Atrial Cardiomyopathy (AtCM)
Definition
Atrial cardiomyopathy (AtCM) is defined as "electrical and mechanical dysfunction of the atria, resulting from underlying pathological changes that lead to atrial enlargement or atrial fibrosis, with the potential to produce clinical consequences." (ESC/HFA 2025 consensus)
It is a graded, progressive disorder spanning from apparently healthy atria, through a subclinical phase of atrial disease, to end-stage atrial failure. AtCM can be primary (without relevant initial cardiac abnormalities) or secondary (to ventricular and/or valvular disease). (sources/atrial-cmp-esc-2025, rating: high)
Key Concepts
Diagnostic Framework
AtCM diagnosis requires two components to avoid over-diagnosis: (sources/atrial-cmp-esc-2025, rating: high)
- Electrical atrial dysfunction (P-wave score ≥1) — mandatory
- At least one of:
- Mechanical atrial dysfunction (impaired LA strain/function)
- Atrial enlargement (elevated LAVi or LA diameter)
- Excessive atrial fibrosis (CMR-LGE ≥10–15%)
This requirement for both electrical and structural/functional evidence represents the key advance over prior definitions, which relied on single markers and risked over-diagnosis.
P-Wave Scoring System (Electrical Atrial Dysfunction)
| Score | P-wave Finding |
|---|---|
| 0 | No changes — AtCM unlikely |
| 1 | Prolonged P-wave duration (≥120 ms standard ECG or ≥150 ms amplified 12-lead ECG); also partial IAB, abnormal voltage ≤0.1 mV, axis <0° or >75°, PTF-V1 >40 mm/ms, dispersion >40 ms |
| 2 | Advanced IAB (P-wave ≥120 ms + biphasic morphology in ≥2 inferior leads) without clinical atrial arrhythmia |
| 3 | Advanced IAB with paroxysmal atrial arrhythmia |
| 4 | Persistent atrial arrhythmia |
- Score 1–2: At risk for AtCM; proactive comorbidity management; anticoagulation/antiarrhythmics not established
- Score ≥3: Evaluate thromboembolic risk; anticoagulation and antiarrhythmic strategies per clinical guidelines
Inter-Atrial Block (IAB)
- IAB defined as P-wave duration ≥120 ms; classified as partial (≥120 ms, positive/bimodal inferior leads), advanced (≥120 ms + biphasic in ≥2 inferior leads), or intermittent
- Advanced IAB = Bayes syndrome when associated with new-onset supraventricular arrhythmias
- AF risk: 2× with partial IAB, 4× with advanced IAB
- Associated with ischaemic stroke, cognitive impairment, HF, and mortality
- Advanced IAB reflects late-stage AtCM; early detection requires combining IAB with other sensitive P-wave parameters (sources/atrial-cmp-esc-2025, rating: high)
Imaging Criteria for AtCM (Table 3 Summary)
| Parameter | 2D Echo Threshold | CMR Threshold |
|---|---|---|
| LAVi | >40 ml/m² (>48 ml/m² women >65 yr) | >60 ml/m² |
| LASr (reservoir strain) | <23% | <23% |
| LA booster strain | <8% | <8% |
| LA conduit strain | <12% (<9% in >65 yr) | <21% |
| LA emptying fraction | <48% | <46% |
| LA diameter | >40 mm men / >38 mm women | >42 mm men / >41 mm women |
Only LAVi and LASr are incorporated in the 2025 AtCM diagnostic framework — others lack sufficient evidence to inform decision-making at this stage. (sources/atrial-cmp-esc-2025, rating: high)
LASr: More closely associated with stroke and dementia risk than AF itself. In HFpEF, mechanical atrial dysfunction (not AF) is an independent and better predictor of adverse clinical outcomes. (sources/atrial-cmp-esc-2025, rating: high)
Atrial Fibrosis Detection
- CMR late gadolinium enhancement (LGE): LA LGE ≥10–15% predicts incident atrial arrhythmias, stroke, and ablation recurrence after pulmonary vein isolation
- Limited by spatial resolution of current CMR in relation to the thin atrial wall; variable acquisition/post-processing protocols mean detected LGE percentages are not comparable across centres
- LASr correlates with histological atrial fibrosis in advanced HF — echocardiography may serve as a surrogate measure (sources/atrial-cmp-esc-2025, rating: high)
- See concepts/Late-Gadolinium-Enhancement for technical detail
Common Soil Hypothesis
The 'common soil hypothesis' proposes that shared stressors — ageing, cardio-metabolic risk factors (hypertension, obesity, diabetes mellitus), and concomitant diseases — promote atrial disease through inflammation, endothelial and microvascular dysfunction, fibrosis, hypercoagulability, and atrial stretch. AtCM thus becomes a specific clinical entity and potentially targetable indicator of adverse prognosis, even in the absence of clinically detected AF or HF. (sources/atrial-cmp-esc-2025, rating: high)
Biomarkers
- BMP10 (bone morphogenetic protein 10): atrial-specific ligand; elevated levels reflect more severely altered atrial structure; linked to adverse CV events, higher AF recurrence after rhythm control, and late postoperative AF
- Mid-regional proANP: emerging specific biomarker for AtCM in HFpEF; thresholds require further research
- ANP: defective in failing atrium; anti-hypertrophic, anti-arrhythmic, and autophagy-stimulating; excessive ANP production can paradoxically lead to isolated atrial amyloidosis
- BNP/NT-proBNP: utility for AtCM unclear; ARCADIA trial (BNP >250 pg/ml + PTF-V1 as AtCM markers; apixaban vs aspirin for cryptogenic stroke prevention) was stopped early for futility (sources/atrial-cmp-esc-2025, rating: high)
Molecular Mechanisms
- NLRP3 inflammasome: Activated by metabolic/cardiovascular disorders → IL-1β/IL-18 release → fibro-inflammatory cycle in atrial cardiomyocytes, immune cells, fibroblasts → creates and perpetuates AF substrate. Largest colchicine RCTs show no significant AF prevention — conventional anti-inflammatory therapy has mixed results. (sources/atrial-cmp-esc-2025, rating: high)
- Atrial fibrosis mechanisms: Stretch-activated fibroblasts, systemic inflammation, coagulation factor activation, and fibro-fatty infiltrations. Diffuse endomysial fibrosis → discontinuous conduction; patchy fibrosis → macro re-entrant circuits. (sources/atrial-cmp-esc-2025, rating: high)
- Electrical remodeling: Shortened AERP; novel targets include PDE8B2 inhibition, SK current upregulation, CaMKIIδc activation. (sources/atrial-cmp-esc-2025, rating: high)
- Epicardial adipose tissue (EAT): Pro-inflammatory and pro-fibrotic paracrine signaling, atrial fat infiltration, ion channel alteration, gap junction modulation, autonomic dysfunction. More atrial EAT when AF co-occurs with HFpEF. EAT browning may offer protection in some contexts. Negative effects more pronounced in women. (sources/atrial-cmp-esc-2025, rating: high)
- Ca²⁺ handling: Ca²⁺ triggered activity is the major AF trigger in HFrEF; atrial cardiomyocytes show Ca²⁺ handling (not electrical) remodeling in HFrEF unless AF co-occurs; fatty acid metabolism defects in atrial cardiomyocytes in AF and HFpEF. (sources/atrial-cmp-esc-2025, rating: high)
Role of Right Heart and Comorbidities
- Right heart dysfunction may contribute to LA myopathy via enhanced left-to-right atrial interaction and heightened pericardial constraint — the concept of 'disproportionate LA myopathy' in HFpEF
- Tricuspid regurgitation causing RV volume overload may also lead to HFpEF and atrial myopathy
- Comorbidities (hypertension, diabetes, obesity, CAD, moderate-to-severe MR, CKD, age >65) reduce LA and RA strain parameters in paroxysmal AF, especially when ≥3 are present (sources/atrial-cmp-esc-2025, rating: high)
Management
- No dedicated AtCM RCTs exist — current management is based on risk factor reduction and comorbidity management
- Parallels the AF-CARE approach: aggressive management of hypertension, diabetes, obesity, exercise, and alcohol restriction (Class I recommendations in clinical AF; extrapolated to AtCM)
- SGLT2 inhibitors and GLP-1 receptor agonists have known antifibrotic properties; their specific impact on atrial fibrosis and AtCM progression is under investigation
- LA enlargement is preventable through up-titration of ACEi/ARB and SGLT2i in HF patients (sources/atrial-cmp-esc-2025, rating: high)
- When AtCM + confirmed HF or persistent AF → atrial failure: treat each condition per respective ESC guidelines; cardiologist with HF or AF expertise recommended
Contradictions / Open Questions
- AtCM framework vs. AF-first diagnostic paradigm: Current AHA/ESC AF staging positions AF as the primary entity; AtCM framework positions AF as a late manifestation or consequence of underlying atrial disease. This re-frames the relationship between AF and stroke — LA size and LASr predict stroke better than AF episodes per se, challenging AF-centric risk stratification. (sources/atrial-cmp-esc-2025, rating: high)
- ARCADIA trial futility (apixaban vs. aspirin in AtCM-defined cryptogenic stroke): Stopped early with no benefit — raises the question of whether the AtCM markers used (BNP >250 pg/mL or PTF-V1 >40 mm/ms) adequately identified the subgroup that would benefit from anticoagulation, or whether anticoagulation in AtCM without AF truly lacks efficacy. (sources/atrial-cmp-esc-2025, rating: high)
- Anticoagulation in AtCM without AF: Not established; colchicine showed no AF prevention in largest RCTs; anticoagulation thresholds require dedicated trials
- AtCM diagnostic framework is not yet clinically validated: No prospective trial has tested whether diagnosing AtCM earlier changes outcomes
- Atrial LGE quantification: No standardised acquisition/post-processing protocol; variable results across centres; LA LGE ≥10–15% threshold not validated in large prospective cohorts
- Gender differences: Women have higher prevalence of LA low-voltage zones than men at diagnosis, suggesting earlier/more advanced AtCM at presentation; sex-specific cut-offs, thresholds, and mechanisms are understudied (sources/atrial-cmp-esc-2025, rating: high)
Connections
- Related to concepts/Atrial-Failure — end-stage AtCM
- Related to entities/Atrial-Fibrillation — AF is a late manifestation and consequence of AtCM
- Related to entities/Heart-Failure — bidirectional; HFpEF especially
- Related to concepts/HFpEF — mechanical atrial dysfunction better predictor than AF in HFpEF
- Related to concepts/Late-Gadolinium-Enhancement — atrial fibrosis detection
- Related to concepts/AF-CARE — comorbidity management parallels
- Related to concepts/AF-Staging — AtCM framework predates AF staging
- Related to concepts/Atrial-Myopathy-in-HCM — specific genetic subset of AtCM
- Related to concepts/Subclinical-AF — pre-AF stage, early detection