Anticoagulants for atrial fibrillation: from warfarin and DOACs to the promise of factor XI inhibitors.

Anticoagulation is the mainstay of stroke prevention in appropriate patients with atrial fibrillation. Due to advances in pharmacotherapy the anticoagulants used for this purpose have evolved significantly over the past decades with the aim of optimizing effectiveness while minimizing bleeding risks. Though significant improvements have been made toward this goal, bleeding risk remains the major concern with these therapies. An investigational class of agents which inhibit Factor XI have shown promise in pre-clinical and early clinical trials to significantly minimize bleeding while maintaining efficacy against stroke and systemic embolism. This mini-review will discuss anticoagulants currently used for stroke prevention in patients with atrial fibrillation including warfarin and direct oral anticoagulants. We will also review the mechanism of action and data from early clinical trials for Factor XI inhibitors and discuss their potential advantages and shortcomings.

Electrocardiographic Associations of Cardiac Biomarkers and Cardiac Magnetic Resonance Measures of Fibrosis in the Multiethnic Study of Atherosclerosis (MESA).

Abnormalities in myocardial substrate, including diffuse and replacement fibrosis, increase the risk of cardiovascular disease (CVD). Data are sparse on whether electrocardiogram (ECG) measures, coupled with circulating biomarkers, may aid in identifying cardiac fibrosis. This study aimed to determine whether 12-lead ECG and biomarkers together augment the prediction of cardiac fibrosis in participants who are free of known CVD. This is a cross-sectional analysis in the MESA (Multiethnic Study of Atherosclerosis) study at visit 5 (2010 to 2012), with measurements of biomarkers (cardiac troponin T and growth differentiation factor-15), gadolinium-enhanced cardiac magnetic resonance imaging, and ECG. Logistic regression associations of ECG measures with cardiac magnetic resonance surrogates of fibrosis (highest quartile extracellular volume [interstitial fibrosis] and late gadolinium enhancement [replacement fibrosis]) were adjusted for demographics and risk factors. Using the C-statistic, we evaluated whether adding ECG measures and biomarkers to clinical characteristics improved the prediction of either type of fibrosis. There were 1,170 eligible participants (aged 67.1 ± 8.6 years). Among the ECG measures, QRS duration (odds ratio [OR] 1.41 per 10 ms, 95% confidence interval [CI] 1.10 to 1.81), major ST-T abnormalities (OR 3.03, 95%CI 1.20, 7.65), and abnormal QRS-T angle (OR 6.32, 95%CI 3.00, 13.33) were associated with replacement fibrosis, whereas only abnormal QRS-T angle (OR 3.05, 95%CI,1.69, 5.48) was associated with interstitial fibrosis. ECG markers, in addition to clinical characteristics, improved the prediction of replacement fibrosis (p = 0.002) but not interstitial fibrosis. The addition of cardiac troponin T and growth differentiation factor-15 to the ECG findings did not significantly improve the model discrimination for either type of cardiac fibrosis. In CVD free participants, simple ECG measures are associated with replacement fibrosis and interstitial fibrosis. The addition of these measures improves identification of replacement but not interstitial fibrosis. These findings may help refine the identification of myocardial scar in the general population.

Association of cardiac troponin T and growth differentiation factor 15 with replacement and interstitial cardiac fibrosis in community dwelling adults: The multi-ethnic study of atherosclerosis.

Background: Subclinical abnormalities in myocardial structure (stage B heart failure) may be identified by cardiac and non-organ specific biomarkers. The associations of high-sensitivity cardiac troponin T (hs-cTnT) and growth differentiation factor-15 (GDF-15) with cardiac magnetic resonance imaging (CMR) interstitial fibrosis (extracellular volume [ECV]) is unknown and for GDF-15 the association with replacement (late gadolinium enhancement [LGE]) is also unknown. GDF-15 is a systemic biomarker also released by myocytes associated with fibrosis and inflammation. We sought to define the associations of hs-cTnT and GDF-15 with these CMR fibrosis measures in the MESA cohort. Methods: We measured hs-cTnT and GDF-15 in MESA participants free of cardiovascular disease at exam 5. CMR measurements were complete in 1737 for LGE and 1258 for ECV assessment. We estimated the association of each biomarker with LGE and increased ECV (4th quartile) using logistic regression, adjusted for demographics and risk factors. Results: Mean age of the participants was 68 ± 9 years. Unadjusted, both biomarkers were associated with LGE, but after adjustment only hs-cTnT concentrations remained significant (4th vs. 1st quartile OR] 7.5, 95% CI: 2.1, 26.6). For interstitial fibrosis both biomarkers were associated with 4th quartile ECV, but the association was attenuated compared to replacement fibrosis. After adjustment, only hs-cTnT concentrations remained significant (1st to 4th quartile OR 1.7, 95%CI: 1.1, 2.8). Conclusion: Our findings identify that both interstitial and replacement fibrosis are associated with myocyte cell death/injury, but GDF-15 a non-organ specific biomarker prognostic for incident cardiovascular disease is not associated with preclinical evidence of cardiac fibrosis.

Detailed thrombogenicity phenotyping and 1 year outcomes in patients undergoing WATCHMAN implantation: (TARGET-WATCHMAN) a case-control study.

The relation of device related thrombosis (DRT) and major bleeding after left atrial appendage closure (LAAC) to laboratory thrombosis and hemostasis markers has not been studied. We performed a prospective case control study to identify clinical characteristics and laboratory markers in patients who developed DRT and major bleeding following WATCHMAN LAAC. Thromboelastography, platelet aggregation (PA), urinary 11-dehydrothromboxane B2 (UTX), fibrinogen, D-dimer, thrombin time and von Willebrand factor activity were determined at baseline, immediately following, and at 45 and 180 days post-LAAC (n = 32) and outcomes were followed for 1 year. Baseline characteristics and thrombogenic profiles of patients with and without DRT and/or BARC bleeding were compared. Mean age was 76 ± 8 years and CHADS2 VASc score was 4.4 ± 1.4. There were 3 DRTs (2 within 6 months, and 1 at 12 months), 4 Type 3A BARC bleeds, and 2 non-cardiac deaths. Patients with DRT had higher baseline thrombin-induced platelet-fibrin clot strength (68.0 ± 1.8 vs. 62.7 ± 4.7 mm, p = 0.06); FCS (35.6 ± 6.0 vs. 24.4 ± 6.6 mm, p = 0.009); and D-dimer (1712 ± 2330 vs. 283 ± 213 ng/mL, p = 0.001). At baseline, 5 patients had all 3 factors associated with high thrombotic risk and 2 experienced a DRT within 6 months. Patients with Type 3A BARC bleeding had lower baseline collagen-induced and 45-day ADP-induced PA (p < 0.01 for both). DRT following LAAC was associated with a baseline prothrombogenic profile whereas bleeding was associated with low platelet reactivity. These preliminary findings warrant further validation and have future implications on patient selection and adjunctive antithrombotic therapy following LAAC.Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT03040622 .

Bucindolol for the Maintenance of Sinus Rhythm in a Genotype-Defined HF Population: The GENETIC-AF Trial.

OBJECTIVES: The purpose of this study was to compare the effectiveness of bucindolol with that of metoprolol succinate for the maintenance of sinus rhythm in a genetically defined heart failure (HF) population with atrial fibrillation (AF). BACKGROUND: Bucindolol is a beta-blocker whose unique pharmacologic properties provide greater benefit in HF patients with reduced ejection fraction (HFrEF) who have the beta1-adrenergic receptor (ADRB1) Arg389Arg genotype. METHODS: A total of 267 HFrEF patients with a left ventricular ejection fraction (LVEF) <0.50, symptomatic AF, and the ADRB1 Arg389Arg genotype were randomized 1:1 to receive bucindolol or metoprolol therapy and were up-titrated to target doses. The primary endpoint of AF or atrial flutter (AFL) or all-cause mortality (ACM) was evaluated by electrocardiogram (ECG) during a 24-week period. RESULTS: The hazard ratio (HR) for the primary endpoint was 1.01 (95% confidence interval [CI]: 0.71 to 1.42), but trends for bucindolol benefit were observed in several subgroups. Precision therapeutic phenotyping revealed that a differential response to bucindolol was associated with the interval of time from the initial diagnoses of AF and HF to randomization and with the onset of AF relative to that of the initial HF diagnosis. In a cohort whose first AF and HF diagnoses were <12 years prior to randomization, in which AF onset did not precede HF by more than 2 years (n = 196), the HR was 0.54 (95% CI: 0.33 to 0.87; p = 0.011). CONCLUSIONS: Pharmacogenetically guided bucindolol therapy did not reduce the recurrence of AF/AFL or ACM compared to that of metoprolol therapy in HFrEF patients, but populations were identified who merited further investigation in future phase 3 trials.

Association between mitochondrial DNA copy number and sudden cardiac death: findings from the Atherosclerosis Risk in Communities study (ARIC).

AIMS: Sudden cardiac death (SCD) is a major public health burden. Mitochondrial dysfunction has been implicated in a wide range of cardiovascular diseases including cardiomyopathy, heart failure, and arrhythmias, but it is unknown if it also contributes to SCD risk. We sought to examine the prospective association between mtDNA copy number (mtDNA-CN), a surrogate marker of mitochondrial function, and SCD risk. METHODS AND RESULTS: We measured baseline mtDNA-CN in 11 093 participants from the Atherosclerosis Risk in Communities (ARIC) study. mtDNA copy number was calculated from probe intensities of mitochondrial single nucleotide polymorphisms (SNP) on the Affymetrix Genome-Wide Human SNP Array 6.0. Sudden cardiac death was defined as a sudden pulseless condition presumed due to a ventricular tachyarrhythmia in a previously stable individual without evidence of a non-cardiac cause of cardiac arrest. Sudden cardiac death cases were reviewed and adjudicated by an expert committee. During a median follow-up of 20.4 years, we observed 361 SCD cases. After adjusting for age, race, sex, and centre, the hazard ratio for SCD comparing the 1st to the 5th quintiles of mtDNA-CN was 2.24 (95% confidence interval 1.58-3.19; P-trend <0.001). When further adjusting for traditional cardiovascular disease risk factors, prevalent coronary heart disease, heart rate, QT interval, and QRS duration, the association remained statistically significant. Spline regression models showed that the association was approximately linear over the range of mtDNA-CN values. No apparent interaction by race or by sex was detected. CONCLUSION: In this community-based prospective study, mtDNA-CN in peripheral blood was inversely associated with the risk of SCD.

Associations of Sex Hormones With Surface Electrocardiogram J Point Amplitude in Healthy Volunteers.

Gender differences in J point height exist. Previous studies suggest male sex hormones mediate effects on cardiovascular disease through myocardial repolarization. Our objective was to assess whether male and female sex hormones are associated with J point amplitude in healthy subjects. We conducted a cross-sectional study of 475 healthy, mixed racial population of men, and premenopausal women (age 33 ± 9 years, 56% male). Baseline J point amplitude (JPA) was obtained from continuous surface electrocardiograms. Plasma testosterone (T), dihydrotestosterone, estrone, 17-estradiol (E2), and sex hormone-binding globulin were measured. A free testosterone index (FTI) was calculated. Multivariate regression analysis stratified by gender and electrocardiographic lead location was used to determine independent predictors of maximum JPA. Regression analysis demonstrated FTI levels were positively associated with JPA in lateral leads (ß = +0.01, p <0.05) in men but not in women. Total testosterone was positively associated with anterior electrocardiographic lead JPA in women (ß = +0.5, p <0.02), but not in men. E2 was positively associated with inferior lead JPA (ß = +1.2, p <0.03) in men but not in women. Total testosterone levels were positively associated with JPA in anterior leads (ß = +0.054, p <0.05) in women. Male volunteers in the highest tertile of FTI demonstrated greater lateral JPA compared with the lowest tertile (p <0.05). Women in the highest tertile of FTI demonstrated greater anterior lead JPA compared with the lowest tertile (p <0.05). In conclusion, in a young, healthy population, the female sex hormone E2 and an FTI are independent determinants of JPA in men, whereas T is associated with JPA in women.

A common SCN5A variant is associated with PR interval and atrial fibrillation among African Americans.

OBJECTIVE: We examined the association of rs7626962 (S1103Y) or rs7629265, a variant in high linkage disequilibrium with S1103Y (r(2) = 0.87 - 1), with sudden cardiac death (SCD) and atrial fibrillation (AF) among African Americans. BACKGROUND: The SCN5A missense variant S1103Y has been associated with SCD among African Americans in small case-control studies, but larger population-based studies are needed to validate these findings. The association of this variant with AF has not been fully explored. METHODS: Using genotyping data on over 7,000 African Americans from 5 cohorts (Atherosclerosis Risk in Communities [ARIC], Cleveland Family Study [CFS], Jackson Heart Study [JHS], Multi-Ethnic Study of Atherosclerosis [MESA], Cardiovascular Health Study [CHS]), we examined the association of rs7629265 with electrocardiographic PR, QRS, and QT intervals, and with incident AF and SCD. We examined association of S1103Y (rs7626962) with SCD using a population-based case-control study of SCD Cardiac Arrest Blood Study (CABS). RESULTS: Meta-analyses across 5 cohorts demonstrated that rs7629265 was significantly associated with PR duration (ß = -4.1 milliseconds; P = 2.2×10(-6) ), but not significantly associated with QRS or QT intervals. In meta-analyses of prospectively followed ARIC and CHS participants (n = 3,656), rs7629265 was associated with increased AF risk (n = 299 AF cases; HR = 1.74, P = 1.9 × 10(-4) ). By contrast, rs7629265 was not significantly associated with SCD risk in ARIC (n = 83 SCD cases; P = 0.30) or CHS (n = 54 SCD cases; P = 0.47). Similarly, S1103Y was not significantly associated with SCD risk in CABS (n = 225 SCD cases; P = 0.29). CONCLUSION: The common SCN5A variant, rs7629265, is associated with increased AF risk and shorter PR interval among African Americans. In contrast to prior reports, we found no evidence of association of rs7629265 or rs7626962 (S1103Y) with SCD risk in the general population.

Clinical characteristics and outcomes associated with the natural history of early repolarization in a young, biracial cohort followed to middle age: the Coronary Artery Risk Development in Young Adults (CARDIA) study.

BACKGROUND: Early repolarization (ER), a common electrocardiographic phenotype, has been associated with increased mortality risk in middle-aged adults. Data are sparse on long-term follow-up and outcomes associated with ER in younger adults. METHODS AND RESULTS: We prospectively examined 5039 participants (mean age, 25 years at baseline, 40% black) from the Coronary Artery Disease Risk in Adults (CARDIA) cohort for 23 years. Twelve-lead ECGs were recorded and analyzed at years 0, 7, and 20 and coded as definite or probable ER using a standardized algorithm. Cox regression was used, and models were adjusted for important baseline and clinical covariates. Kaplan-Meier curves were created for presence of ER and total mortality and cardiovascular mortality. Participants with ER were more likely to be black, male, smoke, have higher systolic blood pressure, lower heart rate and body mass index, higher exercise duration, and longer PR, QRS, and QT intervals. ER was associated with total mortality (hazard ratio, 1.77; confidence interval, 1.38-2.28; P<0.01) and cardiovascular mortality (hazard ratio, 1.59; confidence interval, 1.01-2.50; P=0.04) in unadjusted analyses, but adjustment for age, sex, and race attenuated associations almost completely. Sex-race stratified analyses showed no significant associations between ER and outcome for any of the subgroups except blacks. CONCLUSIONS: The presence of ER at any time point during 23 years of follow-up was not associated with adverse outcomes. Black race and male sex confound the unadjusted association of ER and outcomes, with no race-sex interactions noted. Additional studies are necessary to understand the factors associated with heightened risk of death in those who maintain ER into and beyond middle age.

Sinus arrest following angioplasty and stenting for superior vena cava syndrome.

Superior vena cava (SVC) syndrome is a complication resulting from long-term residence of leads or in-dwelling catheters at the SVC to right atrial (RA) junction. SVC syndrome management is complicated by variable responses to anticoagulation therapies and technically challenging interventional procedures, such as balloon dilatation or stent placement at the SVC-RA junction to relieve blood-flow obstruction. Potential complications resulting from angioplasty/stenting for SVC syndrome are serious and include stent migration, major bleeding, and embolism. Bradyarrhythmias have not been reported. We describe a case of balloon angioplasty and stenting for SVC syndrome in a dialysis patient that resulted in sinus arrest. The complication developed within hours of angioplasty/stenting of her chronic, non-thrombotic SVC obstruction. We highlight the management approach to this patient and discuss potential mechanisms underlying the complication.

Association of the frontal QRS-T angle with adverse cardiac remodeling, impaired left and right ventricular function, and worse outcomes in heart failure with preserved ejection fraction.

BACKGROUND: No prior studies have investigated the association of QRS-T angle with cardiac structure and function and outcomes in heart failure with preserved ejection fraction (HFpEF). The aim of this study was to test the hypothesis that increased frontal QRS-T angle is associated with worse cardiac function and remodeling and adverse outcomes in HFpEF. METHODS: A total of 376 patients with HFpEF (i.e., symptomatic heart failure with left ventricular ejection fraction > 50%) were prospectively studied. The frontal QRS-T angle was calculated from the 12-lead electrocardiogram. Patients were divided into tertiles by frontal QRS-T angle (0°-26°, 27°-75°, and 76°-179°), and clinical, laboratory, and echocardiographic data were compared among groups. Cox proportional-hazards analyses were performed to determine the association between QRS-T angle and outcomes. RESULTS: The mean age of the cohort was 64 ± 13 years, 65% were women, and the mean QRS-T angle was 61 ± 51°. Patients with increased QRS-T angles were older; had lower body mass indices; more frequently had coronary artery disease, diabetes, chronic kidney disease, and atrial fibrillation; and had higher B-type natriuretic peptide levels (P < .05 for all comparisons). After multivariate adjustment, patients with increased QRS-T angles had higher B-type natriuretic peptide levels in addition to higher left ventricular mass indices, worse diastolic function parameters, more right ventricular remodeling, and worse right ventricular systolic function (P < .05 for all associations). QRS-T angle was independently associated with the composite outcome of cardiovascular hospitalization or death on multivariate analysis, even after adjusting for B-type natriuretic peptide (heart rate for the highest QRS-T tertile, 2.0; 95% confidence interval, 1.2-3.4; P = .008). CONCLUSIONS: In HFpEF, increased QRS-T angle is independently associated with worse left and right ventricular function and remodeling and adverse outcomes.

Prognostic value of frontal QRS-T angle in patients without clinical evidence of cardiovascular disease (from the Multi-Ethnic Study of Atherosclerosis).

Abnormal frontal QRS-T angle on a 12-lead electrocardiogram is associated with incident coronary heart disease and total mortality in a biracial cohort, but there have been no studies to date examining QRS-T angle's prognostic value across multiple ethnicities. We studied 6,814 participants (52.7% women, mean age 62 years) from Multi-Ethnic Study of Atherosclerosis, a multiethnic cohort aged 45 to 84 years free of clinical cardiovascular disease (CVD) at enrollment. Baseline examination included measurement of traditional risk factors and 12-lead electrocardiograms. Frontal QRS-T axis was defined as normal (less than seventy-fifth percentile), borderline (seventy-fifth to ninety-fifth percentile), or abnormal (ninety-fifth percentile or more), and participants were followed for the composite end point of incident CVD events: cardiovascular death, myocardial infarction, angina pectoris, or heart failure. After 7.6 years of follow-up, there were 444 total events. Borderline (HR [hazard ratio] 1.37, 95% confidence interval [CI] 1.10 to 1.70) and abnormal QRS-T angles (HR 2.2, 95% CI 1.63 to 2.97) were associated with incident CVD events in multivariate-adjusted models. However, after adjusting for T-wave abnormalities, there was no statistically significant association of either borderline (HR 1.12, 95% CI 0.90 to 1.41) or abnormal (HR 1.31, 95% CI 0.93 to 1.84) QRS-T angle with incident CVD events. Abnormal frontal QRS-T angle predicts incident CVD events in a multiethnic population, and this increased risk is primarily mediated through T-wave abnormalities. QRS-T angle provides an easily interpretable continuous marker of abnormal ventricular repolarization that can aid the everyday clinician in risk prediction.

Natural history of the early repolarization pattern in a biracial cohort: CARDIA (Coronary Artery Risk Development in Young Adults) Study.

OBJECTIVES: The objective of this analysis was to determine the natural history and prospective association of cardiovascular risk factors with early repolarization (ER). BACKGROUND: ER is common and has been suggested to increase risk for cardiovascular mortality in middle-aged adults. Data are sparse regarding the natural history of ER from young adulthood to middle age. METHODS: We examined 5,069 participants (mean age 25 years at baseline; 40% black) from the CARDIA (Coronary Artery Risk Development in Young Adults) cohort over 20 years. Electrocardiograms were recorded at years 0 (Y0), 7 (Y7), and 20 (Y20) and coded as either definite, probable, possible, or no ER. Logistic regression was used to determine the association of cardiovascular risk factors with the presence of ER cross-sectionally and prospectively. RESULTS: A total of 941 of the 5,069 participants (18.6%) had definite ER at baseline, and only 119 of 2,505 participants (4.8%) at the Y20 examination still demonstrated the presence of ER. Younger age, black race, male sex, longer exercise duration and QRS duration, and lower body mass index (BMI), heart rate, QT index, and Cornell voltage were associated cross-sectionally with the presence of ER. Predictors of maintenance of ER from Y0 to Y20 were black race (odds ratio [OR]: 2.62; 95% CI; 1.61 to 4.25), BMI (OR: 0.62 per 1 SD; 95% CI: 0.40 to 0.94), serum triglyceride levels (OR: 0.66 per 1 SD; 95% CI: 0.45 to 0.98), and QRS duration (OR: 1.68 per 1 SD; 95% CI: 1.37 to 2.06) at baseline. CONCLUSIONS: The prevalence of ER was significantly higher than previous estimates among asymptomatic young adults, and the majority of ER regressed by middle age. Black race, lower BMI, lower serum triglyceride levels, and longer QRS duration were independently associated with maintenance of ER over time.

Association of QRS duration with left ventricular structure and function and risk of heart failure in middle-aged and older adults: the Multi-Ethnic Study of Atherosclerosis (MESA).

AIMS: Prolonged QRS duration (QRSd) on the electrocardiogram (ECG) has been associated with cardiac structural and functional abnormalities by echocardiography and an increased risk of heart failure (HF). Data are sparse on these relationships in middle-aged and elderly individuals free of baseline cardiovascular disease with respect to cardiac magnetic resonance imaging (MRI). We sought to determine whether QRSd is associated with incident HF and measures of cardiac structure and function by cardiac MRI. METHODS AND RESULTS: We analysed baseline ECGs in the Multi-Ethnic Study of Atherosclerosis (MESA) to determine whether QRSd >100 ms was associated with incident HF. We adjusted for demographic and clinical risk factors, as well as MRI measures of left ventricular (LV) structure and function. Among 4591 eligible participants (51% women; 39% white; mean age 61 years), 75 developed incident HF over a mean follow-up of 7.1 years. QRSd >100 ms was significantly associated with MRI measures of cardiac structure and function, as well as incident HF, even after adjustment for demographic covariates [hazard ratio (HR) 2.10, 95% confidence interval (CI) 1.29-3.42; P = 0.003] and clinical risk factors (HR 1.86, 95% CI 1.14-3.03; P = 0.01). With further adjustment for individual LV structural measures, findings were attenuated to non-significance. Separate adjustment for LV functional measures yielded only mild attenuation. CONCLUSION: In middle-aged and older adults without cardiovascular disease, a QRSd >100 ms was significantly associated with incident HF. After adjustment for LV structural measures, the association was attenuated to non-significance, suggesting that prolonged QRSd is potentially a useful marker of LV structure that may predispose to HF risk.

Prevalence and predictors of cable extrusion and loss of electrical integrity with the Riata defibrillator lead.

INTRODUCTION: Recently, a medical advisory was issued regarding the Riata and Riata ST silicone endocardial defibrillator leads (St. Jude Medical, Sylmar, CA, USA) addressing the issue of conductor cables extruding in an "inside-out" fashion from the main body of the lead. However, little data exist to guide our management of patients with these leads. METHODS AND RESULTS: A retrospective analysis was performed of 84 patients with a Riata lead who underwent cine-fluoroscopy and electrical evaluation as part of a screening program to assess for cable extrusion. All leads screened were dual-coil except for one single-coil lead. Of 84 patients, 23 patients (27.4%) had fluoroscopic evidence of cable extrusion. Multivariate analysis showed that the duration of time since lead implant and the presence of multiple right ventricular leads were significantly associated with cable extrusion. All 23 patients had normal electrical parameters on routine device interrogation. Fifteen of these 23 patients (65%) with extruded cables had high-voltage shocks within 12 months of lead screening; only one patient demonstrated postshock electrical abnormalities. CONCLUSIONS: The prevalence of cable extrusion in dual-coil Riata leads is significantly higher at 27.4% than previously reported. The duration of time since implantation and the presence of multiple right ventricular leads are associated with cable extrusion. High-energy shocks did not reveal electrical abnormalities in most patients with cable extrusion.