Prediction of postoperative atrial fibrillation with postoperative epicardial electrograms

Objectives. New-onset postoperative atrial fibrillation (POAF) is a common complication after cardiac surgery. The arrhythmia often entails a longer hospital stay, greater risk of other complications, and higher mortality both short- and long-term. An investigation of the use of early atrial electrograms in predicting POAF in cardiac surgery was performed. Design. In this prospective observational study, a total of 99 consecutive adult patients undergoing coronary artery bypass grafting, valve surgery or both were included. On the first postoperative morning, standard 12-lead electrograms (ECG), unipolar atrial electrograms (aEG), and vital values were recorded. The outcome was new-onset POAF within one month postoperatively. Results. Three multivariable prediction models for POAF were formed using measurements derived from the ECG, aEG, and patient characteristics. Age, body mass index, and two unipolar electrogram measurements quantifying local activation time and fractionation were strongly associated with the outcome POAF. The performance of the POAF prediction models was assessed through receiver operating curve characteristics with cross-validation, and discrimination using the leave-one-out-method to internally validate the models. The cross-validated area under the receiver operating characteristic curve (AUC) was improved in a prediction model using atrial-derived electrogram variables (AUC 0.796, 95% CI 0.698-0.894), compared with previous ECG and clinical models (AUC 0.716, 95% CI 0.606-0.826 and AUC 0.718, 95% CI 0.613-0.822, respectively). Conclusions. This study found that easily obtainable measurements from atrial electrograms may be helpful in identifying patients at risk of POAF in cardiac surgery

Osborn waves following out-of-hospital cardiac arrest:Effect of level of temperature management and risk of arrhythmia and death

Background: The Osborn or J-wave, an upright deflection of the J-point on the electrocardiogram (ECG), is often observed during severe hypothermia. A possible relation between Osborn waves (OW) and increased risk of ventricular arrhythmia has been reported. We sought to determine whether the level of targeted temperature management (TTM) following out-of-hospital cardiac arrest (OHCA) affects the prevalence of OW and to assess the associations between OW and risk of ventricular arrhythmia and death. Methods and results: The present study is part of the TTM-trial ECG-substudy (including OHCA-patients randomized to TTM at 33 °C vs. 36 °C from 24 of 36 sites). Serial 12-lead ECGs from 680 (94%) patients were analysed and stratified by OW at predefined time-points (0, 4, 28, 36, 72-h after admission). On admission, the overall prevalence of OW was 16%, increasing to 32% at target temperature, with higher prevalence in the 33 °C-group (40% vs. 23%, p < 0.0001). No difference in prevalence was found between the 33 °C- and 36 °C-groups on admission (18% vs. 14%, p =.11) or after rewarming (13% vs. 10%, p =.44). OW were not associated with increased risk of ventricular arrhythmia (Odds ratio = 0.78 (0.51–1.20), p =.26), but associated with significantly lower 180-day mortality as compared to no OW (38% vs. 52%, plog-rank = 0.001) in univariable analyses only. Conclusion: OW are frequent during TTM, particularly in patients treated with 33 °C. OW are not associated with increased risk of ventricular arrhythmia, and may be considered a benign physiological phenomenon, associated with lower mortality in univariable analyses

Systolic Blood Pressure and Effects of Screening for Atrial Fibrillation With Long-Term Continuous Monitoring (a LOOP Substudy)

BACKGROUND: Hypertension is a well-known risk factor for atrial fibrillation (AF) and stoke, but data on the interaction between systolic blood pressure (SBP) and effects of AF screening are lacking. METHODS: The LOOP Study randomized AF-naïve individuals aged 70 to 90 years with additional stroke risk factors to either screening with implantable loop recorder (ILR) and anticoagulation initiation upon detection of AF episodes ≥6 minutes, or usual care. In total, 5997 participants with available baseline SBP measurements were included in this substudy. Outcomes were analyzed according to the time-to-first-event principle using cause-specific Cox models. RESULTS: The hazard ratio of stroke or systemic arterial embolism for ILR versus control decreased with increasing SBP. ILR screening yielded a 44% risk reduction of stroke or systemic arterial embolism among participants with SBP ≥150 mm Hg (adjusted hazard ratio, 0.56 [0.37–0.83]). Within the ILR group, SBP≥150 mm Hg was associated with a higher incidence of AF episodes ≥24 hours than lower SBP (adjusted hazard ratio, 1.70 [1.08–2.69]) but not with the overall occurrence of AF (adjusted P>0.05). CONCLUSIONS: The impact of AF screening on thromboembolic events increased with increasing blood pressure. SBP≥150 mm Hg was associated with a >1.5-fold increased risk of AF episodes ≥24 hours, along with an almost 50% risk reduction of stroke or systemic arterial embolism by ILR screening compared to lower blood pressure. These findings should be considered hypothesis-generating and warrant further study. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique Identifier: NCT02036450

Severity and Etiology of Incident Stroke in Patients Screened for Atrial Fibrillation vs Usual Care and the Impact of Prior Stroke:A Post Hoc Analysis of the LOOP Randomized Clinical Trial

IMPORTANCE: Atrial fibrillation (AF) screening trials have failed to demonstrate a significant reduction in stroke risk. The impact on stroke severity and the importance of prior strokes are unknown. OBJECTIVE: To assess stroke characteristics in patients undergoing implantable loop recorder (ILR) screening for AF vs usual care and assess the importance of prior stroke. DESIGN, SETTING, AND PARTICIPANTS: This was a post hoc analysis of the Atrial Fibrillation Detected by Continuous Electrocardiogram Monitoring Using Implantable Loop Recorder to Prevent Stroke in High-Risk Individuals (LOOP) randomized clinical trial. Persons 70 years or older without known AF but diagnosed with 1 or more of the following, hypertension, diabetes, heart failure, or prior stroke, were screened for inclusion. Four sites in Denmark recruited participants by letter between January 31, 2014, and May 17, 2016. The median (IQR) follow-up period was 65 (59-70) months. Data were analyzed from April 1 to May 31, 2022. INTERVENTIONS: ILR screening for AF and anticoagulation initiation if AF duration of 6 minutes or longer was detected (ILR group) vs usual care (control group). MAIN OUTCOMES AND MEASURES: Adjudicated stroke, classified according to the modified Rankin Scale (mRS) using a score of 3 or more as a cutoff for severe (disabling or lethal) stroke, and according to the Trial of Org 10172 in Acute Stroke Treatment (TOAST) classification for ischemic strokes. RESULTS: A total of 6205 individuals were screened for inclusion, and 6004 were randomized and included in the analysis; 4503 participants (75%; mean [SD] age, 74.7 [4.1] years; 2375 male [52.7%]) were assigned to the control group and 1501 participants (25%; mean [SD] age, 74.7 [4.1] years; 792 male [52.8%]) were assigned to the ILR group. A total of 794 of 4503 participants (17.6%) in the control group had a history of prior stroke compared with 262 of 1501 participants (17.5%) in the ILR group. During follow-up, AF was diagnosed in 1027 participants (control group, 550 [12%] vs ILR group, 477 [32%]), and anticoagulation was initiated in 89% of these (910). A total of 315 participants (5.2%) had a stroke (control group, 249 [5.5%] vs ILR group, 66 [4.4%]), and the median (IQR) mRS score was 2 (1-3) with no difference across the groups. A total of 272 participants (4.5%) had ischemic stroke (control group, 217 [4.8%] vs ILR group, 55 [3.7%]), and 123 (2.0%) had severe stroke (control group, 100 [2.2%] vs ILR group, 23 [1.5%]), and the hazard ratios comparing the control and ILR groups were 0.76 (95% CI, 0.57-1.03; P = .07) and 0.69 (95% CI, 0.44-1.09; P = .11), respectively. For participants without prior stroke, the hazard ratios were 0.68 (95% CI, 0.48-0.97; P = .04) and 0.54 (95% CI, 0.30-0.97; P = .04), respectively. CONCLUSIONS AND RELEVANCE: This post hoc analysis of the LOOP randomized clinical trial found that ILR screening for AF did not result in a significant decrease in ischemic or severe strokes compared with usual care. Exploratory subgroup analyses indicated a possible reduction of these outcomes among participants without prior stroke. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT0203645