T-wave inversions related to left ventricular basal hypertrophy and myocardial fibrosis in non-apical hypertrophic cardiomyopathy: A cardiovascular magnetic resonance imaging study

Electrocardiographic associations with myocardial fibrosis among sudden cardiac death victims

OBJECTIVE

A major challenge in reducing the incidence of sudden cardiac death (SCD) is the identification of patients at risk. Myocardial fibrosis has a substantial association with SCD risk but is difficult to identify among general populations. Our aim was to find electrocardiographic (ECG) markers of myocardial fibrosis among SCD victims.

METHODS

Study population was acquired from the Fingesture study, which has gathered data from 5869 consecutive autopsied SCD victims in Northern Finland between 1998 and 2017. The degree of fibrosis was determined in histological samples taken from the heart during autopsy and was categorised into four groups: (1) no fibrosis, (2) scattered mild fibrosis, (3) moderate patchy fibrosis and (4) substantial fibrosis. We were able to collect ECGs from 1100 SCD victims.

RESULTS

The mean age of the study subjects was 66±13 years and 75% were male. QRS duration in ECG correlated with the degree of fibrosis (p<0.001, β=0.153). Prevalence of fragmented QRS complex, pathological Q waves and T wave inversions correlated with increased degree of fibrosis (p<0.001 in each). Depolarisation abnormalities were observed both in ischaemic and non-ischaemic heart disease. Repolarisation abnormalities reached statistical significance only among ischaemic SCD victims. An abnormal ECG was observed in 75.3% of the subjects in group 1, 73.7% in group 2, 88.5% in group 3 and 91.7% in group 4 patients (p<0.001).

CONCLUSIONS

Myocardial fibrosis was associated with QRS prolongation, deep Q waves, T wave inversions and QRS fragmentation. The results provide potentially useful non-invasive early recognition of patients with fibrotic cardiomyopathy and risk of SCD.

Frontal QRS-T angle and left ventricular diastolic function assessed by ECG-gated SPECT in the absence of significant perfusion abnormality

The frontal QRS-T angle, defined as the angle between QRS and T-wave axes, has recently become an area of research interest. We tested the hypothesis that the frontal QRS-T angle is associated with left ventricular (LV) diastolic function in the absence of significant perfusion abnormality using ECG-gated SPECT. One hundred twenty eight patients with no significant perfusion abnormality and preserved LV ejection fraction were enrolled. The peak filling rate (PFR) and the one-third mean filling rate (1/3 MFR) were obtained as LV diastolic parameters on ECG-gated SPECT. There were 115 male and 13 female patients with a mean age of 70 ± 9 years. The PFR and 1/3 MFR were 2.1 ± 0.4/s and 1.2 ± 0.3/s, respectively. The frontal QRS-T angle was 33° ± 31°, ranging from 0° to 151°. There were significant associations of frontal QRS-T angle with PFR (r = - 0.29, p = 0.001) and 1/3 MFR (r = - 0.30, p < 0.001). Multivariate linear regression analysis showed that age (β = - 0.25, p = 0.003), heart rate (β = 0.26, p = 0.002), LV ejection fraction (β = 0.43, p < 0.001) and frontal QRS-T angle (β = - 0.16, p = 0.03) were significant factors associated with PFR. Also, heart rate (β = - 0.32, p < 0.001), LV mass index (β = - 0.19, p = 0.03), LV ejection fraction (β = 0.30, p < 0.001) and frontal QRS-T angle (β = - 0.26, p = 0.002) were significant factors associated with 1/3 MFR. Our data suggested that the frontal QRS-T angle was associated with LV diastolic function in the absence of significant perfusion abnormality.

Correlation of Electrocardiographic Changes with Cardiac Magnetic Resonance Findings in Patients with Hypertrophic Cardiomyopathy

BACKGROUND

Electrocardiogram is the initial test in the investigation of heart disease. Electrocardiographic changes in hypertrophic cardiomyopathy have no set pattern, and correlates poorly with echocardiographic findings. Cardiac magnetic resonance imaging has been gaining momentum for better assessment of hypertrophy, as well as the detection of myocardial fibrosis.

OBJECTIVES

To correlate the electrocardiographic changes with the location of hypertrophy in hypertrophic cardiomyopathy by cardiac magnetic resonance.

METHODS

This descriptive cross-sectional study evaluated 68 patients with confirmed diagnosis of hypertrophic cardiomyopathy by cardiac magnetic resonance. The patients' electrocardiogram was compared with the location of the greatest myocardial hypertrophy by cardiac magnetic resonance. Statistical significance level of 5% and 95% confidence interval were adopted.

RESULTS

Of 68 patients, 69% had septal hypertrophy, 21% concentric and 10% apical hypertrophies. Concentric hypertrophy showed the greatest myocardial fibrosis mass (p < 0.001) and the greatest R wave size in D1 (p = 0.0280). The amplitudes of R waves in V5 and V6 (p = 0.0391, p = 0.0148) were higher in apical hypertrophy, with statistical significance. Apical hypertrophy was also associated with higher T wave negativity in D1, V5 and V6 (p < 0.001). Strain pattern was found in 100% of the patients with apical hypertrophy (p < 0.001).

CONCLUSION

The location of myocardial hypertrophy by cardiac magnetic resonance can be correlated with electrocardiographic changes, especially for apical hypertrophy.

Gender-related differences in the association between serum uric acid and left ventricular mass index in patients with obstructive hypertrophic cardiomyopathy

BACKGROUND

Serum uric acid (SUA) is associated with left ventricular hypertrophy in a wide spectrum of study population. However, whether this association exists in patients with hypertrophic cardiomyopathy (HCM, including obstructive HCM), and if present, whether gender has any impact on this association, remains unknown.

METHODS

A total of 161 patients with obstructive HCM (age 47.2 ± 10.8 years, 99 (62 %) men) were included in this study. All patients underwent extensive clinical, laboratory, echocardiographic, and cardiac magnetic resonance (CMR) imaging examinations. Left ventricular mass index (LVMI) was assessed using CMR.

RESULTS

The mean value of SUA was 353.4 ± 87.5 μmol/L. Both SUA levels (381.2 ± 86.4 vs. 309.0 ± 69.3 μmol/L, p < 0.001) and LVMI (96.2 ± 32.1 vs. 84.4 ± 32.4 g/m(2), p = 0.025) were significantly higher in men than in women. LVMI increased progressively across sex-specific tertiles of SUA in women (p = 0.030), but not in men (p = 0.177). SUA was positively correlated with LVMI in female patients (r = 0.372, p = 0.003), but not in males (r = 0.112, p = 0.269). On multivariate linear regression analysis, SUA was independently associated with LVMI in females (β = 0.375, p = 0.002), but not in males.

CONCLUSIONS

SUA levels are significantly and independently associated with LVMI in women with obstructive HCM, but not in men. Our findings imply the potential significance of urate-lowering regimens in female patients with obstructive HCM.

Significance and Determinants of Cardiac Troponin I in Patients With Obstructive Hypertrophic Cardiomyopathy

Serum cardiac troponins have been demonstrated to have important clinical implications in patients with hypertrophic cardiomyopathy (HC). However, little is known about their roles in patients with obstructive HC. The aim of this study was to explore the clinical significance and determinants of serum cardiac troponin I (cTnI) in patients with obstructive HC using cardiovascular magnetic resonance imaging. We investigated the relations between serum cTnI levels and clinical, echocardiographic, and cardiovascular magnetic resonance parameters and assessed the determinants of serum cTnI in 149 consecutive patients with obstructive HC. The median level of serum cTnI was 0.019 ng/ml (interquartile range 0.009 to 0.044). CTnI was elevated (≥0.04 ng/ml) in 42 (28%) of the overall cohort. Patients with elevated cTnI had greater maximum wall thickness (p <0.001), larger left ventricular mass index (LVMI, p <0.001), more frequency of left atrium diameter ≥50 mm (p = 0.020), higher plasma values of N-terminal pro-B-type natriuretic peptide (p <0.001), and less hypertension (p = 0.014). Serum cTnI levels were positively correlated with maximum wall thickness (r = 0.444, p <0.001), LVMI (r = 0.556, p <0.001), N-terminal pro-B-type natriuretic peptide (r = 0.305, p <0.001), left ventricular end-diastolic volume index (r = 0.246, p = 0.002), and left ventricular end-systolic volume index (r = 0.272, p = 0.001) but negatively with left ventricular ejection fraction (r = -0.180, p = 0.028). On multivariate analysis, LVMI was independently associated with both elevated cTnI (odds ratio 1.032, p = 0.001) and increasing serum cTnI levels (β = 0.556, p <0.001). In addition, the presence of hypertension was independently related to less likely elevated cTnI (odds ratio 0.307, p = 0.029) and decreasing levels of serum cTnI (β = -0.165, p = 0.015). In conclusion, levels of serum cTnI are elevated in a significant proportion of our patients. Serum cTnI is associated with multiple parameters of disease severity, suggesting its great significance in assessing cardiac remodeling in patients with obstructive HC. Left ventricular hypertrophy, as indicated by LVMI, is the major determinant of serum cTnI levels.