Implantable loop recorder helps prevent strokes in older adults without CVD

The use of an implantable loop recorder (ILR) device can help reduce stroke incidence in individuals without cardiovascular diseases (CVD), according to a recent study. However, screening with such device appears to have limited benefit in those with CVDs.

“Continuous AF screening did not prevent stroke significantly in individuals with pre-existing CVD, whereas screening was associated with an approximately 40-percent stroke risk reduction in those without CVD. These findings should be considered as hypothesis-generating and warrant further study,” the researchers said.

Of the 6,004 study participants enrolled, majority (66.7 percent; n=4,007) were free of CVDs at baseline, while 33.3 percent (n=1,997) had at least one CVD event before, of which stroke was the most common. All participants had no history of atrial fibrillation (AF). [Int J Cardiol 2022;doi:10.1016/j.ijcard.2022.10.167]

Stroke or systemic arterial embolism (SAE), the primary outcome, occurred in 132 participants with prior CVD and in 186 without such a history. The resulting event rates were 1.32 (95 percent confidence interval [CI], 1.11–1.57) and 0.90 (95 percent CI, 0.78–1.04) per 100 person-years, respectively.

Of note, the risk difference between the two groups was statistically significant, indicating that strokes and SAEs were significantly more likely to occur among those who had a history of CVD (adjusted hazard ratio [HR], 1.34, 95 percent CI, 1.06–1.69).

CVD history likewise aggravated the risk of secondary outcomes, such as ischaemic stroke (adjusted HR, 1.31, 95 percent CI, 1.02–1.69), all-cause death (adjusted HR, 1.59, 95 percent CI, 1.36–1.85), and a composite of stroke, SAE, and cardiovascular death (adjusted HR, 1.49, 95 percent CI, 1.23–1.79).

CVD history

Since CVD history affected the likelihood of the primary outcome occurring, researchers hypothesized that it might also influence the ability of long-term AF screening with the ILR device to predict strokes.

Indeed, their analysis revealed that ILR screening was significantly effective at preventing strokes and SAEs in those without a history of CVD. In these participants, the resulting event rate was 0.64 (95 percent CI, 0.44–0.90) per 100 person-years, as opposed to 0.99 (95 percent CI, 0.84–1.16) per 100 person-years in those who received usual care.

The resulting risk estimate was statistically significant, indicating better event prevention among those with the device implant (adjusted HR, 0.64, 95 percent CI, 0.44–0.93).

However, ILR screening was not significantly effective among those with a history of CVD, in whom the risk of stroke and SAE remained comparable to those who underwent usual care (adjusted HR, 1.13, 95 percent CI, 0.76–1.68).

“It could be speculated that high-level patient care and monitoring due to established CVD might already have been able to detect those most clinically relevant AF,” the researchers said, which is “why ILR screening did not appear to contribute to additional stroke prevention in this patient population.”

Important study limitations include its post hoc nature and the potential misclassification bias for patients who acquired CVD during follow-up.