Prognostic value of silent myocardial infarction in patients with chronic kidney disease after kidney transplantation.

We have shown that silent myocardial infarction (SMI) on 12-lead ECG is associated with increased cardiovascular disease (CVD) risk in patients awaiting renal transplantation (RT). In this study, we evaluated the prevalence of SMI in patients undergoing RT and their prognostic value after RT. MI was determined by automated analysis of ECG. SMI was defined as ECG evidence of MI without a history of clinical MI (CMI). The primary outcome was a composite of CVD death, non-fatal MI and coronary revascularization after RT. Of the 1189 patients who underwent RT, a 12-lead ECG was available in >99%. Of the entire cohort 6% had a history of CMI while 7% had SMI by ECG. During a median follow-up of 4.6 years, 147 (12%) experienced the primary outcome (8% CVD death, 4% MI, 4% coronary revascularization) and 12% died. Both SMI and CMI were associated with an increased risk of CVD events and all-cause deaths. In a multivariable adjusted Cox-regression model, both SMI (adjusted hazard ratio 2.03 [1.25-3.30], p = .004) and CMI (2.15 [1.24-3.74], p = .007) were independently associated with the primary outcome. SMI detected by ECG prior to RT is associated with increased risk of CVD events after RT.

New atrial fibrillation diagnosed by 30-day rhythm monitoring.

BACKGROUND: Recent studies of patients with pacemakers and implantable cardioverter/defibrillators have shown that subclinical atrial fibrillation (AF) is common and is associated with thromboembolic risk. We sought to evaluate the frequency, characteristics, and impact of new AF diagnosed by ambulatory 30-day rhythm monitoring. METHODS: The 30-day rhythm monitoring data from January 2010 to August 2015 at our institution were reviewed. Medical record review was performed on patients that had a new or preexisting diagnosis of AF. RESULTS: Of 2,326 patients without a previous diagnosis of AF, 78 had a new diagnosis of AF (3.4%) during 30-day monitoring. Patients with a new diagnosis of AF (mean age of 68.5 years, 56% female) had a mean CHA2DS2-VASc score of 3.2 (±1.8). The median time to diagnosis was 6 days, and 86% were diagnosed within 14 days. In 31 patients (40%), AF was exclusively detected automatically by the monitor. Of 46 patients that had manually activated the monitor, 34 also had automatically detected AF. Each patient had a median of 7 episodes, with the median duration of the longest episode being approximately 2 hours. Following the diagnosis of AF, 37 (47%) were started on anticoagulation and 9 (12%) were prescribed aspirin. CONCLUSIONS: A total of 3.4% of patients who underwent 30-day rhythm monitoring for any indication were found to have a new diagnosis of AF (402 per 1000 patient-years). Most of these episodes were detected automatically, corresponding to device-detected subclinical AF. The most common intervention following diagnosis of AF was initiation of oral anticoagulation.

Subclinical atrial fibrillation detection with a floating atrial sensing dipole in single lead implantable cardioverter-defibrillator systems: Results of the SENSE trial.

INTRODUCTION: Subclinical atrial fibrillation (AF), in the form of cardiac implantable device-detected atrial high rate episodes (AHREs), has been associated with increased thromboembolism. An implantable cardioverter-defibrillator (ICD) lead with a floating atrial dipole may permit a single lead (DX) ICD system to detect AHREs. We sought to assess the utility of the DX ICD system for subclinical AF detection in patients, with a prospective multicenter, cohort-controlled trial. METHODS AND RESULTS: One hundred fifty patients without prior history of AF (age 59 ± 13 years; 108 [72%] male) were enrolled into the DX cohort and implanted with a Biotronik DX ICD system at eight centers. Age-, sex-, and left ventricular ejection fraction-matched single- and dual-chamber ICD cohorts were derived from a Cornell database and from the IMPACT trial, respectively. The primary endpoint were AHRE detection at 12 months. During median 12 months follow-up, AHREs were detected in 19 (13%) patients in the DX, 8 (5.3%) in the single-chamber, and 19 (13%) in the dual-chamber cohorts. The rate of AHRE detection was significantly higher in the DX cohort compared to the single-chamber cohort (P = .026), but not significantly different compared to the dual-chamber cohort. There were no inappropriate ICD therapies in the DX cohort. At 12 months, only 3.0% of patients in the DX cohort had sensed atrial amplitudes less than 1.0 mV. CONCLUSION: Use of a DX ICD lead allows subclinical AF detection with a single lead DX system that is superior to that of a conventional single-chamber ICD system.

Incidence of atrioventricular block with vasodilator stress SPECT: A meta-analysis.

BACKGROUND: Adenosine or regadenoson are often used with pharmacologic stress testing. Adenosine may trigger atrioventricular block (AVB). Despite its higher selectivity, regadenoson has also been associated with AVB. We studied the incidence of de novo AVB with these agents. METHODS: A comprehensive search of SCOPUS was performed from inception to March 2016. Studies of at least 10 patients, using adenosine and/or regadenoson with SPECT-MPI, reporting rates of AVB were selected for further review. RESULTS: Thirty four studies were pooled including 22,957 patients. Adenosine was used in 21 studies and regadenoson in 15. Both were administered in two studies. The estimated incidence of overall and high-grade AVB was 3.81% (95% CI 1.99%-6.19%) and 1.93% (95% CI 0.77%-3.59%), respectively. The incidence of AVB (8.58%; 95% CI 5.55%-12.21% vs 0.30%; 95% CI 0.04%-0.82%, respectively, P < .001) and high-grade AVB (5.21%; 95% CI 2.81%-8.30% vs 0.05%; 95% CI < .001%-0.19% respectively, P < .001) were higher with adenosine compared to regadenoson. CONCLUSION: AVB is seen in about 4% of patients undergoing vasodilator stress test. Both overall and high-grade AVB are more frequent with adenosine compared to regadenoson.

Acute Hemodynamic Effects of Biventricular Pacing After Left Ventricular Assist Device.

BACKGROUND: Despite cardiac resynchronization therapy (CRT), some patients with heart failure progress and undergo left ventricular assist device (LVAD) implantation. Management of CRT after LVAD implantation has not been well studied. The purpose of this study was to determine whether RV pacing or biventricular pacing measurably affects acute hemodynamics in patients with an LVAD and a CRT device. METHODS AND RESULTS: Seven patients with CRT and LVAD underwent right heart catheterization. Pressures and oximetry were measured and LVAD parameters were recorded during 3 different conditions: RV pacing alone, biventricular pacing, and intrinsic atrioventricular conduction. Paired t tests were used to evaluate changes within subjects. There were no significant changes in right atrial pressure, pulmonary arterial pressures, pulmonary capillary wedge pressure, cardiac index, or any LVAD parameter (P > .05). CONCLUSIONS: Our data suggest that CRT probably has no acute hemodynamic effect in patients with LVADs, but further study is needed.

Significant Discrepancy Between Estimated and Actual Longevity in St. Jude Medical Implantable Cardioverter-Defibrillators.

BACKGROUND: Real-time estimated longevity has been reported in pacemakers for several years, and was recently introduced in implantable cardioverter-defibrillators (ICDs). OBJECTIVE: We sought to evaluate the accuracy of this longevity estimate in St. Jude Medical (SJM) ICDs, especially as the device battery approaches depletion. METHODS: Among patients with SJM ICDs who underwent generator replacements due to reaching elective replacement indicator (ERI) at our institution, we identified those with devices that provided longevity estimates and reviewed their device interrogations in the 18 months prior to ERI. Significant discrepancy was defined as a difference of more than 12 months between estimated and actual longevity at any point during this period. RESULTS: Forty-six patients with Current/Promote devices formed the study group (40 cardiac resynchronization therapy [CRT] and 6 single/dual chamber). Of these, 34 (74%) had significant discrepancy between estimated and actual longevity (28 CRT and all single/dual). Longevity was significantly overestimated by the device algorithm (mean maximum discrepancy of 18.8 months), more in single/dual than CRT devices (30.5 vs. 17.1 months). Marked discrepancy was seen at voltages ≥2.57 volts, with maximum discrepancy at 2.57 volts (23 months). The overall longevity was higher in the discrepant group of CRT devices than in the nondiscrepant group (67 vs. 61 months, log-rank P = 0.03). CONCLUSIONS: There was significant overestimation of longevity in nearly three-fourths of Current/Promote SJM ICDs in the last 18 months prior to ERI. Longevity estimates of SJM ICDs may not be reliable for making clinical decisions on frequency of follow-up, as the battery approaches depletion.

Mechanisms of sudden cardiac death.

Sudden cardiac death (SCD) continues to be a major public health problem and is thought to account for almost half of all cardiac deaths. Cardiac arrest and SCD are most commonly due to ventricular arrhythmias. Most patients who suffer cardiac arrest have underlying structural heart disease, with coronary artery disease (CAD) being the most common. In the setting of CAD, ventricular arrhythmias can result due to acute ischemia in the absence of preexisting myocardial scarring or in the presence of established scar from prior infarction without clinically significant ischemia. LV systolic dysfunction is an important predictor of risk for SCD in ischemic heart disease and in most nonischemic disorders, although other factors such as ventricular hypertrophy also play a role. Cardiac arrest and SCD can also occur due to primary electrical disorders in the absence of major structural abnormalities.

A novel electrocardiographic criterion for differentiating a left from right ventricular outflow tract tachycardia origin: the V2S/V3R index.

INTRODUCTION: Although several ECG criteria have been proposed for differentiating between left and right origins of idiopathic ventricular arrhythmias (VA) originating from the outflow tract (OT-VA), their accuracy and usefulness remain limited. This study was undertaken to develop a more accurate and useful ECG criterion for differentiating between left and right OT-VA origins. METHODS AND RESULTS: We studied OT-VAs with a left bundle branch block pattern and inferior axis QRS morphology in 207 patients who underwent successful catheter ablation in the right (RVOT; n = 154) or left ventricular outflow tract (LVOT; n = 53). The surface ECGs during the OT-VAs and during sinus beats were analyzed with an electronic caliper. The V2S/V3R index was defined as the S-wave amplitude in lead V2 divided by the R-wave amplitude in lead V3 during the OT-VA. The V2S/V3R index was significantly smaller for LVOT origins than RVOT origins (P < 0.001). The area under the curve (AUC) for the V2S/V3R index by a receiver operating characteristic analysis was 0.964, with a cut-off value of ≤1.5 predicting an LVOT origin with an 89% sensitivity and 94% specificity. In the AUC and accuracy, the V2S/V3R index was superior to any previously proposed ECG criteria in an analysis of all OT-VAs. This advantage of the V2S/V3R index over the V2 transition ratio and other indices also held true for a subanalysis of 77 OT-VAs with a lead V3 precordial transition. CONCLUSION: The V2S/V3R index outperformed other ECG criteria to differentiate left from right OT-VA origins independent of the site of the precordial transition.

Dabigatran versus warfarin therapy for uninterrupted oral anticoagulation during atrial fibrillation ablation.

BACKGROUND: Uninterrupted oral anticoagulant (OA) therapy with warfarin has become the standard of care at many centers performing catheter ablation of atrial fibrillation (AF). Compared with warfarin, dabigatran, a direct thrombin inhibitor, has been demonstrated to reduce the risk of stroke in nonvalvular AF with similar bleeding risk. Few data exist on the safety profile of uninterrupted dabigatran therapy during AF ablation. METHODS: We compared the safety and efficacy of uninterrupted OA therapy with either warfarin or dabigatran in all patients undergoing AF catheter ablation at the University of Alabama at Birmingham between November 1, 2010 and January 31, 2012. All patients underwent a transesophageal echocardiogram (TEE) on the day of their ablation procedure to assess for the presence of intracardiac thrombi. All complications were identified and classified as bleeding, thromboembolic events, or other. RESULTS: There were 212 patients in the dabigatran group and 251 patients in the warfarin group. The groups were well matched. There were 3 complications in the dabigatran group and 6 in the warfarin group (P = 0.45). There were 2 bleeding complications in the dabigatran group and 6 in the warfarin group (P = 0.23). There was one thromboembolic complication (a possible TIA) in the dabigatran group and none in the warfarin group (P = 0.28). CONCLUSION: The administration of dabigatran is as safe and effective as warfarin for uninterrupted OA therapy during catheter ablation of AF.

Cardiovascular implantable electronic device implantation with uninterrupted dabigatran: comparison to uninterrupted warfarin.

BACKGROUND: While continuation of oral anticoagulation (OAC) with warfarin may be preferable to interruption and bridging with heparin for patients undergoing cardiovascular implantable electronic device (CIED) implantation, it is uncertain whether the same strategy can be safely used with dabigatran. OBJECTIVE AND METHODS: To determine the risk of bleeding and thromboembolic complications associated with uninterrupted OAC during CIED implantation, replacement, or revision, the outcomes of patients receiving uninterrupted dabigatran (D) were compared to those receiving warfarin (W). RESULTS: D was administered the day of CIED implant in 48 patients (age 66 ± 12.4 years, 13 F and 35 M, 21 ICDs and 27 PMs), including new implant in 25 patients, replacement in 14 patients, and replacement plus lead revision in 9 patients. D was held the morning of the procedure in 14 patients (age 70 ± 11 years, 4 F and 10 M, 5 ICDs and 9 PMs). W was continued in 195 patients (age 60 ± 14.4 years, 54 F, and 141 M), including new implant in 122 patients, replacement in 33 patients, and replacement plus lead revision or upgrade in 40 patients. Bleeding complications occurred in 1 of 48 patients (2.1%) with uninterrupted dabigatran (a late pericardial effusion), 0 of 14 with interrupted D, and 9 of 195 patients (4.6%) on W (9 pocket hematomas), P = 0.69. Fifty percent of bleeding complications were associated with concomitant antiplatelet medications. CONCLUSIONS: The incidence of bleeding complications is similar during CIED implantation with uninterrupted D or W. The risks are higher when OAC is combined with antiplatelet drugs.

Idiopathic mitral annular PVCs with multiple breakouts and preferential conduction unmasked by radiofrequency catheter ablation.

A 39-year-old man with idiopathic monomorphic premature ventricular contractions (PVCs), exhibiting a right bundle branch block and inferior axis QRS morphology, underwent electrophysiological testing. After a radiofrequency (RF) application to the anterior mitral annulus (MA) eliminated the spontaneous PVC morphology, a second PVC morphology occurred. Pacing from the first ablation site exhibited an excellent match to the second PVCs with a long stimulus to QRS interval. An RF application delivered near the first lesion eliminated all PVCs. The MA PVCs in this case exhibited a single origin with multiple breakouts and preferential conduction that were unmasked by RF ablation.

Epicardial macroreentrant ventricular tachycardia associated with a left ventricular aneurysm.

A 62-year-old man with severe coronary artery disease and a left ventricular aneurysm underwent catheter ablation of ventricular tachycardia (VT) with right bundle branch block QRS morphology. Endocardial bipolar voltage mapping with standard threshold settings demonstrated no low-voltage areas within the aneurysm. Catheter ablation of the epicardial surface of the aneurysm eliminated the VT. Endocardial bipolar voltage mapping with any other settings could not predict the site of the epicardial arrhythmogenic substrate whereas endocardial unipolar voltage mapping could. Endocardial unipolar voltage mapping may be helpful for predicting epicardial arrhythmogenic substrates.

Idiopathic premature ventricular contractions arising from the intraventricular septum adjacent to the his bundle.

A 57-year-old woman with idiopathic premature ventricular contractions (PVCs) exhibiting a left bundle branch block and left inferior axis QRS morphology underwent electrophysiological testing. Mapping revealed that the earliest ventricular activation times during the PVCs recorded on either side of the interventricular septum were the same and no excellent pace maps were reproduced at these sites. Successful radiofrequency catheter ablation was achieved in the right ventricular septum adjacent to the recording site of the His bundle electrogram. These findings suggested that the origin of this PVC was located in the intraventricular septum rather than the endocardial surface.

Successful reduction of a high defibrillation threshold by a combined implantation of a subcutaneous array and azygos vein lead.

A 72-year-old man with nonischemic cardiomyopathy was referred because his implantable cardioverter defibrillator had failed to terminate spontaneous ventricular fibrillation (VF). Defibrillation threshold (DFT) testing confirmed that 830-V shocks failed to defibrillate VF despite optimization of the biphasic waveform and reversal of shock polarity. The placement of a new right ventricular lead and the addition of a subcutaneous array failed to defibrillate VF at 830 V. The combination of a subcutaneous array and azygos vein coil successfully defibrillated VF. The mechanism for successful DFT reduction was likely greater current supplied to the posterior basal left ventricle by the azygos vein lead.