Rapid Fire Session

Session: Rapid Fire Session 2: Multi-Center Trials and Epidemiological Studies (Monitor 12)

Defining and Validating a Cutoff for the Left Atrioventricular Coupling Index (LACI) by Cardiovascular Magnetic Resonance in the German National Cohort (NAKO)

Thursday, February 5, 2026

4:20 PM - 4:27 PM

Location: Galapagos / Aruba / Ilhabela (2nd Lower Level)

Presenting Author(s)

JG

Jan Gröschel, MD

MD
Charite
Berlin, Berlin, Germany

Primary Author(s)

JG

Jan Gröschel, MD

MD
Charite
Berlin, Berlin, Germany

Co-Author(s)

Clemens Ammann, MD

Physician
Charité – Universitätsmedizin Berlin
Berlin, Berlin, Germany
LG

Leonhard Grassow

Medical student
Charité – Universitätsmedizin Berlin, Germany
SR

Susanne Rospleszcz, PhD

Principal Investigator
Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany, Germany
TP

Tobias Pischon, MD, MPH

Principal Investigator
Molecular Epidemiology Research Group, Max Delbrück Center for Molecular Medicine in the Helmholtz Association, Berlin, Germany
Berlin, Berlin, Germany
CS

Christopher Schuppert, MD

Attending Physician
Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
Freiburg, Baden-Wurttemberg, Germany
Christopher L. Schlett, MD, MPH

Deputy Director
Medical Center – University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg, Germany
Freiburg, Baden-Wurttemberg, Germany
Jeanette Schulz-Menger, MD

Head Working Group Cardiac MRI
Charité/ University Medicine Berlin and Helios
Berlin, Berlin, Germany

Background: The left atrioventricular coupling index (LACI) has emerged as a predictor of outcomes such as heart failure, atrial fibrillation, cardiovascular death, and prognosis after myocardial infarction (1-3). However, general reference ranges remain unvalidated due to a lack of healthy cohorts. This study addresses this gap using multi-center cardiovascular magnetic resonance (CMR) data from the large, prospective German National Cohort (NAKO).

Methods: We analyzed CMR data from N = 29,035 participants in the NAKO study that included two- and four-chamber cine long-axis views. The left atrioventricular coupling index (LACI) was calculated as the ratio of minimal left atrial (LA) volume to left ventricular (LV) end-diastolic volume (EDV), with volumes obtained from artificial intelligence-assisted segmentations (cvi42, Circle Cardiovascular Imaging, Calgary, Canada). Participants with implausibly low chamber volumes, as defined for the lower limit by Kawel-Boehm et al. (4) were excluded (LA volume < 2/3 ml [men/women]; LV EDV < 81/68 ml [men/women]), resulting in N = 27,173 cases. To establish a normal reference range, we defined a healthy subcohort by excluding individuals with any history of cardiovascular disease, diabetes mellitus or measured HbA1c ≥ 48 mmol/mol, hyperlipidaemia or LDL-cholesterol ≥ 3.0 mmol/l, kidney disease or serum creatinine ≥ 106/88 µmol/l (men/women), or cancer. Additional exclusions applied to current smokers, individuals with systolic/diastolic blood pressure > 140/90 mmHg, body mass index < 18.5 or > 30 kg/m², LV ejection fraction < 50%, LV EDV > 204/158 ml (men/women), and maximal LA volume > 55/45 ml (men/women). The resulting healthy subcohort comprised N = 2,855 participants.

Results: In the overall cohort (N = 27,173), the mean LACI was 15.5 ± 6.6% and increased progressively with age (Figure 1). In the healthy subcohort, the mean LACI was 13.9 ± 4.7%, with the 95th percentile corresponding to a cutoff value of 26.0%. Applying this threshold to the remaining study cohort, we identified N = 1,322 individuals with a LACI ≥ 26%. Comparison between participants with LACI < 26% and those with LACI ≥ 26% (Table 1) revealed that the latter group was significantly older and had a higher proportion of women. Cardiovascular risk factors, particularly arterial hypertension and arrhythmia were more prevalent in the LACI ≥ 26% group. Examples are given in Figure 2.

Conclusion: In this NAKO CMR study, we defined a reference range for LACI and set a 26% cutoff from the 95th percentile of a healthy subcohort. Applying this threshold in the general population identified older, predominantly female individuals with more hypertension and arrhythmias. Elevated LACI may thus be a non-invasive marker of adverse cardiovascular phenotype and merits further study for risk stratification

Comparison of basic characteristics and cardiometabolic risk

	LACI < 26% (N=25,851)	LACI ≥ 26% (N=1,322)	*p-values*
Sex	43.2% female	56.6% female	< 0.001
Age [years]	47.7 ± 12.1	59.5 ± 7.9	< 0.001
BMI [kg/m²]	26.5 ± 4.6	29.2 ± 5.5	< 0.001
Systolic BP [mmHg]	127.3 ± 15.7	134.1 ± 18.9	< 0.001
Diastolic BP [mmHg]	78.9 ± 9.9	80.5 ± 10.6	< 0.001
HbA1c [mmol/mol]	35.8 ± 6.0	39.1 ± 7.6	< 0.001
LDL-cholesterol [mmol/l]	3.3 ± 0.9	3.4 ± 0.9	< 0.001
Serum Creatinine [µmol/l]	73.8 ± 15.2	73.1 ± 17.6	0.101
Diabetes	4.0 %	11.0 %	< 0.001
Hyperlipidaemia	21.4 %	37.1 %	< 0.001
Hypertension	22.7 %	52.6 %	< 0.001
Kidney disease	1.7 %	3.0 %	0.002
Current Smoker	18.7 %	15.4 %	0.011
Former Smoker	30.2 %	39.1 %	< 0.001
Myocardial infarction	0.3 %	1.3 %	< 0.001
CAD or angina pectoris	0.7 %	3.0 %	< 0.001
Arrhythmia	6.4 %	17.1 %	< 0.001
Heart failure	1.2 %	4.2 %	< 0.001
Peripheral artery disease	0.9 %	2.5 %	< 0.001
Thyroid disease	18.9 %	29.9 %	< 0.001
Cancer	5.0 %	10.3 %	< 0.001

LACI, left atrioventricular coupling index; BMI, body mass index; BP, blood pressure; HbA1c, glycohemoglobin; LDL, low density lipoprotein; CAD, coronary artery disease.Figure 1: Left-atrial coupling index (LACI) by age and sex. First row: solid line: linear regression; dotted line: median; shaded area: interquartile range. Second row: bivariate histograms and 26% cutoff for LACI.
Figure 2: Examples of high and low left-atrial coupling index (LACI)