequency catheter ablation) is also superior to drug antiarrhythmic therapy (usually aminodarone) in persistent – that is, persistent or permanent – atrial fibrillation (AF), even in terms of rhythm control. This is especially true for the prevention of recurrence of VHF as well as in the reduction of hospital admissions. The study is based on data from a Cochrane analysis.
• When performing catheter ablation, the “Quality Criteria for the Performance of Catheter Ablation of Atrial Fibrillation” must be observed. These are summarized in the position paper of the German Society of Cardiology.
• CABANA trial: in the “treatment received analysis,” the rate for the primary composite endpoint (death, major stroke, bleeding, and cardiac arrest) was lower in the catheter ablation (pulmonary vein ablation (PVI)) group at 5 years (7.0% vs. 10.9%, p=0.006) as well as the all-cause mortality rate (4.4% vs. 7.5%, p=0.005) were significantly lower than in the drug-only group by 33% and 40%, respectively. The relative risk of recurrence of AF was significantly reduced by 47% by ablation therapy compared to drug therapy.CABANA substudy (results of ECG rhythm recordings during the follow-up period of the study): Atrial fibrillation recurrences by ablation were reduced by almost 50% compared to drug therapy. In contrast, with regard to atrial flutter and atrial tachycardia, there was no difference between catheter ablation and drug therapy.In patients with symptomatic AF, catheter ablation resulted in clinically important and significant improvements in quality of life compared with drug therapy at 12 months.
• CAABLE-AF(California Study of Ablation for Atrial Fibrillation; first retrospective and nonrandomized observational study): Catheter ablation of atrial fibrillation appears to be associated with lower mortality and lower rates of ischemic and hemorrhagic stroke:
  • Significantly lower mortality (death rate) per patient-year (0.9% versus 1.9%, hazard ratio 0.59; p < 0.0001)
  • Period between day 30 and year 5 after catheter ablation: significantly lower rate of ischemic stroke (0.37% vs. 0.59% per patient-year, HR 0.68; p=0.04) and hemorrhagic stroke (0.11% vs. 0.35% per patient-year, HR 0.36; p=0.001) compared with controls
• CASTLE-AF (catheter ablation for VHF in patients with heart failure/heart failure; observation period: 3 years):
  • Decrease in number of patients who died or required hospitalization for heart failure within slightly more than 3 years: medical therapy (44.5%); ablation therapy (28.5%)-relative risk reduction 38%.
  • All-cause mortality: decrease from 25% to 13, 4% – relative risk reduction 48%.
• Meta-analysis based on five studies (CASTLE-AF, ARC-HF, CAMTAF, AATAC, CAMERA-MRI) and one small Scottish study: relative reduction in all-cause mortality of 48% compared with drug therapy (9.0% vs. 17.6%; risk ratio [RR] 0.52 [95% confidence interval 0.33-0.81); risk of hospitalization for heart failure was relatively lower by 40% (16.4% vs. 27.6%; RR 0.60 [95% CI 0.39-0.93]).
• Meta-analysis from 11 randomized trials with a total of 3,598 patients, all of whom had atrial fibrillation (AF) coexisting with heart failure (heart failure): Catheter ablation as a rhythm control strategy improves survival, reduces hospitalization, increases sinus rhythm maintenance rate, contributes to preservation of cardiac function, and improves quality of life in VHF patients complicated with heart failure.
• CAMERA-MRI study (Catheter Ablation Versus Medical Rate Control in Atrial Fibrillation and Systolic Dysfunction): after successful ablation, atrial fibrillation load, LV function (left ventricular function) improved; atrial myocardium (atrial muscle) recovered electrically and structurally (remodeling).
• ATTEST study: catheter ablation of atrial fibrillation appears to significantly delay the transition from paroxysmal to persistent atrial fibrillation compared with antiarrhythmic drug therapy:
  • Patients in the ablation group had a nearly 10-fold lower risk of persistent AF than patients in the control group (hazard ratio: 0.11).
  • In the intention-to-treat (ITT) analysis, the transformation of AF after 3 years was 2.4% in the ablation group and 17.5% in the control group (p=0.0009); the differences were significant in favor of ablation therapy in each case (after year 1: 1.3% vs. 6.5%; after year 2: 2.4% vs.12.4%); the recurrence rate at three years was also significantly lower than in the control group (57.3 vs. 84.7%, p=0.0002).
• Cryo-FIRST study: intention-to-treat analysis showed the following. :
  • 82.2% of patients treated with cold ablation remained free of atrial arrhythmias lasting longer than 30 seconds after a 3-month blanking period (versus 67.6% in the drug group)
  • Over 50% relative risk reduction for arrhythmia recurrence by cryoballoon; thus, significantly more effective than drug treatment.
• Patients are 27% less likely to develop dementia after catheter ablation for atrial fibrillation than after oral anticoagulation. When the analysis was restricted to patients in whom ablation was successful, the risk was reduced by as much as 44%.