EHRA 2023 Hot Takes

The European Society of Cardiology (ESC) wrapped up this year's scientific congress in Barcelona, Spain. The event marked the 20th anniversary of the European Heart Rhythm Association (EHRA).

These were the EHRA 2023 research topics that most piqued our interest, apart from a study we reported on separately involving the safety of high power charging cables for electric vehicles in pacemaker patients:

Novel ablation strategy for atrial fibrillation

An innovative three-step ablation approach including ethanol infusion of the vein of Marshall improves freedom from arrhythmias in patients with persistent atrial fibrillation compared to pulmonary vein isolation (PVI) alone, according to late breaking science presented at EHRA 2023. Preliminary results at 10 months are presented, with follow up ongoing until 12 months.

The cornerstone of catheter ablation of atrial fibrillation is complete isolation of the pulmonary veins. However, only 50% to 60% of patients remain in sinus rhythm at two years. Numerous trials of different ablation strategies have failed to demonstrate superiority over PVI.

The Marshall-Plan ablation strategy consists of 1) PVI; 2) ethanol infusion of the vein of Marshall; and 3) a linear ablation set to block the three main anatomical isthmuses to the pulmonary veins (dome, mitral, and cavotricuspid isthmus lines). The technique focuses on anatomical targets that have been individually recognized as important for the initiation or maintenance of atrial fibrillation but have not been collectively targeted in a systematic manner. The current investigators previously reported encouraging results using this strategy in non-randomized studies.

The present study compared 12-month arrhythmia-free survival with the Marshall-Plan ablation strategy versus PVI only. This was a prospective, randomized, parallel group trial of superiority. The trial included 120 patients with symptomatic persistent atrial fibrillation for more than one month. The average age of participants was 67 years and 21 (18%) were women.

Participants were randomized to receive the Marshall-Plan or PVI alone. Follow up occurred at three months, six months, nine months and 12 months during which patients underwent several tests including an electrocardiogram (ECG), echocardiography, stress test, and 24-hour Holter monitoring. Recurrence of arrhythmias was identified using ECG teletransmission, with findings sent to the hospital once a week plus any time the patient had symptoms. The primary endpoint was recurrence of atrial fibrillation or atrial tachycardia lasting more than 30 seconds at 12 months (including a 3-month blanking period) after a single ablation procedure.

The total radiofrequency time was significantly longer in the PVI group (29 minutes) compared with the Marshall-Plan group (23 minutes; p<0.001). The full lesion set was successfully completed in 53 patients (88%) receiving the Marshall-Plan strategy and 59 patients (98%) receiving PVI only. In an intention-to-treat analysis, the recurrence of arrhythmias after an average follow up of 10 months was significantly higher in the PVI group compared with the Marshall-Plan group (18 vs. 8 patients; p=0.026). Follow up will continue until 12 months.

Principal investigator Nicolas Derval, MD, of the University Hospital of Bordeaux, France said that after 10 months of follow up, the success rate in the Marshall-Plan group was significantly better (87%) compared to the PVI only group (70%).

"However, the results are still preliminary as follow up is not completed for all patients, Derval said. "While the findings indicate that the Marshall-Plan strategy holds promise for patients with persistent atrial fibrillation, they need to be confirmed in a multicenter trial.”

Guidance on natural pacemaker method discussed at EHRA 2023

An international consensus statement on the safest and most effective way to implant a pacing system that mimics the heart’s normal function was published this week in EP Europace, a journal of the ESC. The document was launched at the EHRA Conduction System Pacing Summit and was discussed at EHRA 2023.

According to Haran Burri, a professor at the University Hospital of Geneva, Switzerland and first author of the new guidance, about 1.4 million people worldwide will receive a pacemaker in 2023. Roughly half of those patients could potentially benefit from conduction system pacing, which connects to the body's own electrical cables and is therefore more physiological than conventional methods, Burri said.

Pacemakers are used to regulate the heart rate in people whose heart beats too slowly, mainly because of a block in the electrical connection between the upper (atria) and lower (ventricles) levels of the heart (called atrioventricular block).

“Standard pacing electrically activates a single point in the ventricle, rather than the whole heart simultaneously, leading to uncoordinated contraction in different areas of the heart. In around one-fifth of patients this can damage the heart and lead to heart failure," Burri said. "Conduction system pacing places leads directly along different sites of the heart’s intrinsic conduction system, leading to simultaneous contraction across the heart.”

Conduction system pacing may also benefit patients with heart failure whose left ventricle is weak and not pumping properly due to an electrical disorder (called left bundle branch block), making it contract out of sync with the right ventricle. The current treatment is cardiac resynchronisation therapy (CRT), which delivers biventricular pacing to coordinate contractions, but it does not work in all patients and requires a more complex system than a conventional pacemaker.

Conduction system pacing was mentioned as a new method in the 2021 ESC pacing guidelines, but it was acknowledged that randomized trial evidence is needed. Use of the technique is growing, with thousands of procedures performed worldwide to date. An EHRA survey of European physicians published last year reported that the main reason for not adopting the method was lack of training. 

“Until now, there was no consensus on how to carry out this procedure and check that it had been done correctly,” Burri said. “This document provides a standardized approach agreed by worldwide experts which should optimize success rates and avoid complications. The guidance will be useful for physicians learning the method and those wishing to improve their technique. The increase in expertise will also enable large, high-quality randomized trials to be conducted.”

The paper describes the implantation technique for two types of pacing: His bundle pacing and left bundle branch area pacing, which are named according to the target site of the heart’s conduction system.

“With His bundle pacing, a simple test can be done to check that the electrical connection has been achieved," Burri said. "Left bundle branch area pacing requires more detailed checks, and the paper outlines what physicians should aim for and what good pacing looks like.”

Advice is given on how to achieve successful lead implantation, and how to avoid and deal with complications. The document is accompanied by 30 figures with detailed illustrations, 11 videos, an executive summary published as a separate paper, and a Key Messages App, all of which are openly accessible and provided at no cost to the worldwide medical community.

“Conduction system pacing is entering mainstream clinical practice and based on limited data, the therapy has a promising future," Burri said. "It is crucial that physicians adopt a standardized approach to ensure that it is delivered safely and effectively. Today’s consensus paper is set to become the reference on how to perform this procedure.”

The international consensus statement was developed by the EHRA, a branch of the ESC, and endorsed by the Asia-Pacific Heart Rhythm Society, Canadian Heart Rhythm Society, and Latin-American Heart Rhythm Society.

Severe COVID-19 linked to 16-fold risk of dangerous life-threatening heart rhythm

Patients with severe COVID-19 requiring mechanical ventilation are 16 times more likely to develop ventricular tachycardia within six months compared to their peers without severe infection, according to research presented at EHRA 2023. Risks of other heart rhythm disorders were also elevated.

“The actual likelihood of developing ventricular tachycardia or other arrhythmias after severe COVID-19 is low for the individual patient, but much higher than in those without severe infection,” said study author Marcus Stahlberg, MD, of the Karolinska Institute in Stockholm, Sweden.

The objective of this study was to investigate the long-term risk of arrhythmias after discharge from an intensive care unit for COVID-19 requiring mechanical ventilation. The researchers used the Swedish ICU register to identify all COVID-19 patients treated with mechanical ventilation and discharged alive from an ICU between March 2020 and June 2021. Each patient was matched by age, sex, and district of residence with up to 10 people in the general population. Multiple compulsory national registries were used to record new diagnoses of arrhythmias after discharge from the ICU.

The primary outcome was hospitalization with ventricular tachycardia, atrial fibrillation, other tachyarrhythmias, or bradycardia/pacemaker implantation. Ventricular tachycardia is a potentially life-threatening heart rhythm disturbance that occurs when the ventricle beats too fast to pump properly causing the body to receive insufficient oxygenated blood. Atrial fibrillation is an irregular and fast heartbeat that causes shortness of breath and raises the risk of stroke. “Other tachyarrhythmias” refers to a fast heartbeat not caused by atrial fibrillation. “Bradycardia or pacemaker implantation” is a combined endpoint of slow heart rate or need for a pacemaker due to slow heart rate.

The researchers analyzed the risk of developing each arrhythmia in severe COVID-19 patients, compared to those without severe COVID-19. The analyses were adjusted for factors linked with the likelihood of heart rhythm disorders including age, sex, high blood pressure, diabetes, high blood lipids, chronic kidney disease, and socioeconomic status (education level, marital status, and income).

The study included 3,023 patients with severe COVID-19 who received mechanical ventilation at a Swedish ICU and 28,463 individuals from the general population who had not been in an ICU with COVID-19 requiring mechanical ventilation (control group). The average age of participants was 62 years and 30% were women.

The average follow up was nine months. In patients who had severe COVID-19, the incidence rates per 1,000 person-years of ventricular tachycardia, atrial fibrillation, other tachyarrhythmias, and bradycardia/pacemaker implantation were 15.4, 78.4, 99.3 and 8.5, respectively. Corresponding incidence rates in the control group were 0.9, 6.0, 6.7 and 0.9, respectively.

Compared to the control group, patients who had severe COVID-19 requiring mechanical ventilation had a 16-fold risk of ventricular tachycardia, 13-fold risk of atrial fibrillation, 14-fold risk of other tachyarrhythmias, and 9-fold risk of bradycardia/pacemaker implantation.

“COVID-19 patients who need mechanical ventilation often have other conditions and adding a heart rhythm disorder may lead to worsened health," Stahlberg said. "These patients should seek medical attention if they develop palpitations or irregular heartbeats after hospital discharge so they can be evaluated for possible arrhythmias.”