Daily Cardiology Research Analysis

BACKGROUND: The most common causes of death may change over time in heart failure with reduced ejection fraction (HFrEF). These shifts can influence the risk-benefit balance of interventions such as implantable cardioverter-defibrillators (ICDs), which are designed to prevent sudden cardiac death. Long-term follow-up is therefore essential to determine whether early benefits are sustained, attenuated, or lost over time. OBJECTIVES: This study sought to examine the long-term effect of primary prevention ICD implantation, compared with usual clinical care, in patients with nonischemic HFrEF enrolled in the DANISH (Danish Study To Assess the Efficacy of ICDs in Patients With Nonischemic Systolic Heart Failure on Mortality) trial. METHODS: The DANISH trial enrolled 1,116 patients with nonischemic HFrEF, left ventricular ejection fraction ≤35%, NYHA functional class II-III (class IV if cardiac resynchronization therapy was planned), and elevated natriuretic peptide levels. The primary outcome was all-cause death, and secondary outcomes were cardiovascular death and sudden cardiovascular death. In this study with extended follow-up, patients were followed until death or January 31, 2024, whichever came first. RESULTS: During a median follow-up of 13.2 years (Q1-Q3: 11.6-14.6 years), 294 patients (52.9%) in the ICD group and 299 (53.4%) in the control group died. Compared with usual clinical care, ICD implantation did not significantly reduce the long-term rate of all-cause death (HR: 0.96; 95% CI: 0.82-1.13), but it did reduce the long-term rate of sudden cardiovascular death (HR: 0.54; 95% CI: 0.36-0.80). The effect of ICD implantation on all-cause death was consistent regardless of age (P CONCLUSIONS: In patients with nonischemic HFrEF, during a median follow-up of 13.2 years, primary prevention ICD implantation did not reduce all-cause death, but it did reduce sudden cardiovascular death, and younger individuals appeared to derive a greater benefit. (Danish ICD Study in Patients With Dilated Cardiomyopathy [DANISH]; NCT00542945).

IMPORTANCE: Women with adverse pregnancy outcomes have higher subsequent cardiovascular risks, but their long-term risk of atrial fibrillation (AF) and potential causality are unclear. A better understanding of such risks is needed to identify women with high risk early in life and guide interventions to prevent AF and its complications. OBJECTIVE: To determine long-term risks of AF associated with 6 major adverse pregnancy outcomes in a large population-based cohort and assess for familial confounding using cosibling analyses. DESIGN, SETTING, AND PARTICIPANTS: This national cohort study included all women with a singleton delivery in Sweden between 1973 and 2015. Analyses were conducted between May 23 and August 18, 2025. EXPOSURES: Adverse pregnancy outcomes (preterm delivery, small for gestational age, large for gestational age, preeclampsia, other hypertensive disorders, and gestational diabetes), identified from nationwide birth records. MAIN OUTCOME AND MEASURES: The primary outcome was AF identified from nationwide inpatient and outpatient diagnoses through 2018. Cox regression was used to compute hazard ratios (HRs) for AF associated with specific adverse pregnancy outcomes, adjusting for other maternal factors. Cosibling analyses assessed for potential confounding by shared familial (genetic and/or environmental) factors. RESULTS: Among 2 201 047 women with 54 million person-years of follow-up, 51 173 (2.3%) were diagnosed with AF (median [IQR] age at diagnosis, 63 [56-69] years). All adverse pregnancy outcomes except small for gestational age were associated with long-term increased risks of AF. Within 10 years following delivery, adjusted HRs for AF were significantly elevated only among women with other hypertensive disorders (HR, 1.69; 95% CI, 1.32-2.15), preterm delivery (HR, 1.46; 95% CI, 1.26-1.70), or large for gestational age (HR, 1.16; 95% CI, 1.01-1.32). However, at 30 to 46 years after delivery, adjusted HRs were increased among women with other hypertensive disorders (HR, 1.44; 95% CI, 1.24-1.66), preeclampsia (HR, 1.38; 95% CI, 1.33-1.50), gestational diabetes (HR, 1.19; 95% CI, 1.03-1.37), large for gestational age (HR, 1.17; 95% CI, 1.14-1.21), or preterm delivery (HR, 1.11; 95% CI, 1.07-1.16). These findings were largely unexplained by shared familial factors. Women with multiple adverse pregnancy outcomes had further increases in risk. CONCLUSIONS: In this large national cohort, all adverse pregnancy outcomes except small for gestational age were associated with increased risk for AF up to 46 years later. Women with adverse pregnancy outcomes need early preventive actions and long-term clinical follow-up for timely detection and treatment of cardiovascular disorders related to the development of AF.

IMPORTANCE: Patients with heart failure may be particularly susceptible to nonoptimal temperature exposure, but the associations between short-term low and high temperature exposure and mortality in this population remain unclear, especially in Sweden-a high-latitude country where no nationwide study has been conducted. OBJECTIVE: To investigate the associations between short-term exposure to low and high ambient temperatures and all-cause and cardiovascular mortality among Swedish patients with heart failure. DESIGN, SETTING, AND PARTICIPANTS: This nationwide, time-stratified case-crossover study was conducted in Sweden among 250 640 patients with heart failure who died from any cause from 2006 to 2021, identified from the Swedish National Patient Register and the Cause of Death Register. EXPOSURE: Daily mean ambient temperature was assessed at 1 × 1-km spatial resolution. To account for regional adaptation, temperature exposures were defined using municipality-specific percentiles, with low and high temperatures corresponding to the 2.5th and 97.5th percentiles, respectively. MAIN OUTCOMES AND MEASURES: The primary outcome was all-cause and cardiovascular mortality among patients with heart failure. RESULTS: The mean (SD) age at death among patients with heart failure was 84.3 (9.4) years, with 121 061 female patients (48.3%). Short-term exposure to ambient temperature demonstrated a U-shaped association with both all-cause and cardiovascular mortality. For all-cause mortality, odds ratios (ORs) were 1.130 (95% CI, 1.074-1.189) for low temperatures and 1.054 (95% CI, 1.017-1.093) for high temperatures over the entire study period. For cardiovascular mortality, low temperatures were associated with an OR of 1.160 (95% CI, 1.083-1.242) over the entire study period, and high temperatures with an OR of 1.084 (95% CI, 1.014-1.159) during 2014-2021. The mortality risk associated with high temperatures was more pronounced during the 2014-2021 period compared to 2006-2013. Male patients, those with comorbid diabetes, and diuretic users were more susceptible to low temperatures, whereas high temperature was more strongly associated with mortality in patients with comorbid atrial fibrillation or flutter and those exposed to elevated ozone levels. CONCLUSIONS AND RELEVANCE: This nationwide Swedish time-stratified case-crossover study indicates that short-term exposure to both low and high temperatures was associated with increased risk of all-cause and cardiovascular mortality in patients with heart failure. The mortality risk associated with high temperatures appears to be increasing over time, emphasizing the need for adaptation, even in high-latitude regions.