Despite more than a decade of intensified clinical research, our knowledge about atrial fibrillation (AF) is still far from satisfactory, and particularly the optimal treatment remains unclear. In fact, even the very basic question if attempts should be made to convert AF into sinus rhythm and to maintain it, or to simply limit the ventricular rate by drugs that slow atrioventricular conduction (and which strategy in whom?) is not yet answered satisfactory.
Results of the AFFIRM1 and AF-CHF2 trials were disappointing to a high degree showing no advantage of trying to maintain sinus rhythm or even a trend towards a higher mortality for ‘rhythm control’. This leads to the misinterpretation that AF seems to be harmless even in the context of heart failure. To avoid this, it should be pointed out that a post hoc analysis of the AFFIRM trial demonstrated that patients who were in sinus rhythm (no matter to which treatment group they were allocated) had a better prognosis than patients in AF.3 That may indicate that in AFFIRM and AF-CHF, the treatment applied to maintain sinus rhythm was much less successful than expected. In AFFIRM, the finding that stroke was more frequent during ‘rhythm control’ is likely explained by a significant number of patients with undetected AF not receiving oral anticoagulation.1,3 Studies on anti-arrhythmic drugs showed that ∼70% of AF episodes are not noticed by the patients.4 Therefore, studies relying on infrequent electrocardiogram recording may severely underestimate the AF recurrence rate and overestimate the success of anti-arrhythmic drugs. Using pacemaker memory with stored atrial electrograms as a continuous monitor, AF recurrences were detected over 18 months in 88% of patients, seemingly in successful rhythm control by optimized anti-arrhythmic drugs.5 This may explain some of the disappointing results from large AF trials: the efficacy of anti-arrhythmic drugs in the rhythm control is not well known, AF recurrences are not detected or only with delay, and important therapeutic interventions (change of an ineffective drug regimen, oral anticoagulation) are not performed or only after a significant time lag.
In this context, the present study by Ricci et al.6 is of particular interest. In 42 of 166 patients, AF was detected by implanted pacemakers or ICDs during the course of 18 months. Only clinically relevant AF detections (first detected or persistent AF, AF for >10% of the time during at least five consecutive days) were regarded. Of note, AF was not known before device implantation in more than half of these patients. Confirming previous observations, 73% of AF episodes were completely asymptomatic and not perceived by patients. Through remote monitoring technology, AF detection was immediately transmitted to the institution which followed the patient. Thus, AF detection occurred much earlier than with routine follow-up, enabling the treating physician to start therapeutic interventions such as anticoagulation, anti-arrhythmic drug modification, or cardioversion on average 148 days earlier.
This study can only verify the feasibility of device remote monitoring for AF management and is certainly not intended to assess the clinical benefits of this technology in terms of reduction of stroke, hospitalizations, or mortality. However, it may provide an interesting perspective on the utility of remote monitoring of implantable devices in rhythm control strategies in patients with AF. It may facilitate the detection of anti-arrhythmic drug treatment failure enabling either an early modification of the drug dose, substance, or class. It may also aid in detecting pro-arrhythmic effects or in deciding to discontinue unsuccessful pharmacological attempts of rhythm control and proceed to catheter ablation or rate control. Potentially, early detection of AF recurrences may also prevent atrial electrical remodelling and improve sinus rhythm maintenance after cardioversion.
It is of particular interest if device detection of AF with remote monitoring may change anticoagulation strategies. Despite the fact that anticoagulation has been shown to significantly improve the outcome in patients with AF in numerous studies, it is associated with potentially life-threatening side effects and is therefore not well accepted among many physicians and patients.7 Automatic AF detection with patient and/or physician alerting functions may enable a ‘needle in the pocket’ approach to anticoagulation where the patient does not receive permanent warfarin or similar but (e.g.) low molecular weight heparin only whenever AF is detected by the device.
The present observational study by Ricci et al. cautiously implies the potential of remote monitoring of implanted devices in the management of AF. It may encourage further investigation in the optimal treatment of AF where several important issues remain unsolved.
Conflict of interest: C.W.I. is currently conducting research sponsored by Medtronic Inc. and St. Jude Medical. He is a member of the speaker's bureaus of Medtronic and St. Jude Medical, and of the advisory boards of Medtronic and Sorin.
The opinions expressed in this article are not necessarily those of the Editors of Europace or of the European Society of Cardiology.
; Atrial Fibrillation Follow-up Investigation of Rhythm Management (AFFIRM) Investigators. A comparison of rate control and rhythm control in patients with atrial fibrillation. N Engl J Med 2002;347:1825-33.
; AFFIRM Investigators. Relationships between sinus rhythm, treatment, and survival in the Atrial Fibrillation Follow-Up Investigation of Rhythm Management (AFFIRM) Study. Circulation 2004;109:1509-13.