Daily Cardiology Research Analysis

BACKGROUND AND AIMS: Atrial fibrillation (AF) is frequently classified by episode duration and cumulative burden, yet these methods fail to characterize temporal episode distribution (AF density), which may be more clinically relevant and prognostically important. This study evaluated AF density's association with ischaemic stroke and whether it improves risk stratification compared with AF burden. METHODS: Data from two US cohorts with cardiac implantable electronic devices remotely monitored by the Veterans Health Administration and University of North Carolina (January 2010-May 2025) were analysed. AF burden (percentage of time in AF) and density [range: 0 (dispersed episodes) to 1 (consolidated episodes)] were assessed in 30-day intervals and categorized as low (>0-0.3), medium (>0.3-0.6), medium-high (>0.6-0.9), and high (>0.9-1.0). Patients with permanent AF or no episodes ≥6 min were excluded. G-formula modelling estimated 1-year stroke risk ratios (RRs), adjusting for baseline and time-varying covariates. Results were pooled using random-effects meta-analysis. RESULTS: Of 41 780 patients, 12 868 met inclusion criteria (mean age 72.0 years; median CHA2DS2-VASc 4.0); 336 experienced ischaemic stroke over a median 4.0-year follow-up (6.3 per 1000 person-years). Atrial fibrillation density demonstrated a dose-response relationship with 1-year stroke risk (RR 1.75; 95% confidence interval 1.25-2.44) and findings were consistent across device types, comorbidities, age, and anticoagulation status. At each level of AF burden, patients with high density exhibited greater stroke risk. CONCLUSIONS: Atrial fibrillation density demonstrated robust dose-response relationships with ischaemic stroke independent of AF burden and enhanced risk stratification, suggesting that density may enable more precise stroke risk assessment and personalized prevention strategies.

Breast arterial calcification (BAC) is commonly observed on screening mammography and may provide a low-cost opportunistic marker to enhance cardiovascular risk assessment in women, in whom cardiometabolic risk is often underrecognized by traditional scores. We performed a PRISMA-guided systematic review and meta-analysis of PubMed, Embase, Scopus, and ClinicalTrials.gov through April 30, 2025 to evaluate the association between BAC and both future cardiovascular events and underlying coronary pathology. Cohort studies reporting adjusted hazard ratios (HRs) for incident cardiovascular events were pooled using random-effects meta-analysis, with prespecified subgroup analyses by BAC ascertainment method and study design, while additional studies reporting odds ratios (ORs) for coronary artery disease (CAD) or coronary artery calcium (CAC) were synthesized separately. Four cohort studies including approximately 25,000 women with 6-12 years of follow-up demonstrated that BAC was associated with significantly higher incident cardiovascular events (pooled HR 1.82, 95% CI 1.37-2.43; p<0.001), with the strongest association observed for radiologist-reported BAC and concordant findings across artificial intelligence-derived and densitometric measures, and no evidence of small-study effects. Across OR-based analyses including approximately 5,000 women, BAC was strongly associated with underlying coronary pathology, with a pooled adjusted OR of 4.00 (95% CI 2.44-6.56) for CAD and similarly elevated odds for CAC. In conclusion, BAC detected on routine mammography identifies women at substantially higher future cardiovascular risk and is strongly associated with subclinical coronary disease, supporting its potential role as a scalable, no-added-cost marker to enhance cardiovascular risk assessment in women.

AIMS: Left bundle branch block (LBBB) is associated with mechanical dyssynchrony, heterogeneous perfusion, and adverse left ventricular (LV) remodeling. However, not all patients with LBBB develop cardiomyopathy, and dyssynchrony can occur without conduction defects. The role of microvascular dysfunction remains uncertain. We aimed to assess how mechanical dyssynchrony and perfusion heterogeneity relate to LV remodeling and function in patients with and without LBBB. METHODS AND RESULTS: We analyzed 233 patients with LBBB and 932 matched controls who underwent PET myocardial perfusion imaging, assessing mechanical dyssynchrony (phase entropy), LV volumes, and ejection fraction (EF); coronary vascular resistance (CVR), myocardial blood flow (MBF), myocardial flow reserve (MFR) as markers of microvascular function; and septal-to-lateral MBF ratio (SLR) as a measure of regional perfusion heterogeneity. Compared with controls, LBBB patients had greater dyssynchrony (56% vs. 40%), larger LV volumes, and lower EF (54% vs. 67%) (all p<0.001), as well as higher stress CVR (37 vs. 34 mmHg/mL·min⁻¹·g⁻¹), and lower MBF (2.4 vs. 2.6 mL/min/g), MFR (2.4 vs. 2.6), and SLR (0.95 vs. 1.00) (all p<0.05). Among patients with dyssynchrony, SLR<1.0 identified greater remodeling. In multivariable regression, phase entropy and SLR independently predicted LV volumes and EF, with adverse effects of SLR reduction amplified in LBBB (interaction p<0.01). In Cox analysis, phase entropy (HR:1.02, p=0.01), MFR (HR:0.62, p<0.001), and LVEF (HR:0.97, p<0.001) were independently associated with death or heart failure hospitalization, whereas LBBB was not. CONCLUSIONS: Mechanical dyssynchrony and perfusion heterogeneity independently predict adverse LV remodeling, irrespective of LBBB. Integrated imaging improves cardiomyopathy stratification.