Implantable Loop Recorder Does Not Prevent Stroke in Older Patients With CVD

In patients with cardiovascular disease, implantable loop recorder screening for atrial fibrillation does not prevent stroke.

Implantable loop recorder (ILR) screening does not prevent stroke among older patients with cardiovascular disease (CVD), according to results of a post-hoc analysis published in the International Journal of Cardiology.

The LOOP study recruited patients without atrial fibrillation (AF) who were aged 70 to 90 years with (n=1997) and without (n=4007) CVD at 4 centers in Denmark between 2014 and 2016. Participants were randomly assigned in a 1:3 ratio to receive ILR monitoring or usual care. For participants in the ILR monitoring group, oral anticoagulation therapy was initiated following new-onset AF lasting 6 minutes or longer. The efficacy of ILR monitoring for preventing stroke and systemic arterial embolism was evaluated.

The populations with and without CVD comprised 64.8% and 46.7% men (P <.001), mean age was 75.0 (SD, 4.3) and 74.6 (SD, 4.0) years (P <.001), and BMIs were 27.4 (SD, 4.3) and 27.8 (SD, 4.7; P <.001), respectively. Compared with the cohort without CVD, the cohort with CVD smoked more; had lower blood pressure and heart rate; had higher CH2DS2-VASc score; fewer had hypertension and diabetes; fewer used calcium channel blockers, thiazide diuretics, and antidiabetic drugs; and more used beta-blockers mineralocorticoid receptor antagonists, digoxin renin-angiotensin inhibitors, loop diuretics, platelet inhibitors, and statins (all P ≤.004).

Among the participants with CVD, 130 had a stroke and 2 had a systemic arterial embolism during follow-up. Among the participants without CVD, 185 had a stroke and 1 had a systemic arterial embolism during follow-up, corresponding with composite incidence rates of 1.32 and 0.90 per 100 person-years.

…ILR screening did not prevent stroke significantly in individuals with CVD, whereas screening was associated with approximately 40% stroke risk reduction among those without CVD.

Overall, CVD was associated with increased risk for all-cause mortality (adjusted hazard ratio [aHR], 1.59; 95% CI, 1.36-1.85); stroke, systemic arterial embolism, and cardiovascular death (aHR, 1.49; 95% CI, 1.23-1.79); stroke and systemic arterial embolism (aHR], 1.34; 95% CI, 1.06-1.69); and ischemic stroke (aHR, 1.31; 95% CI, 1.02-1.69) comapred with patients without CVD.

Incident AF events occurred among 28.7% of the ILR cohort and 11.2% of the control patients for the no preexisting CVD group and among 37.9% of the ILR cohort and 14.2% of the control patients for the CVD group.

In general, CVD was associated with incident AF for both the ILR (aHR, 1.32; 95% CI, 1.09-1.59) and control (aHR, 1.24; 95% CI, 1.03-1.48) cohorts compared with patients without CVD and ILR was not associated with AF prevention compared with usual care (aHR, 1.13; 95% CI, 0.76-1.68). When patients with CVD were stratified by etiology at baseline, ILR screening was associated with reduced risk for stroke and systemic arterial embolism among the subset of patients who did not have stroke, ischemic heart disease, or peripheral artery disease at baseline (aHR, 0.62; 95% CI, 0.43-0.90).

For the cohort without CVD at baseline, ILR screening was associated with lower risk for stroke and systemic arterial embolism (aHR, 0.64; 95% CI, 0.44-0.93); stroke, systemic arterial embolism, and cardiovascular death (aHR, 0.64; 95% CI, 0.46-0.87); and ischemic stroke (aHR, 0.54; 95% CI, 0.35-0.82).

The findings of this study may have been biased by only considering CVD at baseline and not incident CVD.

“…ILR screening did not prevent stroke significantly in individuals with CVD, whereas screening was associated with approximately 40% stroke risk reduction among those without CVD,” the study authors wrote. “However, these findings should be considered as hypothesis-generating and warrant further study.”

Disclosure: Multiple authors declared affiliations with industry. Please refer to the original article for a full list of disclosures.

References:

Xing LY, Diederichsen SZ, Højberg S, et al. Screening for atrial fibrillation to prevent stroke in elderly individuals with or without preexisting cardiovascular disease: a post hoc analysis of the randomized LOOP Study. Int J Cardiol. Published online October 31, 2022. doi:10.1016/j.ijcard.2022.10.167