History Of Ventricular Tachyarrhythmias Research Articles

Reduction in Ventricular Tachyarrhythmia Burden in Patients Enrolled in the RAIDTrial.

The RAID (Ranolazine Implantable Cardioverter-Defibrillator) randomized placebo-controlled trial showed that ranolazine treatment was associated with reduction in recurrent ventricular tachycardia (VT) requiring appropriate implantable cardioverter-defibrillator (ICD) therapy. This study aimed to identify groups of patients in whom ranolazine treatment would result in the highest reduction of ventricular tachyarrhythmia (VTA) burden. Andersen-Gill analyses were performed to identify variables associated with risk for VTA burden among 1,012 patients enrolled in RAID. The primary endpoint was VTA burden defined as VTA episodes requiring appropriate treatment. Multivariate analysis identified 7 factors associated with increased VTA burden: history of VTA, age≥65 years, New York Heart Association functional class≥III, QRS complex (≥130ms), low ejection fraction (<30%), atrial fibrillation (AF), and concomitant antiarrhythmic drug (AAD) therapy. The effect of ranolazine on VTA burden was seen among patients without concomitant AAD therapy (HR [HR]: 0.68; 95%CI: 0.55-0.84; P< 0.001), whereas no effect was seen among those who are concomitantly treated with other AADs (HR: 1.33; 95%CI: 0.90-1.96; P = 0.16); P = 0.003 for interaction. In patients with cardiac resynchronization therapy (CRT) ICDs, ranolazine treatment was associated with a 36% risk reduction for VTA recurrence (HR: 0.64; 95%CI: 0.47-0.86; P< 0.001), whereas among patients with ICDs without CRT no significant effect was noted (HR: 0.94; 95%CI: 0.74-1.18; P = 0.57); P = 0.047 for interaction. In patients with high risk for VTA, ranolazine is effective in reducing VTA burden, with significantly greater effect in CRT-treated patients, those without AF, and those not treated with concomitant AADs. In patients already on AADs or those with AF, the addition of ranolazine did not affect VTA burden. (Ranolazine Implantable Cardioverter-Defibrillator Trial [RAID]; NCT01215253).

Safety of Outpatient Milrinone Infusion in End-Stage Heart Failure: ICD-Level Data on Atrial Fibrillation and Ventricular Tachyarrhythmias

Milrinone infusion is one of a few select "non-device" therapies for patients with New York Heart Association (NYHA) class IV, stage D heart failure, which has been associated with an increase in ventricular tachyarrhythmia and atrial fibrillation. Milrinone improves hemodynamics and provides symptomatic relief. Many patients with end-stage heart failure die from cardiac pump failure, and the impact of ventricular tachyarrhythmia and atrial fibrillation on their mortality is unclear. This is a retrospective study of 98 consecutive patients receiving outpatient milrinone in a single center from 2008 to 2016. The primary endpoint of the study was overall survival on milrinone. Secondary endpoints were incidence of post-milrinone implantable cardioverter defibrillator (ICD) shocks and development of ventricular tachyarrhythmia or atrial fibrillation. Median survival was 581 ± 96 days with no difference between those with prior ventricular tachyarrhythmia and those without at 1 month (92% vs 97%, P=0.34), 6 months (67% vs 73%, P=0.75), and 12 months (67% vs 61%, P=0.88). Seven out of 12 (58%) patients with prior ventricular tachyarrhythmia had ICD shocks, as compared to 5 out of 78 (6.4%) (P <0.001). Thirty-five patients had atrial fibrillation prior to starting milrinone, which decreased to 72% (P <0.05) by the third follow-up time period (7-9 months). Amiodarone use was protective against new onset atrial fibrillation. Patients with stage D heart failure with a history of ventricular tachyarrhythmia have similar survival on outpatient milrinone compared to those without. However, those with prior ventricular tachyarrhythmia received more ICD shocks for more ventricular tachyarrhythmias. Milrinone remains a viable therapy for patients with stage D heart failure with limited therapeutic options.

The role of entirely subcutaneous ICD™ systems in patients with dilated cardiomyopathy

BackgroundThe subcutaneous implantable-cardioverter defibrillator (S-ICD™, Boston Scientific, Natick, MA, USA) is an important advance in device therapy for the prevention of sudden cardiac death (SCD). Although current guidelines recommend S-ICD™ use, long-term data are still limited, especially in subgroups. Dilated cardiomyopathy (DCM) is a common reason for the implantation of an ICD. However, there are no sufficient data on the performance of the S-ICD™ in this patient cohort. Materials and methodsAll S-ICD™ patients with DCM as the main indication for ICD implantation (n=47 patients) in our large-scaled single-center S-ICD™ registry (n=294 patients) were included in this study. Baseline characteristics, appropriate and inappropriate shocks, and complications were documented in a mean follow-up of 22.9±18.5 months. ResultsA total of 47 patients with DCM as the underlying structural heart disease received an S-ICD™ in our institution. Mean left ventricular ejection fraction was 37±12% and a 28% had a history of ventricular tachyarrhythmia. During follow-up eight ventricular tachyarrhythmias were adequately terminated in three patients. In four patients, oversensing resulting in an inappropriate shock was observed, which could be managed by changing the sensing vector. There was no need for a change to a cardiac resynchronization (CRT) system while one system was changed to a VVI-ICD due to S-ICD™ wound infection. ConclusionThe S-ICD™ seems to be a valuable option for the prevention of SCD in patients with DCM and no indication for CRT. As clinically relevant ventricular arrhythmias consisted of ventricular fibrillation or fast ventricular tachycardia in all patients in our cohort, no change to transvenous ICDs for anti-tachycardia pacing delivery was necessary.

Relationship between Extension or Texture Features of Late Gadolinium Enhancement and Ventricular Tachyarrhythmias in Hypertrophic Cardiomyopathy.

Purpose To evaluate the relationship between extension or texture features of late gadolinium enhancement (LGE) and ventricular tachyarrhythmias in hypertrophic cardiomyopathy (HCM). Materials and Methods Twenty-three patients with HCM were enrolled in this IRB-approved study. The extension of LGE was determined based on the American Heart Association segments model. Texture analysis was performed for 43 myocardial LGE using an open-access software (MaZda, Technical University of Lodz, Institute of Electronics, Poland). The relationship between the extension or texture features of LGE and ventricular tachyarrhythmias was evaluated using unpaired test and receiver-operating characteristic (ROC) analysis. Results Six of 23 patients had a history of ventricular tachyarrhythmias, and 16 patients had LGE. All of the 6 patients with the arrhythmias had more than 4 LGE segments and more LGE segments than those without (p < 0.01). Among 4 texture features, entropy LL was the only discriminator between the 2 patient groups (p < 0.01; threshold, 19624; area under the curve [AUC], 0.72). An ROC analysis gave the number of segments showing LGE a better result (AUC, 0.96) for identification of HCM patients with ventricular tachyarrhythmias than the entropy LL of LGE. Conclusion Patients with HCM and a history of ventricular tachyarrhythmias had a wider extension of LGE, and their entropy LL of LGE was significantly lower than those without. The extension of LGE and texture analysis may provide information about LGE related to ventricular tachyarrhythmias in HCM.

Incidence, Risk Factors, and Outcome of Life-Threatening Ventricular Arrhythmias in Giant Cell Myocarditis.

Ventricular tachyarrhythmias are characteristic of giant cell myocarditis, but their true incidence, predictors, and outcome are unknown. Our work involved 51 patients with giant cell myocarditis (35 women) aged 52±12 years. Their medical records were reviewed for history, results of laboratory and imaging studies, and occurrence of serious cardiac events, including life-threatening ventricular tachyarrhythmias. Sudden cardiac death (fatal or aborted) was the primary end point of our analyses, whereas the composite of sudden cardiac death and ventricular tachycardia requiring treatment constituted the secondary end point. Giant cell myocarditis presented as nonfatal ventricular tachyarrhythmia in 10 patients and as a fatal cardiac arrest in 1 patient. Overall, 14 of 50 patients suffered a sudden cardiac death during follow-up, with a cumulative incidence of 22% at 1 year and 26% at 5 years from presentation. The composite incidence of sudden cardiac death or ventricular tachycardia was 41% at 1 year and 55% at 5 years. The incidence of arrhythmias was associated with high plasma concentrations of troponin-T and N-terminal brain natriuretic propeptide, as well as with moderate-to-severe fibrosis on myocardial biopsy and history of ventricular tachyarrhythmias at presentation (P<0.05 for all). An intracardiac cardioverter defibrillator was implanted in 31 patients, of whom 17 had altogether 114 appropriate antiarrhythmic therapies by the device and none suffered an arrhythmic death. In giant cell myocarditis, the risk of life-threatening ventricular arrhythmias exceeds 50% at 5 years from admission, being related to the presenting clinical manifestation and markers of myocardial injury and scarring.

Predictors and clinical relevance of ventricular tachyarrhythmias in ambulatory patients with a continuous flow left ventricular assist device

Patients with a left ventricular assist device (LVAD) are at high risk for ventricular tachyarrhythmias (VTAs). We aimed to identify clinical predictors of VTAs and subsequent outcomes after VTA in ambulatory LVAD patients. A retrospective study of 149 patients with a continuous flow HeartMate II LVAD who survived to discharge from index hospitalization after LVAD implantation was performed from January 10, 2005, to September 3, 2013. A multivariate Cox model was used to assess clinical predictors of VTAs. During a mean follow-up period of 2.1 ± 1.2 years, 41 patients (28%) experienced VTAs; 30 of these patients (71%) had ventricular tachycardia, and 11 (29%) had ventricular fibrillation. History of VTAs before LVAD (hazard ratio [HR] 3.06; 95% confidence interval [CI] 1.57-5.96; P = .001) and history of atrial fibrillation (AF) (HR 3.13; 95% CI 1.60-6.11; P = .008) were the most powerful predictors of VTAs after LVAD implantation. There were 19 deaths (46%) among patients with VTAs and 15 deaths (14%) among patients without VTAs (P < .001). In multivariate analysis, time-dependent VTAs after LVAD implantation were associated with a significantly higher risk of all-cause mortality when compared with those without VTAs (HR 7.28; 95% CI 3.50-15.15; P < .001). In ambulatory LVAD patients, history of VTAs before LVAD implantation and history of AF predict VTAs after LVAD implantation. VTAs are associated with an increased risk of mortality. In such patients, aggressive measures to control VTAs and AF should be considered.

Abstract 12168: Risk Stratification for Ventricular Tachyarrhythmias in Patients With Cardiac Sarcoidosis by Cardiac Magnetic Resonance Imaging

Introduction: Recently, late gadolinium-enhancement (LGE) cardiac magnetic resonance (CMR) imaging, which has been used to uniquely characterize the myocardial fibrosis, is reported to have a prognostic value in cardiac sarcoidosis (CS) Hypothesis: Not only fibrosis mass, but also its localization may help to identify the risk of ventricular tachyarrhythmias (VA) in patients with CS. Methods: 70 consecutive CS patients underwent CMR (cine and LGE imaging). Left ventricular (LV) mass and fibrosis mass were calculated and the localization was analyzed using 17 segment model. VA was defined as sustained ventricular beats ≥ 3 or ventricular fibrillation. The patients underwent prospective follow-up through 2015 from CMR examinations. Results: 33.3 % of the patients had a history of VA at the time of CMR examination. During a median follow-up of 15.5 months, 31.9 % had new-onset (11.6 %) or recurrent VA (20.3 %). Increased LV fibrosis mass (LVFM) was associated with the prevalence of VA (P &lt; 0.001) and receiver operating characteristics curve analysis indicated good predictive performance of LVFM for the combined VA (history of VA and new-onset VA) (AUC = 0.788, best cut-off value; 8.28 g). In addition, when localization score (LS) was defined as the summation of LGE enhancement in LV basal anterior, basal anteroseptal, or RV out-flow tract (RVOT) lesion, it was associated with the combined VA (P &lt; 0.001). Kaplan-Meier analysis showed that both LVFM and LS groupings were significantly associated with VA occurrence (Figure A). Furthermore, a combined analysis of LVFM and LS groups showed a better risk stratification for VA (Figure B). Conclusions: Not only fibrosis mass, but also its localization of basal anterior, anteroseptal, or RVOT was associated with the history of VA as well as the prognosis for VA in patients with CS. CMR may be a useful tool for risk stratification for ventricular tachyarrhythmias by detecting myocardial fibrosis and localization in CS patients.

Abstract 8158: Prior Incidence of Ventricular Tachyarrhythmias Predict Subsequent Episodes of Ventricular Tachyarrhythmias and Increased Mortality in Subjects with Mildly Reduced Ejection Fraction on Cardiac Resynchronization Therapy -A MADIT study analysis

Background: An incidence of ventricular tachyarrhythmia (VA)(including ventricular tachycardia and ventricular fibrillation) in a patient with reduced ejection fraction is a marker of increased all-cause mortality. We aimed to assess the impact of prior VAs on clinical outcomes in patients with mild heart failure symptoms who received cardiac resynchronization therapy with a defibrillator (CRT-D). Methods: We evaluated benefit of CRT-D vs. ICD-only therapy in the reduction of ventricular tachyarrhythmias or death by the presence of a history of VA among 1820 patients enrolled in the MADIT-CRT trial. Results: A history of VA was a significant risk factor for the occurrence of VT/VF or death during the trial (HR 2.06, 95% CI 1.55-2.74, p&lt;0.001). Multivariate analysis showed that CRT-D therapy was associated with a significant reduction in the risk of ventricular tachyarrhytmias among patients without a history of VA, whereas risk-reduction associated with CRT-D therapy was not statistically significant among patients with a history of prior VA (Table). Conclusions: Our findings suggest that a history of prior VA is a powerful risk factor for the development of subsequent ventricular tachyarrhythmias and mortality among patients with mild CHF symptoms who receive device therapy. The benefit of CRT-D therapy appears to be attenuated among patients with prior VA.

Comparison of Ventricular Tachyarrhythmia Characteristics in Patients With Idiopathic Dilated or Ischemic Cardiomyopathy and Defibrillators Implanted for Primary Prevention

Implantable cardioverter-defibrillator (ICD) therapy for primary prevention is well established in ischemic cardiomyopathy (ICM). Data on the role of ICDs in patients with dilated cardiomyopathy (DCM) and no history of ventricular tachyarrhythmia (VT/VF) are more limited. DCM patients with an impaired left ventricular ejection fraction (LVEF) still represent a low arrhythmic risk subgroup in clinical practice. ICD stored data of DCM patients with an LVEF ≤35% was compared to data of ICM patients meeting Multicenter Automatic Defibrillator Implantation Trial (MADIT) eligibility criteria. VT/VF occurrences and electrical storm (ES) events were analyzed. There were 652 patients followed for 50.9 ± 33.9 months. There were 1978 VT and 241 VF episodes analyzed in 66 out of 203 patients (32.5%) with DCM and in 118 out of 449 patients (26.3%, P = 0.209) with ICM. Freedom of appropriate ICD treatment due to VT/VF or ES events did not differ in both patient populations (log-rank, P>0.05). In patients presenting with VT/VF episodes, mean event rates were comparable in both patient populations (3.2 ± 14.1 for DCM and VT vs 3 ± 13.9 for ICM and VT [P = 0.855], 0.4 ± 1.3 for DCM and VF vs 0.4 ± 1.8 for ICM and VF [P = 0.763], and 0.2 ± 0.7 for DCM and ES vs 0.2 ± 1 for ICM and ES [P = 0.666]). DCM patients with prophylactic ICDs implanted due to heart failure and patients fulfilling MADIT criteria reveal comparable patterns of VT/VF/ES events during long-term follow-up. Incidence, mean number of events, and time to first event did not differ significantly. Findings support the current guidelines for prophylactic ICD therapy in DCM patients with heart failure.

Are complications of implantable defibrillators under-estimated and benefits over-estimated?

> It is ethically imperative that we are aware of the data, so that we can be honest with our patients . In a systematic review1 of 12 randomized controlled trials (RCTs) accounting for a total of 8516 patients with left ventricular (LV) systolic dysfunction (regardless of whether the patients had heart failure symptoms), 86% of whom had New York Heart Association (NYHA) class II or III symptoms, implantable cardioverter defibrillators (ICDs) reduced all-cause mortality by 20% (95% CI, 10–29); the reduction in total mortality was largely due to a 54% relative reduction of sudden death. In the same review, ICDs reduced all-cause mortality by 46% (95% CI, 32–57) in 11 observational cohort studies with contemporaneous control groups for a total of 9450 patients. In the observational studies, the mean left ventricular ejection fraction (LVEF) ranged from 0.19 to 0.46. The observational studies demonstrated a reduced frequency of non-cardiac death in ICD recipients (RR, 0.74). The fact that the controlled observational studies demonstrated a reduced frequency of non-cardiac death in ICD recipients suggests that clinicians select healthier patients for ICD insertion, and this probably accounts for the larger apparent benefit from ICDs on all-cause mortality in observational studies than in RCTs. This beneficial effect exists regardless of whether a patient has a history of haemodynamically apparent ventricular arrhythmias (primary or secondary prevention) or an ischaemic cause. However, in RCTs, LVEF ranged from 0.21 to 0.28 in the primary prevention trials and from 0.32 to 0.46 in the secondary prevention trials. While there was a definite survival benefit in patients with a history of ventricular tachyarrhythmias (HR = 0.77 [95% CI 0.65–0.91)] and in those in NYHA class II or III (HR = 0.81 [95% CI 0.69–0.95]), a post hoc meta-regression using aggregate trial data from 12 RCTs showed no significant … *Corresponding author. Tel: +39 0185 329 567, Fax: +39 0185 306 506, Email: mbrignole{at}ASL4.liguria.it

The Significance of Cardiac Sympathetic Nervous System Abnormality in the Long-Term Prognosis of Patients with a History of Ventricular Tachyarrhythmia

Severe left ventricular dysfunction or cardiac sympathetic nervous system (SNS) abnormality predicts cardiac death in various heart diseases, including arrhythmogenic disorders. However, it is not clear whether SNS abnormality predicts sudden cardiac death during long-term follow-up in patients with a history of ventricular tachyarrhythmia. We hypothesized that SNS abnormality would be associated with recurrent ventricular arrhythmic events. 123I-metaiodobenzylguanidine (MIBG) scintigraphy was performed on 86 patients (mean age+/-SD, 46+/-19 y, 65.1% men) with a history of ventricular tachycardia or fibrillation. 123I-MIBG (111 MBq) was intravenously administered under resting conditions, and planar images were obtained 15 min and 4 h later (anterior view for 6 min; 512x512 matrices; zoom ratio, 1.0). SNS activity was assessed using the heart-to-mediastinum ratio on delayed imaging. During about 11 y of follow-up (mean+/-SD, 5.2+/-3.7 y), 3 patients (3.5%) had sudden cardiac death and 21 patients (24.4%) had sustained ventricular tachyarrhythmic events. SNS abnormality, defined as a heart-to-mediastinum ratio of less than 2.8, and left ventricular dysfunction, defined as a left ventricular ejection fraction of less than 50%, were associated with sudden cardiac death or recurrent ventricular tachyarrhythmic events (18/40 patients [45%] with SNS abnormality, vs. 6/46 patients [13%] without, P=0.004; 9/15 patients [60%] with left ventricular dysfunction, vs. 15/71 patients [21.1%] without, P=0.008). After adjustment for potential confounding variables such as age, sex, coronary risk factors, medication use, history of structural heart disease, and left ventricular function, SNS abnormality was a powerful predictor of recurrent arrhythmic events, with a hazard ratio of 3.6 [95% confidence interval, 1.4-9.2, P=0.007]). Further, SNS abnormality had incremental and additive prognostic power in combination with left ventricular dysfunction, with an adjusted hazard ratio of 4.4 [95% confidence interval, 1.9-9.9, P<0.0001]). SNS abnormality predicted recurrent ventricular tachyarrhythmic events during long-term follow-up. 123I-MIBG scintigraphic evaluations for SNS abnormality may be an option for screening patients at high risk for sudden cardiac death.

Clinical experience with implantable atrial and combined atrioventricular defibrillators.

The high prevalence of atrial fibrillation (AF) and its clinical complications, the poor efficacy of medical therapy for preventing recurrences, and dissatisfaction with alternative modes of therapy stimulated interest in implantable atrial and combined atrioventricular defibrillators. In a multicenter study, the safety and efficacy of a stand alone implantable atrial defibrillator, the Metrix system, were evaluated. The device was implanted in 51 patients with highly symptomatic episodes of AF refractory to pharmacological treatment. During a follow-up of 9 months, 96% of 227 spontaneous AF episodes were successfully converted to sinus rhythm in 41 patients. In 62 episodes (27%), several shocks and/or additional drug treatment were required to maintain stable sinus rhythm because of early recurrences of AF. A total of 3719 shocks were delivered and no induction of ventricular proarrhythmia or inaccurately synchronized shocks occurred. The AF detection algorithm exhibited a 100% specificity for the recognition of sinus rhythm and a 92.3% sensitivity for the detection of AF. The combined atrioventricular defibrillator, Jewel AF 7250, was evaluated in a multicenter, randomized, cross-over trial. The primary study objectives included: overall safety as determined by complications-free survival at 6 months, efficacy of tiered atrial pacing and defibrillation therapies for termination of spontaneous atrial tachycardias (AT) and AF, and relative sensitivity of a new dual-chamber detection algorithm. The device was implanted in 211 patients with either a history of ventricular tachyarrhythmias (VT/VF) alone or with a history of both AT/AF and VT/VF. During a mean follow-up of 4.5 months, it has been shown that the Jewel AF is safe and effective in treating atrial and ventricular tachyarrhythmias. Pace termination of 85% of AT episodes were achieved with painless delivery of antitachycardia pacing; additional 35% of AT episodes were terminated by high frequency burst pacing. The stand alone implantable atrial defibrillator may be safe and clinically useful in selected patients for the treatment of highly symptomatic, drug resistant recurrences of AF. The combined atrioventricular defibrillator may be particularly indicated in patients presenting with both a history of atrial and ventricular tachyarrhythmias.

Amiodarone Reduces the Prevalence of T Wave Alternans in a Population with Ventricular Tachyarrhythmias

Testing for the presence of microvolt T wave alternans (TWA) is useful for arrhythmic risk stratification. Whether antiarrhythmic pharmacotherapy affects the presence of TWA is unknown. We tested whether patients with known ventricular tachyarrhythmias who were receiving amiodarone were less likely to manifest TWA as compared with those not receiving amiodarone. Forty-four patients with a history of ventricular tachyarrhythmias and an implantable cardioverter defibrillator (ICD) implanted at least 1 month earlier underwent TWA testing. In this group, 14 patients were receiving amiodarone and 30 were not. Indeterminate test results occurred in 13 patients without a significant difference in those receiving or not receiving amiodarone. In the 31 patients with determinate TWA testing, a positive test was less likely in those receiving amiodarone (1 of 9 [11%]) as compared with those not receiving amiodarone (14 of 22 [64%]; P = 0.04). During a follow-up period averaging 0.9 +/- 0.2 years, the presence of TWA (P = 0.04) and decreased left ventricular ejection fraction (P = 0.05) predicted appropriate ICD therapy for ventricular tachyarrhythmias. The prevalence of TWA was decreased in a chronic ventricular tachyarrhythmic population receiving amiodarone as compared with a population not receiving amiodarone.

Standard 12‐Lead and 24‐Hour Ambulatory Electrocardiographic Abnormalities in Survivors of Tachyarrhythmic Cardiac Arrest

BackgroundThe aim of the present work was to compare the accuracies of variables obtained from a standard 12‐lead ECG and a 24‐hour ambulatory ECG in discriminating between patients with and patients without tachyarrhythmic cardiac arrest after a previous myocardial infarction.MethodsQTc interval and QTc dispersion measured from a 12‐lead ECG and an analysis of ventricular premature depolarization, nonsustained ventricular tachycardia, and heart rate variability from a 24‐hour ECG were compared in survivors of tachyarrhythmic cardiac arrest (n = 57) and in postmyocardial infarction control patients without a history of arrhythmic events and an arrhythmic‐free survival in a 2‐year follow‐up (n = 57). The groups were matched for age, gender, left ventricular ejection fraction, and the usage of beta‐blocking medication.ResultsQTc dispersion (103 ± 44 vs 71 ± 32 ms, P &lt; 0.001) and the QTc interval maximum, defined as the longest QTc interval in any of the 12 leads of ECG (508 ± 52 vs 459 ± 42 ms, P &lt; 0.001), were longer in the cardiac arrest survivors than in the controls. The standard deviation of R‐R intervals, a measure of heart rate variability, was lower in the cardiac arrest survivors (86 ± 38 vs 108 ± 32 ms, P &lt; 0.001), who had also experienced more commonly ≥; 10 ventricular premature depolarizations/hour (61% vs 35%, P &lt; 0.01) on the 24‐hour ECG. In a stepwise multiple regression analysis, the QTc interval maximum and the standard deviation of R‐R intervals were the most significant independent variables that differed between the groups (P = 0.0002, P = 0.0023, respectively). Their combination yielded a high positive predictive accuracy (91%).ConclusionsSimple measurement of the maximum QTc interval from a standard 12‐lead ECG performs equally well or even better than the other more time‐consuming 12‐lead or 24‐hour ambulatory ECG variables in discriminating between patients with a history of tachyarrhythmic cardiac arrest and patients without a history of ventricular tachyarrhythmias after a remote myocardial infarction.

Postextrasystolic U Wave Augmentation, a New Marker of Increased Arrhythmic Risk in Patients Without the Long QT Syndrome

We attempted to determine the correlation between the presence of postextrasystolic changes in the STU segment and a history of sustained ventricular arrhythmias. Postextrasystolic U wave augmentation (a marked increment in U wave amplitude after premature ventricular complexes [PVCs]) is an adverse prognostic sign in the "pause-dependent long QT syndrome." However, the prevalence of postextrasystolic changes in patients without the long QT syndrome is unknown. We compared the configuration of the STU segment of the postextrasystolic beat (the sinus beat after a PVC) with the STU configuration during sinus rhythm in three patient groups: 1) 41 patients with spontaneous ventricular tachycardia/fibrillation (VT/VF) (VT/VF group), 2) 63 patients with heart disease and high grade ventricular arrhythmias (control group), and 3) 29 patients with high grade ventricular arrhythmias but no heart disease (reference group). Postextrasystolic T wave changes did not correlate with a history of ventricular tachyarrhythmias. However, postextrasystolic U wave changes were more common among the patients with VT/VF than among control subjects (39% vs. 8.7%, p < 0.001). By logistic multiple regression analysis, a low left ventricular ejection fraction (p < 0.001) and postextrasystolic U wave changes (p < 0.005) were independent predictors of ventricular tachyarrhythmias. Postextrasystolic T wave changes are common and lack predictive value. Postextrasystolic U wave changes may be a specific marker of a tendency to the development of spontaneous ventricular arrhythmias. Prospective studies should be performed to confirm this association.

The long QT syndrome. Prospective longitudinal study of 328 families.

The Long QT Syndrome (LQTS) is an infrequently occurring familial disorder in which affected individuals have electrocardiographic QT interval prolongation and a propensity to ventricular tachyarrhythmic syncope and sudden death. We prospectively investigated the clinical characteristics and the long-term course of 3,343 individuals from 328 families in which one or more members were identified as affected with LQTS (QTc greater than 0.44 sec1/2). The first member of a family to be identified with LQTS, the proband, was usually brought to medical attention because of a syncopal episode during childhood or teenage years. Probands (n = 328) were younger at first contact (age 21 +/- 15 years), more likely to be female (69%), and had a higher frequency of preenrollment syncope or cardiac arrest with resuscitation (80%), congenital deafness (7%), a resting heart rate less than 60 beats/min (31%), QTc greater than or equal to 0.50 sec1/2 (52%), and a history of ventricular tachyarrhythmia (47%) than other affected (n = 688) and unaffected (n = 1,004) family members. Arrhythmogenic syncope often occurred in association with acute physical, emotional, or auditory arousal. The syncopal episodes were frequently misinterpreted as a seizure disorder. By age 12 years, 50% of the probands had experienced at least one syncopal episode or death. The rates of postenrollment syncope (one or more episodes) and probable LQTS-related death (before age 50 years) for probands (n = 235; average follow-up 54 months per patient) were 5.0% per year and 0.9% per year, respectively; these event rates were considerably higher than those observed among affected and unaffected family members. Among 232 probands and 1,264 family members with prospective follow-up, three factors made significant independent contributions to the risk of subsequent syncope or probable LQTS-related death before age 50 years, whichever occurred first (Cox hazard ratio; 95% confidence limits): 1) QTc (1.052; 1.017, 1.088), 2) history of cardiac event (3.1; 1.3, 7.2), and 3) heart rate (1.017; 1.004, 1.031). The findings from this prospective longitudinal study highlight the clinical features, risk factors, and course of LQTS.

Beta-blocker therapy in patients ventricular tachyarrhythmias in the setting of left ventricular dysfunction

Although several studies suggest beta blockers (BB) are effective in suppressing ventricular arrhythmias, less is known about their role in the treatment of patients with ventricular tachyarrhythmias associated with impaired left ventricular function. To assess the tolerance and efficacy of these agents, 32 patients presenting with either ventricular fibrillation (18) or sustained ventricular tachycardia (14) were studied during BB therapy. Left ventricular dysfunction (mean ejection fraction 29%) was present as a consequence of coronary artery disease (26) or cardiomyopathy (6). Baseline arrhythmia assessment revealed recurrent ventricular tachycardia in all patients. Antiarrhythmic drug therapy including BB was guided by programmed stimulation (10), exercise testing (8), ambulatory monitoring (12), or was given empirically (2). Beta blockers were well tolerated, as measured by exercise duration, which improved significantly, and by long-term maintenance, which continued in 23 of 32 (72%) patients. Over a mean follow-up of 668 days, patients treated with BB had a relatively low incidence of both sudden (3%) and nonsudden (9%) death. Thus, BB can be effective and well tolerated adjunct therapy in patients with a history of ventricular tachyarrhythmias in the setting of impaired left ventricular function.

Surgical ablation of ventricular tachycardia with sequential map-guided subendocardial resection: electrophysiologic assessment and long-term follow-up.

A new operative technique of sequential map-guided subendocardial resection (SER) was used in 45 consecutive patients for the treatment of sustained ventricular tachycardia due to coronary artery disease. This technique is characterized by map-guided SER or cryothermic ablation during normothermic cardiopulmonary bypass, followed by repeated sequences of programmed stimulation to assess adequacy of resection. The patients' mean age was 59 +/- 10 years and the mean left ventricular ejection fraction was 34 +/- 12%. Twenty-five (56%) patients had a history of myocardial infarction within the previous 2 months. After ventriculotomy, 34 patients (76%) had inducible monomorphic ventricular tachycardia. These patients underwent repeated sequences of ventricular tachycardia induction and mapping during normothermic bypass followed by successive SER or cryothermic ablation until sustained monomorphic ventricular tachycardia was no longer inducible. Twenty-seven patients had a total of 60 discrete, mappable tachycardias induced and seven patients had 10 discrete tachycardias that were too fast to accurately map. In the remaining 11 patients, no ventricular tachycardia was inducible after ventriculotomy and SER, which included all visually identifiable scar, was performed. The mean cardiopulmonary bypass time was 102 +/- 27 min. Forty-one of 45 patients (91%) survived to hospital discharge, and 35 of 41 patients (85%) had no inducible ventricular tachycardia at postoperative electrophysiologic evaluation performed in the absence of all antiarrhythmic drugs. The remaining six patients had no inducible ventricular tachycardia with drug therapy. All four operative nonsurvivors had refractory cardiac collapse preoperatively. Over 19 +/- 12 months of follow-up, there were four sudden cardiac deaths and no nonfatal recurrences of ventricular tachycardia. There were seven additional cardiac deaths. Actuarial cardiac survival was 0.57, and freedom from arrhythmic events was 0.76 at 42 months. Thus, in the absence of cardiogenic shock, the technique of sequential map-guided SER achieves: (1) a high operative survival with acceptable perfusion times, (2) excellent long-term arrhythmia control, and (3) survival comparable to that in patients with similar left ventricular function and no history of ventricular tachyarrhythmia.