Ever sit around telling spooky ghost stories about the thumping of a beating heart which grows louder and louder and LOUDER until all the children run away shrieking? A recent study published in JAMA Cardiology about the prognostic significance of bradyarrhythmias has a similar effect.
The article is a hard one to get through, but the TLDR version (‘too long, didn’t read’ for all of you reading this who are now one step closer to understanding ‘the kids these days’) is actually quite simple: while bradyarrhythmias in older adults may themselves be a risk factor for death, diagnosing and treating them doesn’t help avert it.
This was a post-hoc analysis of the LOOP trial previously summarized in an EBM Focus in which 6,004 adults age 70 or older with hypertension, diabetes, heart failure, or previous stroke were randomized to receive either an implantable loop recorder or usual care. The results of that original trial demonstrated a three-fold increase in the diagnosis of atrial fibrillation and initiation of anticoagulation, with no significant reduction in stroke incidence. Points off for self-selected recruitment by responding to a letter and for lack of blinding in that trial.
For any screening intervention to be worthwhile, early detection needs to lead to better outcomes than waiting for symptoms to manifest.
For any screening intervention to be worthwhile, early detection needs to lead to better outcomes than waiting for symptoms to manifest.
The scene of the current study is just as dismal, which, as any good post-hoc analysis does, evaluated a dizzying number of non-prespecified outcomes through many analyses which we will not get into here. (You’re welcome.) The most important outcomes were that screening using the implantable loop recorder resulted in a six-fold increase in the detection of mostly asymptomatic bradyarrhythmias and a significant increase in pacemaker implantations compared with usual care, but with no difference in the risk of syncope or sudden death, even in people with high-grade symptomatic arrhythmias.
So where does this leave us in a world of constantly increasing digital input and the need to know more and do more about it? We have to remember that for any screening intervention to be worthwhile, early detection needs to lead to better outcomes than waiting for symptoms to manifest. Otherwise, we are treating people for no benefit and exposing them to harms. Scarily, this tell-tale story of overdiagnosis and overtreatment ends with the thumping sounds of paced heartbeats coming from the strange bumps on the chests of the very many older people who won’t benefit from this intervention. Either that or the thumping sound is coming from inside the house… driven by our own anxiety related to not acting on a hair-raising diagnosis.
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Practice Point: More screening for bradyarrhythmias leads to a lot more diagnoses, a lot more pacemakers, and no difference in syncope or sudden cardiac death.
EBM Pearl: While threats to validity like lack of blinding, self-selected recruitment, and post-hoc analyses tend to overestimate the magnitude of effect in favor of the intervention, we don’t have to worry as much about this when no difference is found in the primary outcome.
Reference: JAMA Cardiol. 2023 Feb 15
For more information, see the topic Atrial Fibrillation in DynaMed.
