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Blackrock Clinic CEO Blog CEO Welcomes guest authors for special blog series

CEO Welcomes guest authors for special blog series

22nd Jul 2022

Featuring as author Dr Daniel O’Hare, Consultant in Cardiology & Electrophysiology at Blackrock Clinic

“It is a privilege I enjoy every day to meet and converse with the medical and surgical experts who make up the team at Blackrock Clinic. Working within a major Dublin Hi-Tech hospital, our consultants’ skill sets are diverse, yet they share more similarities than differences in one area – passion for their field.

Over the coming months, I will be hosting a series of ‘Guest’ blogs authored by my colleague consultants within Blackrock Clinic. These blog posts will provide you with the expert opinion and experience of those who work day-to-day within their specialities, in the authentic voice they deserve.

I hope you will find the series as illuminating as I do. 

To begin the series, Dr Daniel O’Hare, Consultant Cardiologist and Electrophysiologist, presents his insights into the condition ‘Atrial Fibrillation’ and its treatment trajectory. Danny’s topic fits in neatly with the year in electrophysiology that Blackrock Clinic is having. The introduction of several novel technologies and the building of a brand new Cath Lab perhaps make 2022 our year of ‘EP’.”

James, CEO, Blackrock Clinic

Atrial Fibrillation: The past, present and future

Dr Daniel O’Hare

“Fibrillation of the auricle, is but one of a number of incidents that follow the inception of the new condition”

Sir James Mackenzie 1922
Dr Daniel O'Hare, Cardiologist & Electrophysiologist, Blackrock Clinic
Dr Daniel O’Hare, Cardiologist & Electrophysiologist, Blackrock Clinic

100 years ago Sir James Mackenzie wrote a review article in the British Medical Journal titled The Process which results in Auricular Fibrillation1. This describes how the recently discovered condition auricular fibrillation, later renamed atrial fibrillation (AF), is not an illness confined to the heart but rather one that leads to multiple downstream ill effects. The hope at the time was that understanding the mechanisms of AF would provide insight into the disruption of other organs and specifically the “abnormal states, that have hitherto baffled inquiry”.

Even in those early days there was a belief that any time spent in AF had a detrimental effect on both the heart itself and other systemic organs; a belief we now know to be true. The major therapeutic advancement of that year was the use of quinidine sulphate to restore sinus rhythm. However, in view of the prevailing lack of complete knowledge of the pharmacology2 it was soon discovered that use of this and other anti-arrhythmic medication was often associated with side-effects and sometimes even increased mortality3.

Electrical Cardioversion

It would be almost another 40 years (1959⁴) before the first use of electrical cardioversion in AF to restore sinus rhythm. This approach of electrically resetting the atria to sinus rhythm is still in common use today. However, other than transient atrial stunning post cardioversion5, the atrial conditions that led to the development of fibrillation remain unchanged. As a result, recurrence rates can be as high as 80% within a year.6

Catheter Ablation

A major breakthrough in treatment came in 19987, with the knowledge that atrial tissue often extends into the four pulmonary veins of the left atrium. It was discovered that catheter ablation at the entrance of these veins could prevent ectopic beats, arising here, from traversing into the body of the atrium to initiate the condition.

Radiofrequency & Cryothermal Ablation

iCLAS ultra-cold curvolinear catheter ablation system, Adagio Healthcare
iCLAS ultra-cold curvolinear catheter ablation system, Adagio Healthcare

The last 20 years have seen iterative improvements in radiofrequency and cryothermal ablation techniques. Blackrock Clinic has pioneered the latest treatment in both these fields, and earlier this year became the first hospital in Ireland to introduce Adagio’s latest iCLAS ultra-cold curvilinear catheter ablation.

New Advances

100 years on from Sir James Mackenzie’s article, it appears we are on the precipice of a breakthrough in treatment of AF.

The development of electroporation, or Pulse Field Ablation, offers a non-thermal ablation modality that uses ultrarapid electrical pulses to destabilise cell membranes. Pulse Field Ablation can therefore selectively ablate myocardial tissue (Figure 1), and reduce procedural related complications associated with ablation, including phrenic nerve, and oesophageal injury.

Figure 1. Before and after ablation using Pulse Field Electroporation. Electro-anatomical map of the left atrium demonstrating electrical isolation of the pullmonary veins. (Purple = healthy atrial tissue. Red = ablated tissue.

Blackrock Clinic is one of only a handful of centres in the UK and Ireland where this therapy is now available, and the clinical trials look extremely promising, especially when ablation is used in early stages.

Reducing outcomes such as: Stroke, Heart Failure & Death

The continual improvements in ablation technique and equipment now ensure pulmonary vein isolation can be performed more accurately and safer than ever before. We can now confirm catheter ablation’s superiority over anti-arrhythmic drug therapy at reducing AF burden and improving quality of life.

It is now the downstream adverse effects, or “incidents” as Sir James Mackenzie described them, that should be a focus of treatment, especially as there is mounting evidence associating AF with cognitive decline and dementia later in life.

Whilst appropriate anti-coagulation and comorbidity risk factor management remain the cornerstone of treatment for all patients, where it can be delivered safely, a rhythm control strategy must now be the goal for the new patient.

Targeting the restoration of sinus rhythm can reduce major cardiovascular outcomes such as:

  • Stroke,
  • Worsening heart failure, and
  • Death from cardiovascular causes.

Atrial Fibrillation and the Nation’s health

AF is a growing problem in Ireland, with approximately one in four European adults over the age of 55 predicted to develop the condition.8 Prevalence data from the Irish Longitudinal Study on Aging (TILDA)9 estimates the incidence of AF at 3.2% in Irish people over the age of 50, and using national population projections, this number is expected to increase 3-fold by 2040.10

To meet this future challenge, screening services such as Blackrock Clinic’s HealthCheck have been developed to help facilitate early detection and health optimisation against a comprehensive range of illnesses including cardiovascular diseases such as:

  • Hypertension,
  • Dyslipidaemia,
  • Obstructive sleep apnoea, and
  • Diabetes.

With the growing team of consultants specialising in all areas of cardiology, we have the expertise to offer the best possible care to our patients, including the latest interventions in our state-of-art catheterisation and electrophysiology labs.

Dr Daniel O’Hare is a consultant cardiologist and electrophysiologist working within Blackrock Clinic.

Full citation is available on request from the author.


1.           Mackenzie, J. Observations ON THE PROCESS WHICH RESULTS IN AURICULAR FIBRILLATION. BMJ 2, 71–73 (1922).


3.           Valembois, L. et al. Antiarrhythmics for maintaining sinus rhythm after cardioversion of atrial fibrillation. Cochrane database Syst. Rev. 9, CD005049 (2019).

4.           VISHNEVSKII, A. A., TSUKERMAN, B. M. & SMELOVSKII, S. I. [Control of fibrillating arrhythmia by the method of electrical defibrillation of the atrium]. Klin. Med. (Mosk). 37, 26–9 (1959).

5.           Fatkin, D., Kuchar, D. L., Thorburn, C. W. & Feneley, M. P. Transesophageal echocardiography before and during direct current cardioversion of atrial fibrillation: Evidence for “atrial stunning” as a mechanism of thromboembolic complications. J. Am. Coll. Cardiol. 23, 307–316 (1994).

6.           Van Gelder, I. C. & Crijns, H. J. Cardioversion of atrial fibrillation and subsequent maintenance of sinus rhythm. Pacing Clin. Electrophysiol. 20, 2675–83 (1997).

7.           Haïssaguerre, M. et al. Spontaneous Initiation of Atrial Fibrillation by Ectopic Beats Originating in the Pulmonary Veins. N. Engl. J. Med. 339, 659–666 (1998).

8.           Heeringa, J. et al. Prevalence, incidence and lifetime risk of atrial fibrillation: The Rotterdam study. Eur. Heart J. 27, 949–953 (2006).

9.           Finucane, C. et al. Low Awareness of Atrial Fibrillation in a Nationally Representative Sample of Older Adults. Circulation 124, A15661 (2011).

10.         Frewen, J. et al. Factors that influence awareness and treatment of atrial fibrillation in older adults. QJM 106, 415–24 (2013).