Paced P-wave duration as a significant predictor for atrial high-rate episodes in patients with cardiac implantable electronic devices.

BACKGROUND: Atrial pacing (AP) can unmask or aggravate a preexisting interatrial block (IAB). The aim of our study was to determine whether AP is associated with the development of atrial high-rate episodes (AHRE) during follow-up. METHODS: Patients with dual-chamber cardiac implantable electronic devices (CIEDs), no previous documented atrial fibrillation, and with a 6-month minimum follow-up were included. In all patients, sinus and paced P-wave duration were measured. AHRE was defined as an episode of atrial rate ≥225 bpm with a minimum duration of 5 min, excluding those documented during the first 3 months after implantation. RESULTS: A total of 220 patients were included (75 ± 10 years, 61% male). After a mean follow-up of 59 ± 25 months, 46% of patients presented AHRE. Mean paced P-wave duration was significantly longer than the sinus P-wave duration (154 ± 27 vs. 115 ± 18 ms; p < .001). Sinus and paced P-waves were significantly longer in those who developed AHRE (sinus: 119 ± 20 vs. 112 ± 16; p = .006; paced: 161 ± 29 vs. 148 ± 23; p < .001). A paced P-wave ≥160 ms was the best predictor of AHRE, especially those lasting >24 h (odds ratio [OR] 4.2 [95% confidence interval (CI)] [1.6-11.4]; p = .004). CONCLUSIONS: AP significantly prolongs P-wave duration and is associated with further development of AHRE. A paced P-wave ≥160 ms is a strong predictor of AHRE and should be taken into consideration as a new definition of IAB in the presence of AP.

Atrial fibrillation in elderly patients with implantable loop recorders for unexplained syncope.

BACKGROUND: An implantable loop recorder (ILR) assists in the diagnosis of unexplained syncope and atrial fibrillation (AF). Both become prevalent with age. Limited data exist describing the incidence of AF as the diagnostic rhythm underlying syncope in the elderly. This study aims to report the incidence of AF in older adults with ILRs for unexplained syncope and identify clinical characteristics associated with AF in this population. METHODS: Retrospective observational study on patients with unexplained syncope seen in syncope clinics from two Canadian centers. Participants were ≥65 years old, without a history of AF, and received an ILR for unexplained syncope. Data were collected from patient's clinic charts. Arrhythmia diagnosis was based on ILR electrocardiogram reading during syncope (symptom-rhythm correlation). Fisher's exact test and the Student's t test were used to compare participants with and without AF. RESULTS: In our cohort of 222 patients, 124 were females and 98 were males. Mean age at implant was 80 ± 8 years. Arrhythmia was diagnosed in 98 patients (44.1%). Median time to diagnosis was 18 months. AF was diagnosed in 17 (7.7%) participants. There were fewer males in the AF group than the no AF group (11.8%, 46.8%, p = 0.01). Age, baseline EKG, and prevalence of hypertension, diabetes, stroke, or ischemic heart disease were not statistically different between patients with AF and without AF. CONCLUSIONS: Atrial fibrillation was a common diagnostic rhythm in this cohort of adults, aged 65 and older, with ILRs for unexplained syncope. It was observed more frequently in females.

Novel frequency analysis of signal-averaged electrocardiograms is predictive of adverse outcomes in implantable cardioverter defibrillator patients.

BACKGROUND: Current noninvasive risk stratification methods offer limited prediction of arrhythmic events when selecting patients for ICD implantation. Our laboratory has recently developed a signal processing metric called Layered Symbolic Decomposition frequency (LSDf) that quantifies the percentage of hidden QRS wave frequency components in signal-averaged ECG (SAECG) recordings. The purpose of this pilot study was to determine whether LSDf can be predictive of ventricular arrhythmia or death in an ICD patient cohort. METHODS AND RESULTS: Fifty-two ICD patients were recruited from 2008 to 2009. These were followed for a mean of 8.5 ± 0.4 years for the primary outcome of first appropriately treated ventricular arrhythmia (VT/VF) or death. Thirty-four subjects met the primary outcome. LSDf was significantly lower, and 12-lead QRS duration was significantly greater in patients meeting the primary outcome (12.14 ± 3.97% vs. 16.45 ± 3.73%; p = 0.001) and (111.59 ± 14.96 ms vs. 97.69 ± 13.51 ms; p = 0.012) respectively. A 13.25% LSDf threshold (0.74 sensitivity and 0.85 specificity) was selected based on an ROC curve. Kaplan-Meier survival analysis was conducted; patients above the 13.25% threshold demonstrated significantly better survival outcomes (log-rank p < 0.001). In Cox multivariate regression analysis, the LSDf threshold (13.25%) was compared to LVEF (28.5%), 12-lead QRSd (100 ms), age, % male sex, NYHA classification, and antiarrhythmic usage. LSDf was a predictor of the primary outcome (p = 0.005) and an independent predictor for solely ventricular arrhythmia (p = 0.002). CONCLUSION: Layered Symbolic Decomposition frequency analysis in SAECG recordings may be a viable predictor of negative ICD survival outcomes.

P-wave and interatrial block: New predictor for atrial high rate episodes in patients with cardiac implantable electronic devices.

BACKGROUND: The presence of interatrial block (IAB) is associated with the development of atrial fibrillation (AF). The aim of this study was to determine whether P-wave duration and presence of IAB before the implantation of a cardiac implantable electronic device (CIED) are associated with the presence of atrial high rate episodes (AHRE), during long-term follow-up. METHODS: 380 patients (57% men; 75 ± 10 years) were included. IAB was defined according to the International Consensus Criteria. AHRE was defined as an episode of atrial rate ≥225 beats/min with a minimum duration of 5 minutes. RESULTS: Documented paroxysmal AF before the implantation was present in 24% of the patients; 80% had hypertension and 32% structural heart disease. Mean P-wave duration was 123 ± 23 ms, and 39% of the patients had IAB (32% partial, 7% advanced). After a mean follow-up of 18 ± 12 months, 33% of the patients presented AHRE. Patients with AHRE had a P-wave duration significantly longer (130 ± 24 ms vs 119 ± 21 ms; P < 0.001) and a greater prevalence of IAB (53% vs 32%; P < 0.001). In a multivariate analysis, predictors of AHRE were: IAB (odds ratio [OR] 2.1; 95% confidence interval [CI] [1.3-3.4], P < 0.001) and previous paroxysmal AF (OR 2.6; 95% CI [1.5-4.3], P < 0.001). In patients without previous AF, the presence of IAB was also a significant predictor of AHRE (OR 3.1; 95% CI [1.8-5.5], P < 0.001). CONCLUSIONS: IAB is a strong predictor of AHRE in patients with CIED. This finding is independent of the presence of prior paroxysmal AF.

Use of fragmented QRS in prognosticating clinical deterioration and mortality in pulmonary embolism: A meta-analysis.

BACKGROUND: Fragmented QRS (fQRS) on electrocardiography is potentially valuable in prognosticating acute pulmonary embolism (PE). ECG is one of the first tests performed in the emergency department, quickly interpretable, noninvasive, inexpensive, and available in remote areas. We aimed to review fQRS's role in PE prognostication. METHODS: We searched MEDLINE, EMBASE, Google Scholar, Web of Science, abstracts, conference proceedings, and reference lists until October 2017. Eligible studies used fQRS to prognosticate patients for the main outcomes of death and clinical deterioration or escalation of therapy. Two authors independently selected studies, with disagreement resolved by consensus. Ad hoc piloted forms were used to extract data and assess risk of bias. We used a random-effects model to pool relevant data in meta-analysis with odds ratios (OR) and 95% confidence intervals (CI), while all other data were synthesized qualitatively. Statistical heterogeneity was assessed using the I2 index. RESULTS: We included five studies (1,165 patients). There was complete agreement in study selection. fQRS significantly predicted in-hospital mortality (OR [95% CI], 2.92 [1.73-4.91]; p < .001), cardiogenic shock (OR [95% CI], 4.71 [1.61-13.70]; p = .005), and total mortality at 2-year follow-up (OR [95% CI], 4.42 [2.57-7.60]; p < .001). Adjusted analyses were generally consistent with these results. CONCLUSION: Although few studies have explored the current study's question, they showed that fQRS is potentially valuable in PE prognostication. fQRS should be considered as an entry, along with other clinical and ECG findings, in a PE risk score.

Total cosine R-to-T for predicting ventricular arrhythmic and mortality outcomes: A systematic review and meta-analysis.

BACKGROUND: The total cosine R-to-T (TCRT), a vectorcardiographic marker reflecting the spatial difference between the depolarization and repolarization wavefronts, has been used to predict ventricular tachycardia/fibrillation (VT/VF) and sudden cardiac death (SCD) in different clinical settings. However, its prognostic value has been controversial. OBJECTIVE: This systematic review and meta-analysis evaluated the significance of TRCT in predicting arrhythmic and/or mortality endpoints. METHODS: PubMed and Embase databases were searched through December 31, 2016. RESULTS: Of the 890 studies identified initially, 13 observational studies were included in our meta-analysis. A total of 11,528 patients, mean age 47 years old, 72% male, were followed for 43 ± 6 months. Data from five studies demonstrated lower TCRT values in myocardial infarction patients with adverse events (syncope, ventricular arrhythmias, or sudden cardiac death) compared to those without these events (mean difference = -0.36 ± 0.05, p < .001; I2  = 48%). By contrast, only two studies analyzed outcomes in heart failure, and pooled meta-analysis did not demonstrate significant difference in TCRT between event-positive and event-negative patients (mean difference = -0.01 ± 0.10, p > .05; I2  = 80%). CONCLUSION: TCRT is lower in MI patients at high risk of adverse events when compared to those free from such events. It can provide additional risk stratification beyond the use of clinical parameters and traditional electrocardiogram markers. Its value in other diseases such as heart failure requires further studies.

Meta-analysis of Tpeak-Tend and Tpeak-Tend/QT ratio for risk stratification in congenital long QT syndrome.

BACKGROUND AND OBJECTIVES: Congenital long QT syndrome (LQTS) predisposes affected individuals to ventricular tachycardia/fibrillation (VF/VF), potentially resulting in sudden cardiac death. The Tpeak-Tend interval and the Tpeak-Tend/QT ratio, electrocardiographic markers of dispersion of ventricular repolarization, were proposed for risk stratification but their predictive values in LQTS have been controversial. A systematic review and meta-analysis was conducted to examine the value of Tpeak-Tend intervals and Tpeak-Tend/QT ratios in predicting arrhythmic and mortality outcomes in congenital LQTS. METHOD: PubMed and Embase databases were searched until 9th May 2017, identifying 199 studies. RESULTS: Five studies on long QT syndrome were included in the final meta-analysis. Tpeak-Tend intervals were longer (mean difference [MD]: 13ms, standard error [SE]: 4ms, P=0.002; I2=34%) in congenital LQTS patients with adverse events [syncope, ventricular arrhythmias or sudden cardiac death] compared to LQTS patients without such events. By contrast, Tpeak-Tend/QT ratios were not significantly different between the two groups (MD: 0.02, SE: 0.02, P=0.26; I2=0%). CONCLUSION: This meta-analysis showed that Tpeak-Tend interval is significant higher in individuals who are at elevated risk of adverse events in congenital LQTS, offering incremental value for risk stratification.

The value of electrocardiographic abnormalities in the prognosis of pulmonary embolism: a consensus paper.

Electrocardiographic (ECG) abnormalities in the setting of acute pulmonary embolism (PE) are being increasingly characterized and mounting evidence suggests that ECG plays a valuable role in prognostication for PE. We review the historical 21-point ECG prognostic score for the severity of PE and examine the updated evidence surrounding the utility of ECG abnormalities in prognostication for severity of acute PE. We performed a literature search of MEDLINE, EMBASE, and PubMed up to February 2015. Article titles and abstracts were screened, and articles were included if they were observational studies that used a surface 12-lead ECG as the instrument for measurement, a diagnosis of PE was confirmed by imaging, arteriography or autopsy, and analysis of prognostic outcomes was performed. Thirty-six articles met our inclusion criteria. We review the prognostic value of ECG abnormalities included in the 21-point ECG score, including new evidence that has arisen since the time of its publication. We also discuss the potential prognostic value of several ECG abnormalities with newly identified prognostic value in the setting of acute PE.

Validation of a novel algorithm for quantification of the percentage of signal fractionation in atrial fibrillation.

AIMS: Catheter ablation for paroxysmal atrial fibrillation (AF) is rapidly becoming a standard practice. There is literature to support that catheter ablation of persistent AF requires additional 'substrate modification'. In clinical practice, operators rely on automated fractionation maps created by three-dimensional anatomic mapping systems to rapidly assess complex 'fractionated' signals (CFAE). These systems use differing algorithms to automate the process. The agreement between operators and contemporary algorithms has not been examined. We sought to assess the agreement between operators and a novel method of quantification calculating percentage fractionation (PF). METHODS AND RESULTS: Expert opinion on 80 atrial electrogram 4 s signals of varying levels of activity were gathered and pooled for comparison. Twelve independent experts visually quantified the signal fractionation and offered a threshold level for ablation. We developed an algorithm to find sites with high continuous electrical activity, or high PF. Correlation between experts and PF was 0.78 [P < 0.01, 95% confidence interval (CI) (0.68-0.86)]. Receiver operating characteristics curve sensitivity and specificity for PF were 0.7727 and 0.8103 at the optimal cut-off point of 58.45 PF with area under curve 0.89 CI (0.80-0.99). CONCLUSION: The PF statistic represents a more robust and intuitive measure to represent fractionated atrial activity; importantly it demonstrates excellent agreement with expert users and presents a new standard for algorithm assessment. Use of a PF statistic should be considered in automated mapping systems.

Temporo-spatial stability of complex fractionated atrial electrograms in two distinct and separate episodes of paroxysmal atrial fibrillation.

AIMS: Ablation of complex fractionated atrial electrograms (CFAEs) during atrial fibrillation (AF) has been used as adjunct to contemporary techniques or as an alternative. Temporo-spatial stability of CFAE has been demonstrated in single episodes of AF. We examined temporo-spatial reproducibility of CFAE in two distinct episodes of AF. METHODS AND RESULTS: The left atrium (LA) was mapped using the EnSite system during an episode of induced or spontaneous AF in patients with paroxysmal AF. Sinus rhythm was restored with electrical cardioversion and maintained for 10 min before re-induction of AF and repeat mapping. Maps were compared examining the mean cycle length at identical vertices, provided the anatomical point had data on both maps. Complex fractionated atrial electrograms were considered stable if the compared electrogram was within 50 ms--delta to 120 ms + delta. Eleven patients were studied; 10 were included [3 female, mean age 59.5 years (32-76)]. Complex fractionated atrial electrograms were observed in all regions of the LA. Complex fractionated atrial electrograms were evenly distributed throughout the LA but most reproducible at the roof and antero-lateral wall. Complex fractionated atrial electrograms were highly conserved between two episodes of AF with 76.1 +/- 11.8% of CFAE reproducible at delta of 20 ms. CONCLUSION: Complex fractionated atrial electrograms are reproducible at the same anatomic site in a separate episode of AF.

Right ventricular apical lead position is associated with prolonged signal-averaged P-wave duration.

AIM: The study aimed to determine if right ventricular apical pacing is associated with adverse change in atrial substrate compared with right ventricular septal pacing. METHODS: Patients with septal leads and dual-chamber devices with more than 3 months of follow-up and 70% or higher cumulative percentage of ventricular pacing were compared with a matched group of apically implanted leads with a cumulative percentage ventricular pacing of 70% or higher. Device parameters were recorded, and high-resolution recordings were obtained for signal-averaged P-wave (SAPW) analysis. Previously obtained SAPW recordings taken from 49 healthy patients and 73 patients with paroxysmal atrial fibrillation were used as negative and positive controls, respectively. RESULTS: Ten patients with septal leads (mean age, 71.9 +/- 12.1 years; mean months implanted, 10.5 +/- 3.2 months) and 9 patients with apical leads (mean age, 71.9 +/- 5.7 years; mean months implanted, 11.4 +/- 6.4 months) were enrolled. The SAPW duration was longer in the apical cohort compared with the septal cohort (144.8 +/- 6.9 and 133.0 +/- 5.5 milliseconds, respectively; P = .001), whereas there was no significant difference between septal and normal cohorts (133.0 +/- 5.5 and 129.3 +/- 7.1 milliseconds, respectively; P = .08). CONCLUSIONS: Apical pacing is associated with prolonged P-wave duration relative to septal pacing and controls: this may manifest as increased risk of atrial tachycardias and presents a potentially novel benefit of septal pacing.

The value of electrocardiography in prognosticating clinical deterioration and mortality in acute pulmonary embolism: A systematic review and meta-analysis.

The role of electrocardiography (ECG) in prognosticating pulmonary embolism (PE) is increasingly recognized. ECG is quickly interpretable, noninvasive, inexpensive, and available in remote areas. We hypothesized that ECG can provide useful information about PE prognostication. We searched MEDLINE, EMBASE, Google Scholar, Web of Science, abstracts, conference proceedings, and reference lists through February 2017. Eligible studies used ECG to prognosticate for the main outcomes of death and clinical deterioration or escalation of therapy. Two authors independently selected studies; disagreement was resolved by consensus. Ad hoc piloted forms were used to extract data and assess risk of bias. We used a random-effects model to pool relevant data in meta-analysis with odds ratios (ORs) and 95% confidence intervals (CIs); all other data were synthesized qualitatively. Statistical heterogeneity was assessed using the I 2 value. We included 39 studies (9198 patients) in the systematic review. There was agreement in study selection (κ: 0.91, 95% CI: 0.86-0.96). Most studies were retrospective; some did not appropriately control for confounders. ECG signs that were good predictors of a negative outcome included S1Q3T3 (OR: 3.38, 95% CI: 2.46-4.66, P < 0.001), complete right bundle branch block (OR: 3.90, 95% CI: 2.46-6.20, P < 0.001), T-wave inversion (OR: 1.62, 95% CI: 1.19-2.21, P = 0.002), right axis deviation (OR: 3.24, 95% CI: 1.86-5.64, P < 0.001), and atrial fibrillation (OR: 1.96, 95% CI: 1.45-2.67, P < 0.001) for in-hospital mortality. Several ischemic patterns also were significantly predictive. Our conclusion is that ECG is potentially valuable in prognostication of acute PE.

Implantable loop recorders in the real world: a study of two Canadian centers.

PURPOSE: Implantable loop recorders (ILRs) are increasingly being used for ambulatory electrocardiography. We sought to evaluate ILR indications, diagnostic yield, ILR-guided interventions, and complications in two Canadian centers. METHODS: This was a retrospective study using electronic medical records to identify ILR implants at Queen's University and the University of Manitoba. Information was collected on patient characteristics, medications, indication for implant, results of prior investigations, diagnostic outcome, and subsequent management. RESULTS: A total of 540 patients were identified; 386 had completed monitoring at time of analysis. Forty patients were lost to follow-up. Indications were unexplained syncope 84.8%, palpitations 12.8%, and suspected atrial fibrillation 11.7%. For syncope, ILRs documented arrhythmia or conduction disorder in 46%. Most common conditions were asystole/sinus pause (22%), complete heart block (10.4%), and atrial fibrillation (AF) (6.9%). After ILR diagnosis, 39.9% of implanted patients received pacemaker/ICD and 2.7% underwent catheter ablation. For palpitations, ILRs documented arrhythmia or conduction disorder in 60.4%. Most common conditions were AVNRT, AF, complete heart block, and ventricular tachycardia. After diagnosis, 25% underwent catheter ablation and 22.9% received pacemaker/ICD. For suspected AF, AF was diagnosed in 40%. Complications were observed in 3.3% of implanted patients: implant site infection 1.5%, non-infectious implant site pain requiring device removal or pocket revision 1.5%, 0.2% hypertrophic scar, and 0.2% device malfunction. CONCLUSIONS: An ILR has excellent diagnostic yield for syncope, palpitations, and suspected AF, and a considerable proportion of patients undergo ILR-directed interventions following monitoring. ILR implantation is a low-risk procedure.

Frailty and Mortality Outcomes After Percutaneous Coronary Intervention: A Systematic Review and Meta-Analysis.

BACKGROUND: Frailty has been identified as a risk factor for mortality. However, whether frailty increases mortality risk in patients undergoing percutaneous coronary intervention (PCI) has been controversial. Therefore, we conducted a systematic review and meta-analysis of the frailty measures and mortality outcomes in this setting. METHODS: PubMed and EMBASE were searched until July 23, 2017 for studies evaluating the association between frailty measures and mortality in individuals who have undergone PCI. RESULTS: A total of 141 entries were retrieved from our search strategy. A total of 8 studies involving 2332 patients were included in the final meta-analysis (mean age: 69 years; 68% male, follow-up duration was 30 ± 28 months). Frailty was a significant predictor of all-cause mortality after PCI, with a hazard ratio (HR) of 2.97 [95% confidence interval (CI) 1.56-5.66, P = .001]. This was substantial heterogeneity present (I2: 79%). Subgroup analysis using the Fried score reduced I2 to 68% without altering the pooled HR (2.78, 95% CI 1.02-7.76; P < .05). Using the Canadian Study of Health and Aging Clinical Frailty Scale reduced I2 to 0% while preserving the pooled HR (5.99, 95% CI 2.77-12.95, P < .001). CONCLUSIONS: Frailty leads to significantly higher mortality rates in patients who have undergone PCI. Both the Fried score and Canadian Study of Health and Aging Clinical Frailty Scale are powerful predictors of mortality. These findings may support the notion that an alternative to invasive strategy should be considered in frail patients who are indicated for revascularization.

Arritmia ventricular en el postoperatorio inmediato de cirugía cardiovascular / Postoperating ventricular arrhythmia in the immediate one of cardiovascular surgery

Objetivos: Determinar la incidencia, factores predisponentes y la evolución hospitalaria de la arritmia ventricular compleja en el postoperatorio inmediato de cirugía cardíaca. Material y métodos: Se analizó las primeras 96 hs. del postoperatorio de cirugía cardíaca en 35 pacientes (pts) consecutivos, considerando como arritmia ventricular compleja (AC) a la taquicardia ventricular autolimitada, sostenida y fibrilación ventricular. Se registraron factores predisponentes pre, intra y postoperatorios y la evolución hospitalaria. Resultados: Se efectuo revascularización miocárdica en 273 pts (77 por ciento), cirugía valvular en 74 pts (21 por ciento) y procedimientos combinados en 8 pts (2 por ciento). Presentaron AC 25 pts (7 por ciento), detectando Taquicardia Ventricular Sostenida en 11 pts (44 por ciento) y Fibrilación Ventricular en 7 pts (28 por ciento). La Arritmia ventricular compleja resultó más frecuente en pts sometidos a revascularización miocárdica (9,1 por ciento vs 0 por ciento; p<0,005), asociada al uso de intrópicos (64 por ciento vs 34 por ciento, p<0, 005) o por isquemia o infarto perioperatorio (48 por ciento vs 16 por ciento, p<0,0001). El tiempo de bomba fue mayor en pacientes con Arritmia ventricular compleja (142,4 ± 45,1 vs 106,3 ± 30,1 min.; p<0,0005). Las variables independientes de riesgo fueron: Revascularización miocárdiaca (OR 7,52), uso de inotrópicos (OR 2,63) e incrento del tiempo de bomba (OR 1,02). Sólo el 0.5 por ciento de las Arritmias ventriculares complejas no presentaron factores desencadenantes. La mortalidad del grupo con arritmias fue 52 por ciento, y sin ellas 5 por ciento (p<0,001). La mortalidad por toda causa en Taquicardia Ventricular Autolimitada fue 14 por ciento, 45 por ciento en Taquicardia ventricular sostenida y 100 por ciento en Fibrilación ventricular. Conclusiones: La Arritmia ventricular compleja es una complicación de alta mortalidad, relacionada a factores inherentes al procedimiento de revascularización miocárdiaca.