A single-beat algorithm to discriminate farfield from nearfield bipolar voltage electrograms from the pulmonary veins.

BACKGROUND Superimposition of farfield (FF) and nearfield (NF) bipolar voltage electrograms (BVE) complicates the confirmation of pulmonary vein (PV) isolation after catheter ablation of atrial fibrillation. Our aim was to develop an automatic algorithm based on a single-beat analysis to discriminate PV NF from atrial FF BVE from a circular mapping catheter during the cryoballoon PV isolation. METHODS During freezing cycles in cryoablation PVI, local NF and distant FF signals were recorded, identified and labelled. BVEs were classified using four different machine learning algorithms based on four frequency domain (high-frequency power (PHF), low-frequency power (PLF), relative high power band, PHF ratio of neighbouring electrodes) and two time domain features (amplitude (Vmax), slew rate). The algorithm-based classification was compared to the true identification gained during the PVI and to a classification by cardiac electrophysiologists. RESULTS We included 335 BVEs from 57 consecutive patients. Using a single feature, PHF with a cut-off at 150 Hz showed the best overall accuracy for classification (79.4%). By combining PHF with Vmax, overall accuracy was improved to 82.7% with a specificity of 89% and a sensitivity of 77%. The overall accuracy was highest for the right inferior PV (96.6%) and lowest for the left superior PV (76.9%). The algorithm showed comparable accuracy to the classification by the EP specialists. CONCLUSIONS An automated farfield-nearfield discrimination based on two simple features from a single-beat BVE is feasible with a high specificity and comparable accuracy to the assessment by experienced cardiac electrophysiologists

Complement activation products in acute heart failure: Potential role in pathophysiology, responses to treatment and impacts on long-term survival

Previous studies have indicated a correlation between heart failure, inflammation and poorer outcome. However, the pathogenesis and role of inflammation in acute heart failure (AHF) is incompletely studied and understood. The aim of our study was to explore the potential role of innate immunity - quantified by complement activation products (CAPs) - in pathophysiology, responses to treatment and impacts on long-term survival in AHF.; In a prospective study enrolling 179 unselected patients with AHF, plasma concentrations of C4d, C3a and sC5b-9 were measured in a blinded fashion on the first day of hospitalisation and prior to discharge. The final diagnosis, including the AHF phenotype, was adjudicated by two independent cardiologists. Long-term follow-up was obtained. Findings in AHF were compared to that obtained in 75 healthy blood donors (control group).; Overall, concentrations of all three CAPs were significantly higher in patients with AHF than in healthy controls (all p < 0.001). In an age-adjusted subgroup analysis, significant differences could be confirmed for concentrations of C4d and sC5b-9, and these parameters further increased after 6 days of in-hospital treatment ( p < 0.001). In contrast, C3a levels in AHF patients did not differ from those of the control group in the age-adjusted subgroup analysis and remained constant during hospitalisation. Concentrations of C4d, C3a and sC5b-9 were significantly higher when AHF was triggered by an infection as compared to other triggers ( p < 0.001). In addition, CAP levels significantly correlated with each other ( r = 0.64-0.76), but did not predict death within 2 years.; Activation of complement with increased plasma levels of C4d and sC5b-9 at admission and increasing levels during AHF treatment seems to be associated with AHF, particularly when AHF was triggered by an infection. However, CAPs do not have a prognostic value in AHF

Sex-related electrocardiographic differences in patients with different types of atrial fibrillation: Results from the SWISS-AF study.

BACKGROUND Sex-related electrocardiographic differences are a well-known phenomenon, but not their expression in patients with atrial fibrillation (AF). In this study we aim to assess the presence of significant sex-related differences in ECG features, with particular attention to P-wave parameters, of a large cohort of patients affected by different types of AF. METHODS A 5-min resting 16-lead ECG was evaluated for 1119 AF patients in sinus rhythm. The durations of the main ECG waves and intervals were measured for both atrial and ventricular activity. Moreover, the beat-to-beat P-wave variability was computed for lead II and for the first principal component (PC1) computed across the 16 leads. The percentage of variance explained by PC1 was computed. RESULTS Males compared to females showed significantly longer RR interval (1.02 ± 0.16 s vs 0.97 ± 0.15 s, p < .001), PQ interval (191 ± 34 ms vs 183 ± 35 ms, p = .008), QRS duration (105 ± 17 ms vs 98 ± 13 ms, p = .021), significantly lower percentage of variance explained by PC1 and P-wave variability. Males with paroxysmal AF compared to females with paroxysmal AF had significantly longer RR interval (1.01 ± 0.17 s vs 0.96 ± 0.14 s, p < .001), shorter QTc (388 ± 27 ms vs 402 ± 27 ms, p < .001), lower P-wave variability in PC1. Males with persistent AF compared to females with persistent AF had significantly shorter QTc interval (396 ± 30 ms vs 407 ± 26 ms, p = .019), longer PQ interval (194 ± 35 ms vs 182 ± 30 ms, p = .037), higher V1 terminal force (2.1 ± 1.2 mV*ms vs 1.8 ± 1 mV*ms, p = .007), lower percentage of variance explained by PC1. CONCLUSIONS AF patients present with several sex-related ECG differences. Consequently, sex should be taken into account when developing ECG algorithms identifying patients at risk for AF progression

A single-beat algorithm to discriminate farfield from nearfield bipolar voltage electrograms from the pulmonary veins.

Superimposition of farfield (FF) and nearfield (NF) bipolar voltage electrograms (BVE) complicates the confirmation of pulmonary vein (PV) isolation after catheter ablation of atrial fibrillation. Our aim was to develop an automatic algorithm based on a single-beat analysis to discriminate PV NF from atrial FF BVE from a circular mapping catheter during the cryoballoon PV isolation. During freezing cycles in cryoablation PVI, local NF and distant FF signals were recorded, identified and labelled. BVEs were classified using four different machine learning algorithms based on four frequency domain (high-frequency power (P &lt;sub&gt;HF&lt;/sub&gt; ), low-frequency power (P &lt;sub&gt;LF&lt;/sub&gt; ), relative high power band, P &lt;sub&gt;HF&lt;/sub&gt; ratio of neighbouring electrodes) and two time domain features (amplitude (V &lt;sub&gt;max&lt;/sub&gt; ), slew rate). The algorithm-based classification was compared to the true identification gained during the PVI and to a classification by cardiac electrophysiologists. We included 335 BVEs from 57 consecutive patients. Using a single feature, P &lt;sub&gt;HF&lt;/sub&gt; with a cut-off at 150 Hz showed the best overall accuracy for classification (79.4%). By combining P &lt;sub&gt;HF&lt;/sub&gt; with V &lt;sub&gt;max&lt;/sub&gt; , overall accuracy was improved to 82.7% with a specificity of 89% and a sensitivity of 77%. The overall accuracy was highest for the right inferior PV (96.6%) and lowest for the left superior PV (76.9%). The algorithm showed comparable accuracy to the classification by the EP specialists. An automated farfield-nearfield discrimination based on two simple features from a single-beat BVE is feasible with a high specificity and comparable accuracy to the assessment by experienced cardiac electrophysiologists

Heart Rate Variability Triangular Index as a Predictor of Cardiovascular Mortality in Patients With Atrial Fibrillation.

Background Impaired heart rate variability (HRV) is associated with increased mortality in sinus rhythm. However, HRV has not been systematically assessed in patients with atrial fibrillation (AF). We hypothesized that parameters of HRV may be predictive of cardiovascular death in patients with AF. Methods and Results From the multicenter prospective Swiss-AF (Swiss Atrial Fibrillation) Cohort Study, we enrolled 1922 patients who were in sinus rhythm or AF. Resting ECG recordings of 5-minute duration were obtained at baseline. Standard parameters of HRV (HRV triangular index, SD of the normal-to-normal intervals, square root of the mean squared differences of successive normal-to-normal intervals and mean heart rate) were calculated. During follow-up, an end point committee adjudicated each cause of death. During a mean follow-up time of 2.6±1.0 years, 143 (7.4%) patients died; 92 deaths were attributable to cardiovascular reasons. In a Cox regression model including multiple covariates (age, sex, body mass index, smoking status, history of diabetes mellitus, history of hypertension, history of stroke/transient ischemic attack, history of myocardial infarction, antiarrhythmic drugs including β blockers, oral anticoagulation), a decreased HRV index ≤ median (14.29), but not other HRV parameters, was associated with an increase in the risk of cardiovascular death (hazard ratio, 1.7; 95% CI, 1.1-2.6; P=0.01) and all-cause death (hazard ratio, 1.42; 95% CI, 1.02-1.98; P=0.04). Conclusions The HRV index measured in a single 5-minute ECG recording in a cohort of patients with AF is an independent predictor of cardiovascular mortality. HRV analysis in patients with AF might be a valuable tool for further risk stratification to guide patient management. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT02105844

Association between ventricular repolarization parameters and cardiovascular death in patients of the SWISS-AF cohort.

BACKGROUND The effect of the ventricular repolarization heterogeneity has not been systematically assessed in patients with atrial fibrillation (AF). Aim of this study is to assess ventricular repolarization heterogeneity as predictor of cardiovascular (CV) death and/or other CV events in patients with AF. METHODS From the multicenter prospective Swiss-AF (Swiss Atrial Fibrillation) Cohort Study, we enrolled 1711 patients who were in sinus rhythm (995) or AF (716). Resting ECG recordings of 5-min duration were obtained at baseline. Parameters assessing ventricular repolarization were computed (QTc, Tpeak-Tend, J-Tpeak and V-index). RESULTS During AF, the V-index was found repeatable (no differences when computed over the whole recording, on the first 2.5-min and on the last 2.5-min segments). During a mean follow-up time of 2.6 ± 1.0 years, 90 patients died for CV reasons. In bivariate Cox regression analysis (adjusted for age only), the V-index was associated with an increased risk of CV death, both in the subgroup of patients in sinus rhythm (SR) as well as those in AF. In multivariate analysis adjusted for clinical risk factors and medications, both prolonged QTc and V-index were independently associated with an increased risk of CV death (QTc: hazard ratio [HR] 2.78, 95% CI 1.79-4.32, p < 0.001; V-index: HR 1.73, 95% CI 1.12-2.69, p = 0.014). CONCLUSIONS QTc and V-index, measured in a single 5-min ECG recording, were independent predictors of CV death in a cohort of patients with AF and might be a valuable tool for further risk stratification to guide patient management. Clinical Trial Identifier Swiss-AF study: NCT02105844

Diagnostic and prognostic value of ST-segment deviation scores in suspected acute myocardial infarction

Recent advances in digital electrocardiography technology allow evaluating ST-segment deviations in all 12 leads as quantitative variables and calculating summed ST-segment deviation scores. The diagnostic and prognostic utility of summed ST-segment deviation scores is largely unknown.We aimed to explore the diagnostic and prognostic utility of the conventional and the modified ST-segment deviation score (Better Analysis of ST-segment Elevations and Depressions in a 12- Lead-ECG-Score (BASEL-Score): sum of elevations in the augmented voltage right - lead (aVR) plus absolute, unsigned ST-segment depressions in the remaining leads) in patients presenting with suspected non-ST-segment elevation myocardial infarction. The diagnostic endpoint was non-ST-segment elevation myocardial infarction, adjudicated by two independent cardiologists. Prognostic endpoint was mortality during two-year follow up.Among 1330 patients, non-ST-segment elevation myocardial infarction was present in 200 (15%) patients. Diagnostic accuracy for non-ST-segment elevation myocardial infarction as quantified by the area under the receiver-operating-characteristics curve was significantly higher for the BASEL-Score (0.73; 95% confidence interval 0.69-0.77) as compared to the conventional ST-segment deviation score (0.53; 95% confidence interval 0.49-0.57

Non‐invasive evaluation of new‐onset atrial fibrillation after cardiac surgery: a protocol for the BigMap study

Abstract Aims New‐onset atrial fibrillation (NOAF) is the most common complication after cardiac surgery, occurring in 25–50% of patients. It is associated with post‐operative stroke, increased mortality, prolonged hospital length of stay, and higher treatment costs. Previous small observational studies have identified the left atrium as a source of the electrical rotors and foci maintaining NOAF, but confirmation by a large prospective clinical study is still missing. The aim of the proposed study is to investigate whether the source of NOAF lies in the left atrium. The correct identification of NOAF‐maintaining structures in cardiac surgical patients might offer potential therapeutic targets for prophylactic perioperative ablation strategies. Methods and results This is a prospective single‐centre observational study of patients developing NOAF after cardiac surgery. The primary outcome is the description of NOAF‐maintaining structures within the atria. Key secondary outcomes include overall mortality, intensive care unit length of stay, hospital–ventilator‐free days, and proportion of persistent NOAF. In NOAF patients, the non‐invasive electrophysiological mapping will be conducted using a 252‐electrode electrocardiogram vest. After mapping, a low‐dose computed tomography scan of the chest will be performed to integrate the electrophysiological mapping results into a 3D picture of the heart. The study will include approximately 570 patients, of whom 30% (n = 170) are expected to develop NOAF. Sample size calculation revealed that 157 NOAF patients are necessary to assess the primary outcome. Patients will be tracked for a total of 5 years. Conclusions This is the largest prospective study to date describing the electrophysiological mechanisms of NOAF using non‐invasive mapping