Ankit Maheshwari

Low Heart Rate Variability in a 2-Minute Electrocardiogram Recording Is Associated with an Increased Risk of Sudden Cardiac Death in the General Population: The Atherosclerosis Risk in Communities Study.

Low heart rate variability (HRV) has been linked to increased total mortality in the general population; however, the relationship between low HRV and sudden cardiac death (SCD) is less well-characterized. The goal of this study was to evaluate the relationship between low HRV and SCD in a community-based cohort. Our cohort consisted of 12,543 participants from the Atherosclerosis Risk in Communities (ARIC) study. HRV measures were derived from 2-minute electrocardiogram recordings obtained during the baseline exam (1987–89). Time domain measurements included the standard deviation of all normal RR intervals (SDNN) and the root mean squared successive difference (r-MSSD). Frequency domain measurements included low frequency power (LF) and high frequency (HF) power. During a median follow-up of 13 years, 215 SCDs were identified from physician adjudication of all coronary heart disease deaths through 2001. In multivariable adjusted Cox proportional hazards models, each standard deviation decrement in SDNN, LF, and HF were associated with 24%, 27% and 16% increase in SCD risk, respectively. Low HRV is independently associated with increased risk of SCD in the general population.

Relation of the Brugada Phenocopy to Hyperkalemia (from the International Registry on Brugada Phenocopy)

Brugada phenocopies (BrPs) are clinical entities that differ in etiology from true congenital Brugada syndrome but have identical electrocardiographic (ECG) patterns. Hyperkalemia is known to be one of the causes of BrP. The aim of this study was to determine the clinical characteristics and evolution of hyperkalemia-induced BrP. Data from 27 cases of hyperkalemia-induced BrP were collected from the International Registry at www.brugadaphenocopy.com. Data were extracted from publications. Of the 27 patients included in the analysis, 18 (67%) were male; mean age was 53 ± 15 years (range 31 to 89). Mean serum potassium concentration was 7.45 ± 0.89 mmol/L. Type-1 Brugada ECG pattern was observed in 21 cases (78%), whereas 6 cases (22%) showed a type-2 Brugada ECG pattern. The Brugada ECG pattern resolved once the hyperkalemia was corrected, with no arrhythmic events. Estimated time to resolution was 7 ± 3 hours. In 4 cases (16%), a concurrent metabolic abnormality was detected: 3 (11%) presented with acidosis, 2 (7%) with hyponatremia, 1 (4%) with hypocalcaemia, 1 (4%) with hyperphosphatemia, and 1 (4%) with hyperglycemia. In 7 cases (26%), provocative testing using sodium channel blockers was performed, and all failed to reproduce a BrS ECG pattern (BrP class A). Additionally, no sudden cardiac death or malignant ventricular arrhythmias were detected. Hyperkalemia was found a common cause of BrP in our International Registry. The Brugada ECG pattern appears to occur at high serum potassium concentrations (>6.5 mmol/L). The ECG normalizes within hours of correcting the electrolyte imbalance. Importantly, hyperkalemia-induced BrP has not been associated with sudden cardiac death or ventricular arrhythmia.

Abnormal P-Wave Axis and Ischemic Stroke: The ARIC Study (Atherosclerosis Risk In Communities)

Background and Purpose— Abnormal P-wave axis (aPWA) has been linked to incident atrial fibrillation and mortality; however, the relationship between aPWA and stroke has not been reported. We hypothesized that aPWA is associated with ischemic stroke independent of atrial fibrillation and other stroke risk factors and tested our hypothesis in the ARIC study (Atherosclerosis Risk In Communities), a community-based prospective cohort study. Methods— We included 15 102 participants (aged 54.2±5.7 years; 55.2% women; 26.5% blacks) who attended the baseline examination (1987–1989) and without prevalent stroke. We defined aPWA as any value outside 0 to 75° using 12-lead ECGs obtained during study visits. Each case of incident ischemic stroke was classified in accordance with criteria from the National Survey of Stroke by a computer algorithm and adjudicated by physician review. Multivariable Cox regression was used to estimate hazard ratios and 95% confidence intervals for the association of aPWA with stroke. Results— During a mean follow-up of 20.2 years, there were 657 incident ischemic stroke cases. aPWA was independently associated with a 1.50-fold (95% confidence interval, 1.22–1.85) increased risk of ischemic stroke in the multivariable model that included atrial fibrillation. When subtyped, aPWA was associated with a 2.04-fold (95% confidence interval, 1.42–2.95) increased risk of cardioembolic stroke and a 1.32-fold (95% confidence interval, 1.03–1.71) increased risk of thrombotic stroke. Conclusions— aPWA is independently associated with ischemic stroke. This association seems to be stronger for cardioembolic strokes. Collectively, our findings suggest that alterations in atrial electric activation may predispose to cardiac thromboembolism independent of atrial fibrillation.

Abnormal P-Wave Axis and Ischemic Stroke

Background and Purpose— Abnormal P-wave axis (aPWA) has been linked to incident atrial fibrillation and mortality; however, the relationship between aPWA and stroke has not been reported. We hypothesized that aPWA is associated with ischemic stroke independent of atrial fibrillation and other stroke risk factors and tested our hypothesis in the ARIC study (Atherosclerosis Risk In Communities), a community-based prospective cohort study. Methods— We included 15 102 participants (aged 54.2±5.7 years; 55.2% women; 26.5% blacks) who attended the baseline examination (1987–1989) and without prevalent stroke. We defined aPWA as any value outside 0 to 75° using 12-lead ECGs obtained during study visits. Each case of incident ischemic stroke was classified in accordance with criteria from the National Survey of Stroke by a computer algorithm and adjudicated by physician review. Multivariable Cox regression was used to estimate hazard ratios and 95% confidence intervals for the association of aPWA with stroke. Results— During a mean follow-up of 20.2 years, there were 657 incident ischemic stroke cases. aPWA was independently associated with a 1.50-fold (95% confidence interval, 1.22–1.85) increased risk of ischemic stroke in the multivariable model that included atrial fibrillation. When subtyped, aPWA was associated with a 2.04-fold (95% confidence interval, 1.42–2.95) increased risk of cardioembolic stroke and a 1.32-fold (95% confidence interval, 1.03–1.71) increased risk of thrombotic stroke. Conclusions— aPWA is independently associated with ischemic stroke. This association seems to be stronger for cardioembolic strokes. Collectively, our findings suggest that alterations in atrial electric activation may predispose to cardiac thromboembolism independent of atrial fibrillation.

Hyperkalemia-Induced Brugada Phenocopy

A 65 year-old man with a history of type 1 diabetes previously treated with an auto islet cell transplant presented with acute kidney injury (creatinine 1.5 mg/dl) and asymptomatic hyperkalemia (K+, 6.8 mEq/l). The electrocardiogram revealed >2 mm coved ST-segment elevation with T-wave inversion in

Adding fuel to the fire: Coronary artery dissection complicating blunt chest trauma

A 21year-old male presented to the emergency department with 6 h of atypical chest pain after suffering blunt chest trauma. His electrocardiogram revealed 1-1.5mm ST segment elevation in leads V1-V3 with reciprocal depressions in II, III, and aVF. Mid-anterior wall akinesis was observed on echocardiography associated with an estimated left ventricular ejection fraction of 40%. A left main coronary artery dissection was diagnosed and treated surgically with a bypass graft. Although rare, coronary dissections can be a catastrophic complication of chest trauma.

Refining Prediction of Atrial Fibrillation Risk in the General Population With Analysis of P-Wave Axis (from the Atherosclerosis Risk in Communities Study)

Adverse atrial remodeling is associated with increased risk of atrial fibrillation (AF) and can be detected by a shift in P-wave axis. We aimed to determine whether an analysis of P-wave axis can be used to improve risk prediction of AF. We included 15,102 Atherosclerosis Risk in Communities Study participants who were free of AF at baseline. Abnormal P-wave axis (aPWA) was defined as any value outside 0 to 75 degrees on study visit 12-lead electrocardiograms. AF was determined using study visit electrocardiograms, death certificates, and hospital discharge records. Multivariable Cox regression was used to estimate hazard ratios and 95% confidence intervals (CIs) for the association of aPWA with AF. The Cohorts for Heart and Aging Research in Genomic Epidemiology-AF (CHARGE-AF) risk prediction model variables served as our benchmark. Improvement in 10-year AF prediction was assessed by C-statistic, category-based net reclassification improvement, and relative integrated discrimination improvement. During a mean follow-up of 20.2 years, there were 2,618 incident AF cases. aPWA was independently associated with a 2.34-fold (95% CI 2.12 to 2.58) increased risk of AF after adjusting for CHARGE-AF risk score variables. The use of aPWA improved the C-statistic from 0.719 (95% CI 0.702 to 0.736) to 0.722 (95% CI 0.705 to 0.739), which corresponded with a net reclassification improvement of 0.021 (95% CI 0.001, 0.040) and relative integrated discrimination improvement of 0.043 (95% CI 0.018, 0.069). In conclusion, aPWA is independently associated with AF in the general population. The use of this maker modestly improves AF prediction.

Specific Brugada Phenocopies: Electrolyte and Metabolic Disorders

Abstract Brugada Phenocopies (BrP) are clinical entities characterized by electrocardiographic (ECG) patterns identical to those seen in congenital Brugada Syndrome (BrS), but which are induced by various clinical circumstances. Electrolyte imbalance and metabolic disorders can cause electrical alterations identical to those produced by congenital BrS ionic channel dysfunction. In this chapter, we review the most common electrolyte and metabolic abnormalities presenting as BrP.

Predictors of sudden cardiac death in atrial fibrillation: The Atherosclerosis Risk in Communities (ARIC) study

We previously reported that incident atrial fibrillation (AF) is associated with an increased risk of sudden cardiac death (SCD) in the general population. We now aimed to identify predictors of SCD in persons with AF from the Atherosclerosis Risk in Communities (ARIC) study, a community-based cohort study. We included all participants who attended visit 1 (1987–89) and had no prior AF (n = 14,836). Incident AF was identified from study electrocardiograms and hospitalization discharge codes through 2012. SCD was physician-adjudicated. We used cause-specific Cox proportional hazards models, followed by stepwise selection (backwards elimination, removing all variables with p>0.10) to identify predictors of SCD in participants with AF. AF occurred in 2321 (15.6%) participants (age 45–64 years, 58% male, 18% black). Over a median of 3.3 years, SCD occurred in 110 of those with AF (4.7%). Predictors of SCD in AF included higher age, body mass index (BMI), coronary heart disease, hypertension, diabetes, current smoker, left ventricular hypertrophy, increased heart rate, and decreased albumin. Predictors associated only with SCD and not other cardiovascular (CV) death included increased BMI (HR per 5-unit increase, 1.15, 95% CI, 0.97–1.36, p = 0.10), increased heart rate (HR per SD increase, 1.18, 95% CI 0.99–1.41, p = 0.07), and low albumin (HR per SD decrease 1.23, 95% CI 1.02–1.48, p = 0.03). In the ARIC study, predictors of SCD in AF that are not associated with non-sudden CV death included increased BMI, increased heart rate, and low albumin. Further research to confirm these findings in larger community-based cohorts and to elucidate the underlying mechanisms to facilitate prevention is warranted.