Thomas Wolber

Appropriate Therapy But Not Inappropriate Shocks Predict Survival in Implantable Cardioverter Defibrillator Patients

Inappropriate implantable cardioverter defibrillator (ICD) shocks have been linked to a worse clinical outcome due to direct myocardial injury.

Electrophysiological findings in patients with isolated left ventricular non-compaction.

AIMS Patients with isolated left ventricular non-compaction (IVNC) are at high risk for developing ventricular tachyarrhythmias. However, no analysis of invasive electrophysiological (EP) findings in these patients has yet been performed. METHODS AND RESULTS We performed a retrospective analysis of EP findings in 24 patients with IVNC. Ventricular tachyarrhythmias were inducible in nine patients; of these, two patients had sustained monomorphic ventricular tachycardia (VT) and two patients had ventricular fibrillation. No specific electrocardiographic or echocardiographic finding was predictive of VT inducibility. Three of the 9 patients with inducible VT experienced ventricular tachyarrhythmias during the follow-up of 61.4+/-50 months, whereas no tachyarrhythmias or sudden deaths were noted in 12 patients without inducible VT during the follow-up of 30+/-19 months (3 patients in the latter group were lost to follow-up). Supraventricular tachyarrhythmias were inducible in seven patients. CONCLUSION Our present study provides the first comprehensive analysis of EP findings in patients with IVNC. Ventricular and supraventricular arrhythmias can readily be induced in these patients, whereas the inducibility of a sustained monomorphic VT is relatively low. Further studies including long-term follow-up are required to investigate the role of EP testing for arrhythmic risk stratification in these patients.

Predictors of Appropriate ICD Therapy in Patients with Arrhythmogenic Right Ventricular Cardiomyopathy: Long Term Experience of a Tertiary Care Center

Introduction Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a rare genetically transmitted disease prone to ventricular arrhythmias. We therefore investigated the clinical, echocardiographical and electrophysiological predictors of appropriate implantable cardioverter defibrillator (ICD) therapy in patients with ARVC. Methods A retrospective analysis was performed in 26 patients (median age of 40 years at diagnosis, 21 males and 5 females) with ARVC who underwent ICD implantation. Results Over a median (range) follow-up period of 10 (2.7, 37) years, appropriate ICD therapy for ventricular arrhythmias was documented in 12 (46%) out of 26 patients. In all patients with appropriate ICD therapy the ICD was originally inserted for secondary prevention. Median time from ICD implantation to ICD therapy was 9 months (range 3.6, 54 months). History of heart failure was a significant predictor of appropriate ICD therapy (p = 0.033). Left ventricular disease involvement (p = 0.059) and age at implantation (p = 0.063) were borderline significant predictors. Patients with syncope at time of diagnosis were significantly less likely to receive ICD therapy (p = 0.02). Invasive electrophysiological testing was not significantly associated with appropriate ICD therapy. Conclusion In our cohort of patients with ARVC, history of heart failure was a significant predictor of appropriate ICD therapy, whereas left ventricular involvement and age at time of ICD implantation were of borderline significance. These predictors should be tested in larger prospective cohorts to optimize ICD therapy in this rare cardiomyopathy.

Comparison of Benefit and Mortality of Implantable Cardioverter–Defibrillator Therapy in Patients Aged ≥75 Years Versus Those <75 Years

Implantable cardioverter-defibrillator (ICD) therapy decreases arrhythmic and all-cause mortality in patients at high risk of sudden death. However, its clinical benefit in elderly patients is uncertain. The aim of this study was to assess the long-term efficacy of ICD treatment in elderly patients and to identify markers of successful ICD therapy and risk factors of mortality. We performed multivariate analysis of a prospective long-term database from 2 tertiary care centers including 936 consecutive patients with an ICD. Predictors of ICD therapy and risk factors for mortality were assessed in patients ≥75 years old at ICD implantation compared to younger patients. Mean follow-up time was 43 ± 40 months. Rates of ICD therapy were similar in the 2 age groups. No significant predictors of ICD therapy could be identified in older patients. Median estimated survival was 132 months in patients <75 years and 81 months in those ≥75 years old (p = 0.006). Decreased ejection fraction (hazard ratio 1.62 per 10% decrease, p = 0.03) and impaired renal function (hazard ratio 1.57 per 10 ml/kg/m(2) decrease in estimated glomerular filtration rate, p = 0.02) were independent risk factors of mortality in patients ≥75 years old. However, mortality of older patients was similar to that of the age-matched general population irrespective of delivery of ICD therapy. In conclusion, ICD therapy is effective for treatment of life-threatening arrhythmias in all age groups. However, prevention of sudden cardiac death may have limited impact on overall mortality in older patients. Despite a similar rate of appropriate ICD therapies, risk of death is increased 1.6-fold in ICD recipients ≥75 years old compared to younger patients. Patients with decreased ejection fraction and impaired renal function are at highest risk.

N-terminal pro-brain natriuretic peptide used for the prediction of coronary artery stenosis

Background  The level of the inactive N‐terminal fragment of pro‐brain (B‐type) natriuretic peptide (NT‐proBNP) is a prognostic marker in patients with acute and chronic coronary artery disease (CAD). It might also be valuable for non‐invasive diagnosis of coronary artery disease.

A nomogram to select the optimal treadmill ramp protocol in subjects with high exercise capacity: validation and comparison with the Bruce protocol.

PURPOSE Guidelines suggest that individualized ramp protocols with treadmill times targeted between 8 and 12 minutes are most suitable to estimate exercise capacity. However, previous methods to determine individualized ramp rates and comparisons between ramp and standardized protocols have been limited to clinically referred populations. METHODS Forty-three healthy volunteers [median (interquartile range), age 36 (30-41) years; 10 women] performed an individualized ramp and a Bruce treadmill exercise protocol in random order. The Veterans Specific Activity Questionnaire [VSAQ, resulting in metabolic equivalents (METs)VSAQ] combined with a modified variant of the VSAQ nomogram (resulting in METs(NOMOGRAM)) was used to individualize the ramp protocol. Exercise capacity estimated from speed and grade of the treadmill (METs(ESTIMATED)) and that derived from directly measured peak oxygen uptake (VO2) [METs(MEASURED)] were compared with the pretest estimates of exercise capacity. RESULTS Median values for METs(VSAQ), METs(NOMOGRAM), METs(ESTIMATED), and METs(MEASURED) for the ramp protocol were 12.0 (10-12), 15.0 (14-16.5), 16.7 (15.9-17.8), and 15.2 (13.5-16.7), respectively. For the ramp protocol, all 43 participants achieved a treadmill time between 8 and 12 minutes, whereas with the Bruce protocol only 6 (14%) participants fell within this range (P < .0001). Peak VO2 [ramp: 53.1 (47.4-58.3) versus Bruce: 53.5 (48.7-58.3) mL/kg/min; P = .008] was slightly lower using the ramp protocol. CONCLUSIONS The modified variant of the VSAQ nomogram is a useful tool to estimate an individuals exercise capacity and to select a treadmill ramp protocol to yield the recommended exercise duration for moderately to highly fit, healthy individuals. The individualized ramp and the Bruce protocols are similar with regard to directly measured peak VO2 achieved.

Usefulness of Electrocardiographic Parameters for Risk Prediction in Arrhythmogenic Right Ventricular Dysplasia

The value of electrocardiographic findings predicting adverse outcome in patients with arrhythmogenic right ventricular dysplasia (ARVD) is not well known. We hypothesized that ventricular depolarization and repolarization abnormalities on the 12-lead surface electrocardiogram (ECG) predict adverse outcome in patients with ARVD. ECGs of 111 patients screened for the 2010 ARVD Task Force Criteria from 3 Swiss tertiary care centers were digitized and analyzed with a digital caliper by 2 independent observers blinded to the outcome. ECGs were compared in 2 patient groups: (1) patients with major adverse cardiovascular events (MACE: a composite of cardiac death, heart transplantation, survived sudden cardiac death, ventricular fibrillation, sustained ventricular tachycardia, or arrhythmic syncope) and (2) all remaining patients. A total of 51 patients (46%) experienced MACE during a follow-up period with median of 4.6 years (interquartile range 1.8 to 10.0). Kaplan-Meier analysis revealed reduced times to MACE for patients with repolarization abnormalities according to Task Force Criteria (p = 0.009), a precordial QRS amplitude ratio (∑QRS mV V1 to V3/∑QRS mV V1 to V6) of ≤ 0.48 (p = 0.019), and QRS fragmentation (p = 0.045). In multivariable Cox regression, a precordial QRS amplitude ratio of ≤ 0.48 (hazard ratio [HR] 2.92, 95% confidence interval [CI] 1.39 to 6.15, p = 0.005), inferior leads T-wave inversions (HR 2.44, 95% CI 1.15 to 5.18, p = 0.020), and QRS fragmentation (HR 2.65, 95% CI 1.1 to 6.34, p = 0.029) remained as independent predictors of MACE. In conclusion, in this multicenter, observational, long-term study, electrocardiographic findings were useful for risk stratification in patients with ARVD, with repolarization criteria, inferior leads TWI, a precordial QRS amplitude ratio of ≤ 0.48, and QRS fragmentation constituting valuable variables to predict adverse outcome.

Long-term predictors of mortality in ICD patients with non-ischaemic cardiac disease: impact of renal function

BACKGROUND Randomized trials have demonstrated that implantable cardioverter defibrillator (ICD) therapy may reduce the risk of death in patients with non-ischaemic cardiomyopathy (CMP). In this study, we aimed at determining the long-term benefit of ICD therapy among patients with dilated CMP (DCM) and among those with other non-ischaemic cardiac diseases (NICDs). METHODS AND RESULTS We performed a single-centre longitudinal study to assess the outcomes of 176 patients with NICDs who were implanted with an ICD for primary or secondary prevention of cardiac death. The cumulative survival rate after 1, 2, 5, and 10 years was 91, 87, 78, and 65%, respectively. Mortality risk did not differ significantly between patients with DCM and those with other NICDs. Atrial fibrillation, recurrent ventricular arrhythmias requiring ICD therapy, and right ventricular pacing, but not delayed intrinsic ventricular conduction, were associated with higher risk. New York Heart Association (NYHA) functional class > or =III was an independent predictor of adverse outcome among patients with DCM [hazard ratio (HR) 5.27, P = 0.01], whereas reduced left ventricular function with ejection fraction <35% (HR 12.1, P < 0.001) and anti-arrhythmic drug use (HR 4.82, P = 0.03) were independent predictors among those with other NICDs. Renal insufficiency with estimated glomerular filtration rate <60 mL/min/1.73 m(2) (HR 5.9, P < 0.001) was a strong independent predictor of mortality among all patients with NICD, irrespective of underlying cardiac condition. CONCLUSION In ICD patients with DCM, higher NYHA functional class is associated with adverse outcomes. Impaired left ventricular function and anti-arrhythmic drug use predict higher mortality among patients with non-dilated, NICDs. Impaired renal function is a strong predictor of mortality in all patients with NICD.

Cardiopulmonary Exercise Testing in Mild Heart Failure: Impact of the Mode of Exercise on Established Prognostic Predictors

Objectives: In patients with heart failure (HF), peak oxygen consumption (peak VO2), the relationship between minute ventilation and carbon dioxide production (VE/VCO2 slope) and heart rate recovery (HRR) are established prognostic predictors. However, treadmill exercise has been shown to elicit higher peak VO2 values than bicycle exercise. We sought to assess whether the VE/VCO2 slope and HRR in HF also depend on the exercise mode. Methods: Twenty-one patients with mild HF on chronic β-blocker therapy underwent treadmill and bicycle cardiopulmonary exercise testing for measurement of peak VO2 and the VE/VCO2 slope. In patients with sinus rhythm (n = 16), HRR at 1 (HRR-1) and 2 min (HRR-2) after exercise termination was assessed. Results: Peak VO2 was higher during treadmill as compared with bicycle testing (21.7 ± 4.6 vs. 19.6 ± 3.4 ml/kg/min; p = 0.006). HRR-1 tended to be slower (15 bpm, interquartile range 8–19, vs. 18 bpm, interquartile range 11–22; p = 0.16), and HRR-2 was significantly slower after treadmill exercise (26 bpm, interquartile range 20–39, vs. 31 bpm, interquartile range 22–41; p = 0.04). In contrast, VE/VCO2 slope values did not differ between the test modes (32.9 ± 5.5 vs. 32.3 ± 5.0; p = 0.56). Conclusions: In contrast to peak VO2 and HRR, the VE/VCO2 slope is not affected by the exercise mode in patients with mild HF.

Wavelet-based tachycardia discrimination in ICDs: Impact of posture and electrogram configuration.

Background: Inappropriate therapy delivery is an important concern in the management of patients with implantable cardioverter defibrillators (ICDs). Recently, a morphology‐based algorithm (wavelet feature) has been introduced for differentiation of ventricular and supraventricular tachycardia. In this study, we evaluated the performance of the wavelet algorithm using various electrogram (EGM) configurations during different body positions.