POLAR ICE
Research type
Research Study
Full title
POLARx Cardiac Cryoablation system Post Market Clinical Follow-up study
IRAS ID
281292
Contact name
Nele Cielen
Contact email
Sponsor organisation
Boston Scientific International S.A.
Clinicaltrials.gov Identifier
Duration of Study in the UK
2 years, 6 months, 1 days
Research summary
Summary of Research
The purpose of the POLAR ICE study is to collect data about the safety and effectiveness of the Boston Scientific Cardiac Cryoablation System for the treatment of an irregular heart rhythm. This irregular heart rhytm affects the top chambers of the heart and is called atrial fibrillation (AF).
A common treatment for atrial fibrillation is called an ablation procedure. An ablation procedure uses heat or cold (energy) to scar the areas of the heart which are known to trigger atrial fibrillation.
The ablation procedure that will be performed for this study, will be using cryo (cold) energy, it will be the same procedure that a patient would undergo if they were not participating in the study.
The data will be collected before, during and after the participant’s ablation procedure. Participants will also need to return to the hospital for follow-up visits at 3, 6 and 12 months after the ablation procedure.
All subjects signing the consent, undergoing the index procedure and treated with the study devices will be followed up for one year.
Summary of Results
The POLAR ICE study is a clinical study that collects data on patients who agree to have an ablation procedure with the Boston Scientific Cardiac Cryoablation System, also called the POLARx Cryoablation System. Boston Scientific is a medical device company that owns and manufactures the POLARx Cryoablation System and is sponsoring the POLAR ICE study. All patients who agree to participate in the study have an irregular heart rhythm condition called atrial fibrillation and undergo a catheter ablation procedure to try to prevent the atrial fibrillation from occurring.
The Cryoablation System has already received CE mark, which means that the system was approved by European Notified Bodies to be commercially available and used as a regular treatment for atrial fibrillation in European hospitals. The POLAR ICE study was designed after receiving CE mark in order to collect more evidence to demonstrate that the Cryoablation System continues to be safe and effective.
Patients who were asked to participate in the POLAR ICE study suffer from a heart condition called paroxysmal atrial fibrillation. This is a condition where the heart beats rapidly and/or irregularly from time to time and it is unpredictable when these episodes will occur or how long they will last. Atrial fibrillation may cause the patient to feel unwell or have shortness of breath, or feel faint due to the irregular heartbeat. To try to restore the normal heart rhythm, a doctor has decided that the patient needed to undergo an ablation.
Atrial fibrillation is felt to typically come from the pulmonary veins in the heart. The pulmonary veins are the veins that return blood from the lungs to an upper chamber of the heart called the left atrium. During an ablation procedure, the pulmonary veins are ablated which means that the heart tissue around the opening of each pulmonary vein will be permanently damaged and the electrical impulses will no longer be able to travel from the pulmonary veins to the heart. The result of the ablation is that the pulmonary veins are isolated from the rest of the heart tissue and cannot cause the irregular heart rhythm anymore.
In the POLAR ICE study, the ablation procedure was performed with the POLARx Cryoablation System, which used freezing temperatures to ablate the heart tissue that connects the pulmonary veins to the rest of the heart. This prevents the atrial fibrillation from spreading to the left atrium.
Patients who agreed to participate to the study signed a consent form and were followed by the study doctor for 1 year after the ablation procedure. This included a follow-up visit at 3, 6 and 12 months. At the 6 and 12 month visits, patients were also asked to perform a Holter assessment, which is an assessment used to continuously monitor the patient’s heart rate and look for episodes of atrial fibrillation.A total of 400 patients agreed to participate in this study, and they come from Belgium, Croatia, France, Germany, Italy, Spain, the Netherlands and the United Kingdom. The first patient agreed to participate in the POLAR ICE study in August 2020. The last study assessment took place in September 2022. Of these 400 patients, study participation ended for 39 patients before the 12 month visit took place, 1 patient ended participation to the study and also requested to not use their collected data for analyses, and 1 patient died in the year after the ablation procedure. This death was not related to the procedure or the Cryoablation System.
To demonstrate the safety aspect of the Cryoablation system, it was verified how many patients did not experience a safety event that was caused by the ablation procedure or by the use of the Cryoablation system, in the year following the ablation procedure.
These safety events, that were specified before the study was started by the POLAR ICE study team, include the following:
• Death;
• Myocardial infarction, which is a lack of blood supply to the heart that may result in a heart attack;
• Persistent gastroparesis/injury to the vagus nervus, which is a condition in which the digestion slows down and food stays in the body longer than it should. This occurs when the vagus nerve, which controls how quickly the stomach empties, is injured;
• Transient ischemic attack, which is a temporary lack of enough blood and oxygen to the brain;
• Stroke/cerebrovascular accident, which is a loss of blood flow to a part of the brain, damaging brain tissue;
• Thromboembolism/air embolism, which is when air bubbles enter a vein or artery and cause a block within the vessel;
• Cardiac tamponade/perforation, which is blood in the sac surrounding the heart or a hole in the artery or vein or wall of the heart;
• Pneumothorax, which is a collapsed lung;
• Vascular access complications, such as a collection of blood outside of the blood vessels, an abnormal connection between an artery and a vein, leaking of blood in surrounding tissues, a cut, bleeding or an hemorrhage, resulting in a prolongation of the hospitalization, or requiring a surgical intervention or a blood transfusion
• Pulmonary edema/heart failure, which is excessive fluid in the lung, or when the heart doesn’t pump as well as it should;
• Atrio-Ventricular block, which means that the heart’s electrical impulses are blocked, that was not a result of a medication or of fainting due to a drop in blood pressure
From a statistical point of view, the Cryoablation System would be considered safe if more than 86% of the patients did not experience any of the above listed safety events. This is called the safety performance goal.To demonstrate the effectiveness of the Cryoablation System, which is the ability of the device to keep the atrial fibrillation from occurring in the future, it was verified how many patients did not experience atrial fibrillation in the year following the ablation procedure. Failure events include the following:
• Not all veins could be successfully damaged (or isolated) during the ablation procedure;
• Patients needed more than one additional ablation procedure in the 3 months after the initial ablation procedure;
• In the period of 3 to 12 months after the ablation procedure, patients experienced another episode of atrial arrhythmia or needed an intervention to treat the arrhythmia. These interventions could have been a change in the medication, an additional ablation procedure, or a cardioversion, which is a treatment that uses quick, low-energy shocks or drugs to restore a regular heart rhythm.
From a statistical point of view, the Cryoablation System was considered effective if more than 50% of the patients did not experience such a failure event. This is called the effectiveness performance goal.After analyses of the collected data, it was shown that 95.4% of all patients did not experience a safety event as listed above, in the year following the ablation procedure. Since this percentage is larger than a limit value of 86%, the Cryoablation System continues to be considered safe. A total of 19 safety events were observed in 18 subjects, and these safety events included myocardial infarction (1 event), a phrenic nerve injury that was not resolved at 12 months after the ablation procedure (1 event), a persistent gastroparesis/injury to the vagus nervus (1 event), a stroke/cardiovascular accident (1 event), cardiac tamponade/perforation (2 events), thromboembolism/air embolism (2 events) and serious vascular access complications (11 events in 10 patients).
In 92% of patients, the ablation procedure was successful, meaning that all pulmonary veins were successfully ablated during the procedure. In addition, it was shown that 62.1% of the patients did not experience a failure event in the year following the ablation procedure. Since this percentage is larger than the effectiveness performance goal of 50%, the Cryoablation System is considered effective. The failure events that were reported in the study include the need for anti-arrhythmic medication after 3 months, the need for an additional ablation procedure, an episode of an atrial arrhythmia such as atrial fibrillation, or an unsuccessful ablation procedure.
These results from the POLAR ICE study have shown that the Boston Scientific Cardiac Cryoablation System is safe and effective for the treatment of patients with paroxysmal atrial fibrillation.Finally, the entire POLAR ICE study team and Boston Scientific would like to thank all participants of the POLAR ICE study for their interest and their dedication.
REC name
Wales REC 6
REC reference
20/WA/0203
Date of REC Opinion
21 Jul 2020
REC opinion
Favourable Opinion