Table 1.
ECG findings, their pathogenesis, and meaning in cardiomyopathies
| ECG findings | ||||
|---|---|---|---|---|
| Disease | Pathogenesis/electrogenesis | Prevalence | Disease stage | Prognostic/therapeutic implications |
| P wave | ||||
| HCM | LA and/or RA dilation | 92% [2] | P wave prolongation associated with the severity of HCM phenotype [2] | |
| DCM | LA and/or RA dilation |
72% (if LA dilatation) 15% (if RA dilatation) [3] |
||
| Long PR interval and AV blocks | ||||
| AFD | Accumulation of glycosphingolipids | 6–11% [93] | First-degree AV block may disappear following ERT [15] | |
| CA | Accumulation of amyloid and fibrous tissue |
21% (1st degree), 3% (2nd–3rd degree) [4] Higher prevalence in ATTR-CA (1st degree AV block in 18% patients with AL-CA but up to 33% of those with ATTRwt-CA and 25% for ATTRv) [5] |
Same indications to PM implantation than in other disease settings [94] | |
| KSS | Greater mutation load in AV node | 84% [95] | High risk of complete AV block and SCD [94] | |
|
Neuromuscular diseases: Emery-Dreifuss DM type 1 DM type 2 |
Up to 20% [96] |
‐ Emery-Dreifuss dystrophy: risk of AV block and SCD [97] ‐ DM type 1: risk of AV block and SCD [6] ‐ DM type 2 usually leads to mild AV or BBB, but arrhythmias and SCD have been reported [7] |
||
| Cardiac sarcoidosis | Granulomatous inflammation affecting the conduction system | 34% among middle-aged patients with unexplained AV block [11] | ||
| Laminopathy | Fibrosis in the AV node | Early | Higher risk of life-threatening arrhythmias [9] | |
| LVNC | 3–25% [13] | |||
| Short PR | ||||
| Danon disease | Accelerated nodal conduction, disruption of the annulus fibrosus by glycogen-filled myocytes | 70% in M [17] | Risk of lethal arrhythmias and SCD following atrial tachyarrhythmias [17] | |
| Pompe disease | 10% [18] | The short PR interval can normalize after ERT (in infantile disease) [18] | ||
| PRKAG2 syndrome | 68% [20] | Risk of lethal arrhythmias and SCD (high-degree AV block or fast conduction of atrial tachyarrhythmias) [20] | ||
| AFD | Stored glycosphingolipids increasing conduction velocity | 15–40% [98] | Early [93] | The short PR interval can normalize after ERT [15] |
| Mitochondrial disease | Proliferation of mitochondria altering cardiomyocyte functioning | 22% [21] | PM implantation may be considered in KSS | |
| Atrial fibrillation | ||||
| HCM | Atrial enlargement and fibrosis | 17–30% [24, 25] | Higher risk of all-cause mortality, cardiac death, SCD and stroke-related death [23, 26, 27] | |
| DCM | 36–76% [23, 24, 28–32] | |||
| ACM | Desmosomal dysfunction and RA enlargement or dysfunction | 9–30% [33, 34] | AF predicts worse outcomes in patients with right-sided ACM [36] | |
| LVNC | 1–29% [23, 24, 37, 38] | Lower incidence in children | AF is associated with LVNC severity and predicts survival [39] | |
| CA | Amyloid infiltration promoting atrial fibrosis and dilation |
Higher prevalence in ATTR- than AL-CA |
AF does not seem to predict a worse outcome [44, 45] | |
| Q waves | ||||
| HCM | Myocardial fibrosis and septal hypertrophy displacing the septal electrical vector | 18–53% [46, 53] | Early | May precede the increase in LV mass by several years, are less common in patients with biventricular hypertrophy, and help differentiate HCM from the athlete’s heart |
| CA | Accumulation of amyloid and fibrosis |
25–47% in AL-CA |
Independently predict death in patients with AL-CA [99] | |
| Idiopathic DCM | Vector displacement due to LV dilation and transmural fibrosis | 10–25% [3, 48] | ||
| Dystrophin cardiomyopathy | Scarring of the posterolateral region of the LV | 21% (DMD) [100], 42% (BMD) [101] | ||
| QRS complex: high voltages | ||||
| HCM | Cardiomyocyte hypertrophy | 41–60% [46, 53] |
Scores including QRS amplitude were proposed to predict SCD [55] Mavacamten may relieve ECG signs of LVH |
|
| DCM | LVH | 17–69% [56, 57] | Unclear prognostic relevance | |
| CA | LV apex spared by amyloid accumulation | Up to 25% in ATTR-CA [58] | No relationship with outcome [49] | |
| Pompe disease, Danon disease, FD | Accumulation of glycosphingolipids | 6–10% (less common in Pompe than in Danon and AFD) [59] | ||
| QRS complex: low voltages | ||||
| HCM | Extensive fibrosis | < 3% [61] | End-stage | Higher risk of SCD [61] |
| DCM | Loss of vital myocardium and diffuse LV fibrosis | 3–6% [3, 63] | Higher risk of death or heart transplantation, SCD, or life-threatening ventricular arrhythmias [3] | |
| ACM | Fibro-fatty replacement |
41% with LV involvement 17% without LV involvement [63] |
Advanced | Higher risk of life-threatening ventricular arrhythmias and SCD [67] |
| CA | Amyloid and fibrosis | 46–70% (higher in AL-CA) [68, 69] | Higher risk of CV death [69] | |
| QRS fragmentation and epsilon wave | ||||
| HCM | Myocardial disarray, interstitial fibrosis, conduction impairment | 75% [73] | Higher risk of ventricular tachyarrhythmias and SCD (++ in 3 coronary artery territories) [73] | |
| DCM | Myocardial scar | 23–26% [74] | Higher risk of ventricular tachycardias and all-cause death [74] | |
| Cardiac sarcoidosis | Myocardial granulomas | 50% [102] | Early | Association with LGE presence [102] |
| ACM | Fibro-fatty replacement in the subepicardial region of the RV free wall | 85% [103] | QRS fragmentation: higher risk of VT, VF, and appropriate ICD discharges [78]. Epsilon waves in aVR: higher risk of HF hospitalization, HF-related death, SCD, and heart transplantation [76] | |
| RBBB | ||||
| HCM | 4–5% [79] | One-third of patients develop complete heart block after myectomy [79] | ||
| AFD | 22% [14] | |||
| DCM | 7% [80] | Predictor of all-cause mortality [80] | ||
| ACM | 19 [82] to 32% [81] in ARVC | |||
| LBBB | ||||
| HCM | 2% [83], 22% in end-stage HCM [84], up to 40% after septal myectomy [85] | LBBB after surgery not associated with worse outcome [79] | ||
| DCM | Degeneration or fibrosis of the conduction system | 25–30% [87] |
No worse survival in patients with DCM and LVEF 36–50% [87] Shorter survival in patients with idiopathic DCM developing LBBB [88] |
|
| ST segment and T waves | ||||
| HCM |
- Epicardial cardiomyocytes depolarize and repolarize later than endocardial cardiomyocytes - ST-segment elevation may signal ventricular aneurysm |
Early |
Negative T waves in V3–V6 becoming positive may denote the development of an apical aneurysm STEMI patterns associated with higher risk of SCD [61] |
|
| DCM | T wave inversion in 62% of patients with FLNC mutations [104] | |||
| Right-side ACM | Fibro-fatty infiltration in the subepicardium |
- Negative T wave strongly related to disease presence - ST segment elevation with negative T wave in V1–V2 related to advanced transmural RV involvement [92] |
||
| CA | Amyloid infiltration | |||
| AFD | Asymmetrical negative T waves and ST-T segment depression or elevation in inferolateral leads related to fibrosis | |||
| Mitochondrial diseases | Asymmetrical negative T waves in 50% [21] | |||
ACM arrhythmogenic cardiomyopathy, AF atrial fibrillation, AFD Anderson-Fabry disease, AL light chain amyloidosis, ATTR transthyretin amyloidosis, AV atrioventricular, BBB bundle branch block, BMD Becker muscular dystrophy, CA cardiac amyloidosis, DCM dilated cardiomyopathy, DM myotonic dystrophy, DMD Duchenne muscular dystrophy, DMD dystrophin gene, ECG electrocardiogram, ERT enzyme replacement therapy, FLNC filamin-C gene, HCM hypertrophic cardiomyopathy, HF heart failure, ICD implantable cardioverter-defibrillator, KSS Kearns-Sayre syndrome, LA left atrium, LBBB left bundle branch block, LGE late gadolinium enhancement, LMNA lamin A/C, LV left ventricle, LVH left ventricular hypertrophy, LVNC left ventricular non-compaction cardiomyopathy, M male, PM pacemaker, PRKAG2 protein kinase AMP-activated non-catalytic subunit gamma 2, QTc corrected QT, RA right atrium, RBBB right bundle branch block, RV right ventricle, SCD sudden cardiac death, SCN5A sodium voltage-gated channel alpha subunit 5 gene, v variant, STEMI ST elevation myocardial infarction, VF ventricular fibrillation, VT ventricular tachycardia, wt wild-type