Österberg AW, Östman-Smith I, Jablonowski R, Carlsson M, Green H, Gunnarsson C, Liuba P, Fernlund E. Pediatr Cardiol. 2021 Jan 30. doi: 10.1007/s00246-020-02506-9. PMID: 33515326
Take Home Points:
- An ECG risk-score has been described that predicts high risk of subsequent cardiac arrest in young patients with hypertrophic cardiomyopathy (HCM). We assessed whether an ECG risk-score could be used as an indicator of myocardial fibrosis.
- 12-lead ECG was used for calculating the ECG risk-score (grading 0–14p).
- High-risk ECG (risk-score>5p) occurred only in the HCM group.
- In low-risk ECG-score patients (0–2p), median percent of myocardium showing LGE were zero percent, in intermediate-risk (3–5p) were 5.4% and in high-risk (6–14p) were 10.9%
- ECG-score>2p had a sensitivity and specificity of 79% and 84% to detect positive LGE on CMR.
- ECG risk-score>2 p could be used as a cut-off for screening of myocardial fibrosis.
Commentary from Dr. Manoj Gupta (New York, USA), section editor of Pediatric & Fetal Cardiology Journal Watch:
Hypertrophic cardiomyopathy (HCM) is the most common inherited cardiac disease and the leading cause of sudden cardiac death in the young. Several studies by cardiac magnetic resonance (CMR) in HCM patients have shown the gradual and progressive changes of the myocardium with findings of disturbed myocardial perfusion and perfusion defects in the surroundings of fibrotic areas. Myocardial fibrosis as measured by CMR has been proposed as a risk-factor for cardiac events. CMR with late gadolinium enhancement (LGE) is gold standard for evaluating fibrosis in HCM.
The study groups consisted of 42 individuals: 26 HCM patients, seven individuals at risk of HCM (genotype-positive, phenotype-negative and first-degree relatives) and nine healthy volunteers, including four athletes (physical activity>10 h/week), without heredity for cardiac disease. The 14 gene standard panel for HCM in the HCM group was positive in 16 patients but the genetic mutations were unknown in 10 patients.
It was possible to calculate the ECG risk-scores in all study participants (n=42). High-risk ECG-scores (6–14 p) were found in 35% of the HCM patients (9/26) but in none of the individuals at risk of HCM, nor in healthy volunteers.
LGE could be evaluated in all individuals (n=42). All LGE-positive individuals were in the HCM group. In the HCM group 54% of the individuals (14/26) had positive LGE, with median ECG risk-score of 8p [4–11p]. Among the HCM patients with a high-risk ECG-score, 89% had positive LGE (8/9). The one exception, the patient with negative LGE and a high-risk ECG-score, had HCM due to a PRKAG2 mutation and not a sarcomeric mutation.
Three HCM patients had a very low-risk ECG (0–2p): One HCM patient had a 2.3% LGE of LVM but a completely normal ECG, one HCM patient had an ECG risk-score of 1 point and 4%LGE of LVM and one HCM patient had 2 points and 2.1% LGE of LVM. The individual with normal ECG and 2.3% LGE of LVM was diagnosed with mild HCM two years before the CMR, had a known genetic predisposition with MYBPC3 where the ultrasound showed IVS and PW measurements at 14 mm. Three individuals had an intermediate-range ECG risk-score (3–5p): One HCM patient (14 years) had a score of 3 points and 13.5% LGE of LVM, one HCM patient (30 years) had 4 points and 20.3% LGE of LVM and one patient (13 years) had 5 points and 5.4% LGE of LVM.
The positive and negative predictive value (PPV and NPV) of an ECG risk-score>2 points as a screening test for LGE shows a PPV of 79% [CI 56–91%] and NPV of 84% [CI 66–94%] for LGE being present in patients.
In the HCM group 62% (13/21) had a perfusion defect (PD). The median ECG risk-score in HCM patients with a perfusion defect was 5p [1–9p] and in HCM patients without a perfusion defect 0p [0–1p], p=0.001. All individuals positive for perfusion defect were in the HCM group. An ECG risk-score>2 points was associated with positive PD present on CMR.
This study showed that conventional 12-lead ECG analyzed by the ECG risk-score method according to Östman-Smith et al. has high specificity and sensitivity for indicating myocardial fibrosis as well as perfusion defects on CMR. Thus, ECG risk-score>2p is an inexpensive and easily available method as a screening for HCM patients with likely myocardial fibrosis and/or perfusion defects. An ECG risk-score>2 points in our study predicted myocardial fibrosis on CMR by late gadolinium enhancement with a specificity of 84% and a sensitivity of 79%. An ECG risk-score>2 points also predicted myocardial perfusion defect with high sensitivity and specificity.
These findings indicate that the ECG risk score could be used as a screening tool for HCM patients for predicting who is at risk of having myocardial fibrosis and need urgent further risk stratification investigations.
Implications for the Future: This study shows the ability of the ECG risk-score in predicting fibrosis and perfusion defects on CMR. Further and larger studies are needed to validate if ECG risk-score and LGE on CMR have independent prognostic value in the clinical follow-up of HCM in the young.
Conclusion: Conventional 12-lead ECG analyzed and categorized by the ECG risk-score may predict myocardial fibrosis and perfusion defects as measured by CMR in HCM in the young. An ECG risk-score>2 points could be used as a cut-off for screening of myocardial fibrosis and/or perfusion defects with high sensitivity and specificity. None of the genotype positive, phenotype-negative individuals at risk for HCM demonstrated LGE or perfusion defects on CMR or a high ECG risk-score, nor did the healthy volunteers.