QRS fragmentation does not predict mortality in survivors of acute myocardial infarction

BACKGROUND

Despite advances in coronary revascularization and in heart failure management, myocardial infarction survivors remain at substantially increased mortality risk. Precise risk assessment and risk-adapted follow-up care are crucial to improve their outcomes. Recently, the fragmented QRS complex, i.e. the presence of additional spikes within the QRS complexes on a 12-lead electrocardiogram, has been discussed as a potential non-invasive risk predictor in cardiac patients.

HYPOTHESIS

The aim of this study was to evaluate the prognostic meaning of the fragmented QRS complex in myocardial infarction survivors.

METHODS

609 patients with narrow QRS complexes <120 ms were included in a prospective cohort study while hospitalized for myocardial infarction and followed for 5 years.

RESULTS

The prevalence of the fragmented QRS complex in these patients amounted to 46.8% (285 patients). These patients had no increased hazard of all-cause death (HR 0.84, 95%-CI 0.45-1.57, p = 0.582) with a mortality rate of 6.0% compared to 7.1% in patients without QRS fragmentations. Furthermore, the risks of cardiac death (HR 1.28, 95%-CI 0.49-3.31, p = 0.613) and of non-cardiac death (HR 0.6, 95%-CI 0.26-1.43, p = 0.25) were not significantly different in patients with QRS fragmentations. However, patients with QRS fragmentations had increased serum creatine kinase concentrations (1438U/l vs. 1160U/l, p = 0.039) and reduced left ventricular ejection fractions (52% vs. 54%, p = 0.011).

CONCLUSIONS

The hypothesis that QRS fragmentation might be a prognostic parameter in survivors of myocardial infarction was not confirmed. But those with QRS fragmentation had larger myocardial infarctions, as measured by creatine kinase and left ventricular ejection fraction.

The MADIT-ICD benefit score helps to select implantable cardioverter-defibrillator candidates in cardiac resynchronization therapy

AIMS

The aim of this study is to evaluate whether the MADIT-ICD benefit score can predict who benefits most from the addition of implantable cardioverter-defibrillator (ICD) to cardiac resynchronization therapy (CRT) in real-world patients with heart failure with reduced ejection fraction (HFrEF) and to compare this with selection according to a multidisciplinary expert centre approach.

METHODS AND RESULTS

Consecutive HFrEF patients who received a CRT for a guideline indication at a tertiary care hospital (Ziekenhuis Oost-Limburg, Genk, Belgium) between October 2008 and September 2016, were retrospectively evaluated. The MADIT-ICD benefit groups (low, intermediate, and high) were compared with the current multidisciplinary expert centre approach. Endpoints were (i) sustained ventricular tachycardia (VT) or ventricular fibrillation (VF) and (ii) non-arrhythmic mortality. Of the 475 included patients, 165 (34.7%) were in the lowest, 220 (46.3%) in the intermediate, and 90 (19.0%) in the highest benefit group. After a median follow-up of 34 months, VT/VF occurred in 3 (1.8%) patients in the lowest, 9 (4.1%) in the intermediate, and 13 (14.4%) in the highest benefit group (P < 0.001). Vice versa, non-arrhythmic death occurred in 32 (19.4%) in the lowest, 32 (14.6%) in the intermediate, and 3 (3.3%) in the highest benefit group (P = 0.002). The predictive power for ICD benefit was comparable between expert multidisciplinary judgement and the MADIT-ICD benefit score: Uno's C-statistic 0.69 vs. 0.69 (P = 0.936) for VT/VF and 0.62 vs. 0.60 (P = 0.790) for non-arrhythmic mortality.

CONCLUSION

The MADIT-ICD benefit score can identify who benefits most from CRT-D and is comparable with multidisciplinary judgement in a CRT expert centre.

Heart failure treatment in patients with cardiac implantable electronic devices: Opportunity for improvement

BACKGROUND

Heart failure and reduced ejection fraction (HFrEF) is the predominant indication for cardiac resynchronization therapy (CRT) and implantable cardioverter-defibrillator (ICD) implantation. The care gap and opportunity to optimize guideline-directed medical therapy (GDMT) is unclear.

OBJECTIVE

We sought to define uptake, eligibility, dose, and adherence to GDMT in patients with CRT/ICD and HFrEF.

METHODS

MEDLINE was searched from 2000 to July 2021 for major randomized trials, registries, and cohort studies evaluating GDMT in this population. Thirty-eight studies focused on medical therapy in patients with CRT/ICD devices (CRT = 23, ICD = 11, and both = 4).

RESULTS

In the pivotal device trials, ACEI/ARB and beta-blocker use was high (mean 94%, range 41%-99%; and 83%, range 27%-97%, respectively), but mineralocorticoid receptor antagonists were modest (mean 45%, range 32%-61%), in keeping with guidelines of that era. Similar results were found in observational registries. CRT was associated with beta-blocker uptitration, while the effects on ACEI/ARB were less consistent. For beta blockers, 57%-68% of patients were uptitrated, increasing the mean percent of target dose achieved by 24% from baseline to follow-up. In one study, adherence increased, for ACEI/ARB from 37% to 55% and beta blockers 34% to 58%. Only 1 study assessed potential eligibility at implant for sacubitril-valsartan (72%) or ivabradine (28%), and no study examined sodium-glucose cotransporter-2 inhibitors. Increased uptake, titration, and dose was associated with reduced mortality, hospitalization, and device therapies.

CONCLUSION

Patients with HFrEF and ICD/CRT are undertreated with respect to GDMT, and there is opportunity to optimize therapy to improve morbidity and mortality.

Deactivation of implantable defibrillators at end of life - Can we do better?

INTRODUCTION

Dying patients with implantable defibrillators (ICD) have a risk of receiving unnecessary shocks before death. The aim of this study was to investigate if deactivation of shock therapy at end-of-life has increased since publication of new guidelines in 2010 on ICD management.

METHOD AND RESULTS

This is a study of two groups of ICD patients who died in hospitals before and after publication of new guidelines. Group 1 consists of 89 patients who died between 2003 and 2010. Group 2 consists of 252 patients, the total number of ICD patients in Sweden who died in hospital during 2014. Data was obtained from the Swedish ICD and Pacemaker Registry, Swedish Tax Agency and patient medical notes. Two-thirds died in wards other than Cardiology. Fifty-four percent in group 1 had a Do-Not-Resuscitate-order (DNR) compared to 73% in group 2. Shock deactivation was present in 52% in group 1 and 67% in group 2. The difference in shock deactivation between group 1 and 2 was only significant (p = 0.014) for DNR-patients treated in Cardiology. A significant difference (p = 0.036) was found in deactivation within group 2 between DNR-patients in Cardiology vs. DNR-patients in Non-Cardiology wards.

CONCLUSION

Two-thirds of ICD patients die in wards other than Cardiology. Since publication of guidelines on ICD management there is a general increase in shock deactivation for DNR-patients, but only significant for patients in Cardiology. This implicate that actions have to be taken for patients treated in Non-Cardiology wards to bridge the gap between guidelines recommendations and clinical practice.

Baroreflex sensitivity assessed with the sequence method is associated with ventricular arrhythmias in patients implanted with a defibrillator for the primary prevention of sudden cardiac death

BACKGROUND

Left ventricular ejection fraction lacks accuracy in predicting sudden cardiac death, resulting in unnecessary implantation of cardioverter defibrillators for the primary prevention of sudden cardiac death. Baroreflex sensitivity could help to stratify patients at risk of ventricular arrhythmia.

AIM

To assess the association between cardiac baroreflex sensitivity and ventricular arrhythmias in patients implanted with an implantable cardioverter defibrillator for the primary prevention of sudden cardiac death after myocardial infarction.

METHODS

This case-control single-centre study took place between 2015 and 2016. Cases (n=10) had experienced ventricular arrhythmias treated by the implantable cardioverter defibrillator in the previous 3 years; controls (n=22) had no arrhythmia during the same period. Baroreflex sensitivity was assessed using the temporal sequence method (mean slope) and cross-spectral analysis (low-frequency gain and high-frequency gain).

RESULTS

The mean age was 65 years; 94% of the patients were men. 24-hour Holter electrocardiogram autonomous nervous system variables, left ventricular ejection fraction and N-terminal prohormone of B-type natriuretic peptide (NT-proBNP) concentration did not differ between cases and controls. The mean slope was lower in cases than in controls (8 vs. 15ms/mmHg [P=0.009] in the supine position; 7 vs. 12ms/mmHg [P=0.038] in the standing position). The mean slope in the supine position was still significantly different between groups after adjustment for age, left ventricular ejection fraction and NT-proBNP (P=0.03). By comparison, low-frequency gain and high-frequency gain did not differ between groups in either the supine or the standing position.

CONCLUSION

Patients with ventricular arrhythmias had a lower mean slope compared with those who were free of arrhythmia. A prospective study is needed to confirm this association.

Long-term complications, reoperations and survival following cardioverter-defibrillator implant

OBJECTIVE

Implantable cardioverter-defibrillators (ICDs) reduce risk of death in select populations, but are also associated with harms. We aimed to characterise long-term complications and reoperation rate.

METHODS

We assessed the rate, cumulative incidence and predictors of long-term reoperation and survival using a prospective, multicentre registry serving British Columbia in Canada, a universal single payer healthcare system with 4.5 million residents. 3410 patients (mean 63.3 years, 81.7% male) with new primary (n=1854) or secondary prevention (n=1556) ICD implant from 2003 to 2012 were followed for a median of 34 months (single chamber n=1069, dual chamber n=1905, biventricular n=436). Independent predictors of adverse outcomes were defined using Cox regression models.

RESULTS

The overall reoperation rate was 12.0% per patient-year, and less for single vs dual vs biventricular ICDs (9.1% vs 12.5% vs 17.8% per patient-year, respectively). The Kaplan-Meier complication estimates (excluding generator end of life) at 1, 3 and 5 years were respectively: single chamber 10.2%, 16.2% and 21.6%; dual 11.7%, 19.1% and 27.4% and biventricular 15.9%, 22.2% and 24.7%. Cardiac resynchronisation therapy had the highest rate of early lead complications, but lower long-term need for upgrade. Device complexity, age and atrial fibrillation were key determinants of complications. Overall mortality at 1, 3 and 5 years was 5.4%, 17.4% and 32.7%, respectively. In younger patients, observed 5-year survival approached the expected survival in the general population (relative survival ratio=0.96 (0.90-0.98)). With increasing age, observed survival steadily declined relative to expected.

CONCLUSIONS

In a prospective registry capturing all procedures, complication and reoperation rates following de novo ICD implantation were high. Shared decision making must carefully consider these factors.

Clinical risk profile score predicts all cause mortality but not implantable cardioverter defibrillator intervention rate in a large unselected cohort of patients with congestive heart failure

BACKGROUND

Primary prophylactic implantable cardioverter defibrillator (ICD) therapy is indicated for patients with reduced left ventricular ejection fraction (LVEF). We aimed to determine if preoperative clinical risk profiling can predict long-term benefit, and if clinical risk scores can be applied and improved in a patient cohort outside the clinical trial setting.

METHODS

Using registry data, 789 patients with reduced LVEF who received ICDs for primary prevention during 2006-2011 were identified (age 64 ± 11 years, 82% men, 63% ischemic etiology, 52% cardiac resynchronization therapy with defibrillator). The patients were divided into three risk groups, based on the presence of baseline clinical risk factors (age >70, QRS duration >120 ms, New York Heart Association class III-IV, atrial fibrillation history, or creatinine >106 μmol/L). Endpoints were all-cause mortality and survival free of adequate ICD therapy.

RESULTS

Mean follow-up was 39 ± 18 months. Annual mortality was 7.6%, and increased with risk group (p < .001). Rates of appropriate antitachycardia pacing and shock therapy were not statistically different between the groups, and ranged from 11%-16% and 6%-14%, respectively. By combining the previous risk score with data on diabetes, a better independent prediction of mortality was achieved; mortality rates then ranged from 11% (low-risk) to 46% (high-risk) (p < .0001).

CONCLUSIONS

Implantable cardioverter defibrillator therapies occur across the spectrum of comorbidities in a population with systolic heart failure. However, all-cause mortality is considerably higher in the group of patients with accumulated risk factors, and using the proposed scoring system can be helpful for the evaluation and risk stratification of the patient prior to making a decision for a primary prophylactic ICD implantation.

Long-Term Prognosis of Patients with an Implantable Cardioverter-Defibrillator in Korea

PURPOSE

The objective of this study was to elucidate the long-term prognosis of patients with implantable cardioverter-defibrillators (ICDs) in Korea.

MATERIALS AND METHODS

We enrolled 405 patients (age, 57.7±16.7 years; 311 men) who had undergone ICD implantation. The patients were divided into three groups: heart failure (HF) and ICD for primary (group 1, n=118) and secondary prevention (group 2, n=93) and non-HF (group 3, n=194). We compared appropriate and inappropriate ICD therapy delivery among the groups and between high- (heart rate ≥200 /min) and low-rate (<200 /min) ICD therapy zones.

RESULTS

During the follow-up period (58.9±49.8 months), the annual appropriate ICD therapy rate was higher in group 2 (10.4%) than in groups 1 and 3 (6.1% and 5.9%, respectively, p<0.001). There were no significant differences in annual inappropriate ICD therapy rate among the three groups. In group 1, the annual appropriate ICD therapy rate was significantly lower in patients with a high-rate versus a low-rate therapy zone (4.5% and 9.6%, respectively, p=0.026). In group 3, the annual inappropriate ICD therapy rate was significantly lower in patients with a high-rate versus a low-rate therapy zone (3.1% and 4.0%, respectively, p=0.048).

CONCLUSION

Appropriate ICD therapy rates are not low in Korean patients with ICD, relative to prior large-scale studies in Western countries. Appropriate and inappropriate ICD therapy could be reduced by a high-rate therapy zone in patients with HF and ICD for primary prevention, as well as non-HF patients, respectively.