Incidence and Predictors of Out-of-Hospital Cardiac Arrest Within 90 Days After Myocardial Infarction.

BACKGROUND: The risk of sudden cardiac death (SCD) is high early after myocardial infarction (MI). Current knowledge and guidelines mainly rely on results from older clinical trials and registry studies. Left ventricular ejection fraction (LVEF) alone has not been proven a reliable predictor of SCD. OBJECTIVES: This study sought to identify the incidence and additional predictors of SCD early after MI in a contemporary nationwide setting. METHODS: The authors used data from SWEDEHEART, the Swedish Cardiopulmonary Resuscitation Registry, and the Swedish Pacemaker and Implantable Cardioverter-Defibrillator (ICD) Registry. Cases of MI, which had undergone coronary angiography and were discharged alive between 2009 to 2017 without a prior ICD, were followed up to 90 days. Cox regression models were used to assess associations between clinical parameters and out-of-hospital cardiac arrest (OHCA). RESULTS: Among 121,379 cases, OHCA occurred in 349 (0.29%) and non-OHCA death in 2,194 (1.8%). A total of 6 variables (male sex, diabetes, estimated glomerular filtration rate <30 ml/min/1.73 m2, Killip class ≥II, new-onset atrial fibrillation/flutter, and impaired LVEF [reference ≥50%] categorized as 40% to 49%, 30% to 39%, and <30%) were identified as independent predictors, were assigned points, and were grouped into 3 categories, where the incidence of OHCA ranged from 0.12% to 2.0% and non-OHCA death from 0.76% to 11.7%. Stratified by LVEF <40% alone, the incidence of OHCA was 0.20% and 0.76% and for non-OHCA death 1.1% and 4.9%. CONCLUSIONS: In this nationwide study, the incidence of OHCA within 90 days after MI was <0.3%. A total of 5 clinical parameters in addition to LVEF predicted OHCA and non-OHCA death better than LVEF alone.

Causes of death and mortality in hypertrophic cardiomyopathy patients with implantable defibrillators in Sweden.

AIMS: Implantable defibrillators (ICDs) successfully terminate ventricular arrhythmias in hypertrophic cardiomyopathy (HCM), protect against bradycardia, and monitor atrial arrhythmias. This may alter the natural history and causes of death. METHODS: This nationwide observational longitudinal retrospective study of all HCM patients implanted during 1995-2012 obtained data from the Swedish ICD Registry, the National Patient Register, the Cause of Death Register, and were validated by review of medical records. RESULTS: Of 342 patients (mean age 51.8 years, 70.8% males), 45 died during a total follow-up of 1847 years (mean 5.4 years). Mean age at death was 68.2 years (range 21-83 years; 12 were ≥75 years). Mean follow-up time among the deceased was 4.9 years (quartiles 1.4-7.4 years). All-cause mortality was higher in HCM patients compared with the age and sex-matched Swedish general population (standardized mortality ratio 3.4; 95% confidence interval 2.4-4.5; P < 0.001). Main cause of death was heart failure (n = 27), stroke (n = 5), cancer (n = 3), myocardial infarction (n = 2), sepsis (n = 2), and others (n = 4). Two patients died suddenly, one after the ICD was turned off because of inappropriate shocks, and one patient whose device system was removed after infection. HCM was the main cause of death in 76% of the cases, mainly because of progressive heart failure. CONCLUSION: For HCM patients, ICDs almost eliminate premature arrhythmic death and result in a shift to heart failure as the cause of death in the majority of cases. Still, mortality in HCM patients remains elevated and management of heart failure and comorbidities must be improved to increase survival.

Hypertrophic Cardiomyopathy and Implantable Defibrillators in Sweden: Inappropriate Shocks and Complications Requiring Surgery.

INTRODUCTION: The expanded use of implantable cardioverter-defibrillators (ICDs) to prevent sudden cardiac death (SCD) in hypertrophic cardiomyopathy (HCM) based on risk stratification in individuals without known previous ventricular arrhythmia is justified by an acceptable risk of device-related adverse events. Such complications, leading to surgical procedures or inappropriate electrical shocks, may impact mortality, morbidity, quality of life, and cost-effectiveness. METHODS AND RESULTS: From the Swedish ICD Registry, implants due to HCM since 1995 until November 2012 in patients aged ≥18 years were identified and medical records reviewed. Inappropriate ICD shock occurred in 14.3% (46 of 321 patients; mean follow-up 5.4 years) with a recurrent episode in 28.2% of them. In multivariable analysis, hazard ratio (HR) for atrial fibrillation was 3.5 (95% confidence interval 1.8-6.8; P < 0.001) but showed no significant association to male sex (HR = 0.77), age (HR = 0.99), secondary indication (HR = 1.02) or device, ICD-DR/CRTD vs. ICD-VR (HR 1.07). Inappropriate shocks were triggered by atrial fibrillation/flutter or ectopic tachycardia (56.5%), sinus tachycardia (14.5%), lead dysfunction (14.5%), and T-wave oversensing (13.0%). A reintervention, besides elective device replacement, occurred in 92 patients (totally 150 procedures). The majority were lead-related (70.0%) procedures, especially of the ICD lead. Reintervention was associated with female sex (HR = 1.6 P = 0.04). CONCLUSION: Inappropriate ICD shock triggered by atrial arrhythmias, lead dysfunction, or complications requiring surgical interventions, is a concern in HCM patients who will be eligible for long-term prevention of sudden death. Efforts to avoid adverse events and provide balanced risk-benefit information are important, especially in primary prevention.