This novel cumulative ECG risk score was independently associated with SCD and was particularly effective for LVEF >35% where risk stratification is currently unavailable. These findings warrant further evaluation in prospective clinical investigations.

Background Prolongation of initial ventricular depolarization on the 12-lead ECG, or delayed intrinsicoid deflection (DID), can indicate left ventricular hypertrophy (LVH). The possibility that this marker could convey distinct risk of sudden cardiac arrest (SCA) has not been evaluated. Objective To evaluate the association of DID and SCA in the community. Methods In the ongoing prospective, population-based Oregon Sudden Unexpected Death Study (Oregon SUDS, catchment area approx. 1 million), SCA cases were compared to geographic controls with no SCA. Archived ECGs (closest and unrelated to SCA event for cases) were evaluated for the presence of DID defined as ≥0.05 seconds in leads V5 or V6. LV mass and function were evaluated from archived echocardiograms. Results SCA cases (n=272, 68.7±14.6 years, 63.6% male) as compared to controls (n=351, 67.6±11.4 years, 63.3% male) were more likely to have DID on ECG (28.3% vs 17.1%, p=0.001). DID was associated with increased SCA odds (OR 1.92; 95% CI 1.31-2.81; p=0.001), but showed poor correlation with LV mass and echocardiographic LVH (kappa 0.13). In multivariate analysis adjusted for clinical and ECG markers, reduced LV ejection fraction and echocardiographic LVH, DID remained an independent predictor of SCA (OR 1.82; 95% CI 1.12-2.97; p=0.016). Additionally, in a sensitivity analysis restricted to narrow QRS, DID and ECG LVH by voltage were each independently associated with SCA risk. Conclusion DID was associated with increased SCA risk independent of echocardiographic LVH, ECG LVH and reduced LV ejection fraction, potentially reflecting unique electrical remodeling that warrants further investigation.

Background: Up to two-thirds of patients with obstructive coronary artery disease (CAD) have silent ischemia (SI), which predicts an adverse prognosis and can be a treatment target in obstructive CAD. Over 50% of women with ischemia and no obstructive CAD have coronary microvascular dysfunction (CMD), which is associated with adverse cardiovascular outcomes. We aimed to investigate the prevalence of SI in CMD in order to consider it as a potential treatment target.Methods: 36 women with CMD by coronary reactivity testing and 16 age matched reference subjects underwent 24-hr 12-lead ambulatory ECG monitoring (Mortara Instruments) after antiischemia medication withdrawal. Ambulatory ECG recordings were reviewed by two-physician consensus masked to subject status for SI measured by evidence of ≥ 1 minute horizontal or downsloping ST segment depression ≥ 1.0 mm, measured 80 ms from the J point.Results: Demographics, resting heart rate, and systolic blood pressure were similar between CMD and reference subjects. Thirty-nine percent of CMD women had a total of 26 SI episodes vs. 0 episodes in the reference group (p=0.002). Among these women 13/14 (93%) had SI, and few episodes (3/26, 12%) were symptomatic. Mean HR at the onset of SI was 96±13 bpm and increased to 117±16 bpm during the ischemic episodes. 87% reported symptoms that were not associated with ST depressions.

Introduction The Romhilt-Estes point score system (RE) is an established ECG criterion for diagnosing left ventricular hypertrophy (LVH). In this study, we assessed for the first time, whether RE and its components are predictive of sudden cardiac arrest (SCA) independent of left ventricular (LV) mass. Methods SCA cases occurring between 2002 and 2014 in a Northwestern US metro region (catchment area approx. 1 million) were compared to geographic controls. ECGs and echocardiograms prior to the SCA and those of controls were acquired from the medical records and evaluated for the ECG criteria established in the RE score and for LV mass. Results 247 SCA cases (age 68.3±14.6, male 64.4%) and 330 controls (age 67.4±11.5, male 63.6) were included in the analysis. RE scores were greater in cases than controls (2.5±2.1 vs. 1.9±1.7, p <0.001), and SCA cases were more likely to meet definite LVH criteria (18.6% vs. 7.9%, p <0.001). In a multivariable model including echocardiographic LVH and LV function, definite LVH remained independently predictive of SCA (OR 2.04 95% CI 1.16–3.59, p=0.013). The model was replicated with the individual ECG criteria, and only SV1.2 ≥30 mm and delayed intrinsicoid deflection remained significant predictors of SCA. Conclusion LVH as defined by the RE point score system is associated with SCA independent of echocardiographic LVH and reduced LV ejection fraction. These findings support an independent role for purely electrical LVH, in the genesis of lethal ventricular arrhythmias.