Recurrence of new-onset post-operative AF after cardiac surgery: detected by implantable loop recorders: A systematic review and Meta-analysis

BACKGROUND

Atrial fibrillation (AF) is one of the most common complications after cardiac surgery. New-onset post-operative AF may signal an elevated risk of AF and associated outcomes in long-term follow-up. We aimed to estimate the rate of AF recurrence as detected by an implantable loop recorder (ILR) in patients experiencing post-operative AF within 30 days after cardiac surgery.

METHODS

We searched MEDLINE, Embase and Cochrane CENTRAL to April 2023 for studies of adults who did not have known AF, experienced new-onset AF within 30 days of cardiac surgery and received an ILR. We pooled individual participant data on timing of AF recurrence using a random-effects model with a frailty model applied to a Cox proportional hazard analysis.

RESULTS

From 8671 citations, 8 single-centre prospective cohort studies met eligibility criteria. Data were available from 185 participants in 7 studies, with a median follow-up of 1.7 (IQR: 1.3-2.8) years. All included studies were at a low risk of bias. Pooled AF recurrence rates following 30 post-operative days were 17.8% (95% CI 11.9%-23.2%) at 3 months, 24.4% (17.7%-30.6%) at 6 months, 30.1% (22.8%-36.7%) at 12 months and 35.3% (27.6%-42.2%) at 18 months.

CONCLUSIONS

In patients who experience new-onset post-operative AF after cardiac surgery, AF recurrence lasting at least 30 s occurs in approximately 1 in 3 in the first year after surgery. The optimal frequency and modality to use for monitoring for AF recurrence in this population remain uncertain.

Dual-chamber paced patients without high-degree AV block at baseline are at higher risk of atrial arrhythmias when inappropriately paced in the right ventricle: a sub-analysis of the EMERALD study

Background/Introduction

Unnecessary right ventricular pacing (RVP) can have deleterious effects including an increased risk of atrial arrhythmia (AA) and heart failure during follow-up (FU) in dual-chamber (DR) paced patients. While previous studies have shown that these increased risks occur with RVP>40%, the EMERALD Study demonstrated an increased risk for RVP>1%. Few data exist on the interaction between the amount of RVP and the presence/absence of high-degree atrio-ventricular block (AVB) as a pacing indication at baseline.

Purpose

The EMERALD (AssEssment of CoMorbiditiEs & Atrial ArRhythmiA Burden In DuaL-Chamber PaceD Patients) Study was a real-world registry designed to assess the impact of RVP burden on the risk of developing persistent/permanent AA (Pers-AA) over 2-year FU. The primary endpoint was the difference in Pers-AA in subjects with high (>40%) and low (<40%) RVP. This sub-analysis aimed to identify the interaction between RVP and the presence/absence of high-degree AVB at baseline in relation to the incidence of Pers-AA.

Methods

EMERALD was a non-interventional, prospective, multi-center registry conducted at 186 centers in 12 countries. Enrolled subjects were implanted with a DR pacemaker according to ESC or ACC/AHA/HRS guidelines. Subjects were excluded if they had a history of Pers-AA. Devices could be implanted as de-novo, replacement or upgrade therapy. Programming was left to the investigators' discretion. Subjects were followed for at least 24 months. Pers-AA was defined as: >22 h/day of AA for >7 consecutive days; Pers-AA diagnosed during any FU visit; AA-related ablation or cardioversion carried out in the FU period. We compared the incidence of Pers-AA between subjects with (n=1529) and without (n=1948) high-degree AVB as a baseline pacing indication.

Results

Eligible FU data were available for n=3477 subjects. The overall population was nearly evenly split - High RVP (47.7%) and Low RVP (52.3%). In the High RVP group, 11.7% experienced at least one Pers-AA episode versus 9.1% in the Low RVP group (p=0.006). In this sub-analysis, the prevalence of RVP>40% was higher in patients with high-degree AVB at baseline (74% vs 26%). Although the incidence of Pers-AA was similar in the group with high-degree AVB at baseline (High RVP 8.7% vs Low RVP 7.4%), in the group without high-degree AVB at baseline, those with High RVP developed a significantly higher incidence of Pers-AA (High RVP 18.2% vs Low RVP 9.5%, p value for interaction 0.0275; Figure 1). An analysis with a newly identified RVP threshold of 1% confirmed a high incidence of Pers-AA only in the group without high-degree AVB at baseline (18% vs 3.5%, p value for interaction 0.2265; Figure 2).

Conclusions

The baseline pacing indication sub-analysis of the EMERALD Study shows that patients without high-degree AVB as a baseline indication are at highest risk of Pers-AA. Efforts should be made to avoid any unnecessary RVP in this subgroup of patients.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): MicroPort CRM (Clamart, France)

Radiographic Predictors of Lead Conductor Fracture

Background—

Lead fracture is a limiting factor in high voltage lead durability. Fractures noted with the Medtronic Fidelis leads provide an opportunity to examine factors captured on implant chest x-ray that correlate with risk for lead conductor fracture. We evaluated contributory factors in a large population of fractures.

Methods and Results—

We conducted a retrospective case–control study at 8 Canadian centers that routinely capture anterior posterior and lateral chest x-rays within 2 weeks of implant. Cases were patients that experienced confirmed Medtronic Fidelis 6949 lead fracture based on standard definitions, matched one-to-one to controls for date of implant, sex, and age with normally functioning Fidelis leads from the same center. Select chart data and x-rays were collected for all patients. Radiographic measurements by ≥2 individuals per case/control were blinded to patient status. The data were analyzed using a time to failure multivariable Cox proportional hazards model with stratification for each matched pair. X-ray pairs from 111 fracture patients were compared with 111 controls (age 61.5±12.8 years, 75% male, 221 model 6949 leads). Six parameters included in the statistical analysis were significantly associated with risk of fracture, including slack/tortuosity measures, pulse generator and superior vena cava coil location, and angle of lead exit from the pocket.

Conclusions—

Pocket, intravascular and intracardiac lead characteristics on x-ray correlate with risk of lead conductor fracture. These observations may be useful to direct implant technique to optimize lead durability. Validation in larger populations and other lead models may inform the application of these results.

Short-term streptozotocin-induced diabetes induces blood pressure decrease associated with reduced aortic (45)Ca(2+) uptake and selective depression of the sustained noradrenergic contraction

To test the hypothesis that diabetes can selectively affect the intracellular and extracellular components of the noradrenergic vascular response in rats, we studied changes in blood pressure, in vitro vascular contraction and (45) Ca(2+) uptake in experimental diabetes induced by injection of 60 mg/kg of streptozotocin (STZ). One week after induction of diabetes mean blood pressure decreased significantly from 106 +/- 3 mmHg to 89 +/- 2 mmHg. After incubation in Ca(2+) =1.6 mM, contraction of STZ aortic rings to 10(- 7) M of norepinephrine was preserved in its intracellular component (Control: 231 +/- 28, STZ: 274 +/- 22 mgForce/mgTissue, NS) but depressed in its extracellular component (Control: 277 +/- 24, STZ: 133 +/- 33 mgForce/mgTissue, P<0.05). Uptake of (45) Ca(2+) in the same rings was depressed in both components. Norepinephrine contractions due to extracellular Ca(2+) (prior depletion of norepinephrine-sensitive Ca(2+) stores) unexpectedly exhibited a initial component whose magnitude in control rings was similar to the response due to intracellular Ca(2+) (extra: 503 +/- 65 mg, intra: 411 +/- 30 mgForce/mgTissue), and was not depressed in STZ preparations (399 +/- 62 mgForce/mgTissue). The sustained contraction to norepinephrine in extracellular Ca(2+) was significantly reduced in STZ aortas (1163 +/- 92 vs. 528 +/- 95 mgForce/mgTissue). We conclude that: 1) Short-term streptozotocin-induced diabetes features reduced blood pressure along with deficient aortic (45) Ca uptake and contraction to norepinephrine, and 2) Only the sustained phase of the norepinephrine contraction, dependent on extracellular Ca(2+), was depressed in the diabetic rats and could possibly be associated with the observed fall in blood pressure.