Correlation of electrocardiographic changes and myocardial fibrosis in patients with hypertrophic cardiomyopathy detected by cardiac magnetic resonance imaging

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.

Normal computerized Q wave measurements in healthy young athletes

BACKGROUND

Recent Expert consensus statements have sought to decrease false positive rates of electrocardiographic abnormalities requiring further evaluation when screening young athletes. These statements are largely based on traditional ECG patterns and have not considered computerized measurements.

OBJECTIVE

To define the normal limits for Q wave measurements from the digitally recorded ECGs of healthy young athletes.

METHODS

All athletes were categorized by sex and level of participation (high school, college, and professional), and underwent screening ECGs with routine pre-participation physicals, which were electronically captured and analyzed. Q wave amplitude, area and duration were recorded for athletes with Q wave amplitudes greater than 0.5mm at standard paper amplitude display (1mV/10mm). ANOVA analyses were performed to determine differences these parameters among all groups. A positive ECG was defined by our Stanford Computerized Criteria as exceeding the 99th percentile for Q wave area in 2 or more leads. Proportions testing was used to compare the Seattle Conference Q wave criteria with our data-driven criteria.

RESULTS

2073 athletes in total were screened. Significant differences in Q wave amplitude, duration and area were identified both by sex and level of participation. When applying our Stanford Computerized Criteria and the Seattle criteria to our cohort, two largely different groups of athletes are identified as having abnormal Q waves.

CONCLUSION

Computer analysis of athletes' ECGs should be included in future studies that have greater numbers, more diversity and adequate end points.

ECG-derived spatial QRS-T angle is strongly associated with hypertrophic cardiomyopathy

INTRODUCTION

ECG-derived vectorcardiography (VCG) has diagnostic and prognostic value in various diseases. Hypertrophic cardiomyopathy (HCM), a genetic disease with unexplained left ventricular hypertrophy, is one of the most common causes of sudden cardiac death (SCD) in young persons. Genotype positive status is associated with increased risk of systolic dysfunction, heart failure, and (SCD). Herein, we aimed to determine the diagnostic utility of derived VCG parameters in a large cohort of genotyped HCM patients.

METHODS

Between 1997 and 2007, genetic testing was performed on 1053 unrelated patients with HCM. Of these, 967 had 12-lead ECGs suitable for computerized derivation of VCG parameters, including the spatial mean and peaks QRS-T angles, spatial ventricular gradient (SVG), spatial QRS, QT, and Tpeak-Tend (TpTe) intervals. ECGs were also evaluated using Seattle ECG criteria. Differences between HCM patients and healthy controls as well as between genotype positive versus genotype negative HCM patients were assessed.

RESULTS

Spatial peaks (129.3±26.4 vs.30.5±24.2 degrees) and spatial mean QRS-T angles (121.8±38.6 vs. 47.3±27.6 degrees) were significantly higher in patients with HCM than in controls (P<0.001). The spatial peaks and mean QRS-T angles identified 94% and 84% of HCM patients, respectively, while Seattle criteria identified 70.7% of patients (P<0.001). Genotype positive patients had higher spatial mean QRS-T angles, spatial TpTe (P<0.001 respectively), spatial peaks QRS-T angles (P=0.017) and lower SVG (P<0.001) than genotype negative patients.

CONCLUSIONS

ECG-derived spatial QRS-T angles can differentiate patients with HCM from controls and could provide a better tool than traditional Seattle criteria. Clinical usefulness of VCG to differentiate genotype-negative from genotype-positive patients has yet to be established.

Clinical Characteristics and Prognosis of End-stage Hypertrophic Cardiomyopathy

Background:

End-stage hypertrophic cardiomyopathy (HCM) is complicated by substantial adverse events. However, few studies have focused on electrocardiographic features and their prognostic values in HCM. This study aimed to evaluate the clinical manifestations and prognostic value of electrocardiography in patients with end-stage HCM.

Methods:

End-stage HCM patients were enrolled from a total of 1844 consecutive HCM patients from April 2002 to November 2013 at Fuwai Hospital. Clinical data, including medical history, electrocardiography, and echocardiography, were analyzed. Cox hazards regression analysis was used to assess the risk factors for cardiovascular mortality.

Results:

End-stage HCM was identified in 99 (5.4%) patients, averaged at 52 ± 16 years old at entry. Atrial fibrillation was observed in 53 patients and mural thrombus in 19 patients. During 3.9 ± 3.0 years of follow-up, embolic stroke, refractory heart failure, and death or transplantation were observed in 20, 39, and 51 patients, respectively. The incidence of annual mortality was 13.2%. Multivariate Cox hazards regression analysis identified New York Heart Association Class (NYHA) III/IV at entry (hazard ratio [HR]: 1.99; 95% confidence interval [CI]: 1.05–3.80; P = 0.036), left bundle branch block (LBBB) (HR: 2.80; 95% CI: 1.47–5.31; P = 0.002), and an abnormal Q wave (HR: 2.21; 95% CI: 1.16–4.23; P = 0.016) as independent predictors of cardiovascular death, in accordance with all-cause death and heart failure-related death.

Conclusions:

LBBB and an abnormal Q wave are risk factors of cardiovascular mortality in end-stage HCM and provide new evidence for early intervention. Susceptibility of end-stage HCM patients to mural thrombus and embolic events warrants further attention.

Relationship between electrocardiographic findings and Cardiac Magnetic Resonance phenotypes in patients with Hypertrophic Cardiomyopathy

Background

Q waves and negative T waves are common electrocardiographic (ECG) abnormalities in patients with Hypertrophic Cardiomyopathy (HCM). Several studies correlated ECG findings with presence and extent of fibrosis and hypertrophy; however, their significance remains incompletely clarified. Our study aimed to explain the mechanism behind Q and negative T waves by comparing their positions on a 12-lead ECG with phenotypes observed at Late Gadolinium Enhancement (LGE) Cardiac Magnetic Resonance (CMR).

Methods

12-lead ECG and LGE-CMR were performed in 88 consecutive patients with HCM (42 SD 16 years, 65 males). Using Delta Thickness ratio (DT ratio), and “global” and “parietal” LGE at CMR, the extent and distribution of myocardial hypertrophy and fibrosis were studied in correlation with ECG abnormalities.

Results

Q waves in different leads were not associated with “parietal” LGE score. Lateral Q waves correlated with an increased DT ratio Inferior Septum/Lateral wall (p = 0.01). A similar correlation between inferior Q waves and an increased DT Ratio Anterior wall/Inferior wall was of borderline statistical significance (p = 0.06). As expected, ECG signs of LV hypertrophy related to a raised Left Ventricular Mass Index (LVMI) (p < 0.0001) and mean wall thickness (p = 0.01). Depolarization disturbances, including negative T waves in lateral (p = 0.044) and anterior (p = 0.031) leads correlated with “parietal” LGE scores while QT dispersion (p = 0.0001) was associated with “global” LGE score.

Conclusion

In HCM patients, Q waves are generated by asymmetric hypertrophy rather than by myocardial fibrosis, while negative T waves result from local LGE distribution at CMR.

Sensibilidade e especificidade do exame eletrocardiográfico na detecção de sobrecargas atriais e/ou ventriculares em gatos da raça Persa com cardiomiopatia hipertrófica

Resumo: A cardiomiopatia hipertrófica (CMH) é a principal cardiopatia dos felinos e é caracterizada por hipertrofia miocárdica concêntrica, sem dilatação ventricular. O ecocardiograma é o melhor meio diagnóstico não invasivo para a diferenciação das cardiomiopatias e é considerado padrão ouro para a detecção de hipertrofia ventricular presente na CMH. Alterações eletrocardiográficas também são comuns em animais com CMH e o eletrocardiograma (ECG) é um teste de triagem para detecção de hipertrofia ventricular em humanos, sendo um exame rápido e facilmente disponível. Em gatos, poucos estudos foram realizados quanto à sensibilidade e especificidade do ECG na detecção de hipertrofia ventricular. Com a intenção de avaliar o uso do ECG como ferramenta de triagem para diagnóstico de CMH em felinos, gatos da raça Persa (n=82) foram avaliados por meio de exames ecocardiográfico e eletrocardiográfico. Animais com bloqueios e/ou distúrbios de condução foram excluídos da análise estatística (n=22). Posteriormente, os animais incluídos foram classificados em: normais (n=38), suspeitos (n=6) e acometidos pela CMH (n=16). Observaram-se diferenças estatísticas na amplitude da onda P em DII e na amplitude de onda R em DII, CV6LL e CV6LU, com valores maiores nos animais com CMH; e nos valores ecocardiográficos de velocidade e gradiente de pressão do fluxo aórtico, diâmetro do átrio esquerdo (AE) e relação AE/Ao, com valores maiores nos gatos com CMH. Dentre os animais com alterações eletrocardiográficas sugestivas de sobrecarga atrial esquerda (n=7), apenas dois realmente apresentavam aumento do AE no ecocardiograma; e dentre os animais com aumento atrial esquerdo ao ecocardiograma (n=7), apenas dois apresentavam alterações eletrocardiográficas sugestivas de sobrecarga do AE (sensibilidade de 40,40% e especificidade de 90,90%). Dentre os gatos com alterações eletrocardiográficas sugestivas de sobrecarga ventricular esquerda (n=6), cinco realmente apresentavam hipertrofia ventricular ao ecocardiograma; e dentre os animais com CMH ao ecocardiograma (n=16), apenas cinco apresentaram alterações eletrocardiográficas sugestivas de sobrecarga do VE (sensibilidade de 31,25% e especificidade de 97,72%). Observou-se correlação positiva entre espessura diastólica do septo interventricular e/ou da parede livre do ventrículo esquerdo e a amplitude da onda R em derivações DII e CV6LU. O eletrocardiograma é um exame rápido e de fácil execução, apresenta boa especificidade na detecção de hipertrofia ventricular em felinos, porém, possui baixa sensibilidade, com grande número de falsos negativos. Desta forma, o ECG auxilia no diagnóstico, mas não substitui o ecocardiograma na confirmação da hipertrofia ventricular.

Increased Transforming Growth Factor-β Levels Associated With Cardiac Adverse Events in Hypertrophic Cardiomyopathy

BACKGROUND

Hypertrophic cardiomyopathy (HCM) is a common genetic heart disease characterized by ventricular hypertrophy, myocardial fibrosis, and impaired ventricular relaxation. The exact mechanisms by which fibrosis is caused remain unknown.

HYPOTHESIS

Circulating TGF-β is related to poor prognosis in HCM.

METHODS

We compared TGF-β levels of 49 HCM patients with those of 40 non-HCM patients. We followed the patients with HCM for 18 months and divided them into 2 groups: low TGF-β (≤ 4877 pg/mL) and high TGF-β (> 4877 pg/mL). We compared the 2 groups in terms of brain natriuretic peptide (BNP), echocardiographic parameters, and clinical outcomes including myocardial infarction, arrhythmias, implantable cardioverter-defibrillator implantation, hospitalization, New York Heart Association (NYHA) class, acute heart failure, and mortality.

RESULTS

The HCM patients had higher TGF-β levels than those in the control group (P = 0.005). In the follow-up, those in the high TGF-β group had higher BNP levels, larger left-atrial size, thicker interventricular septum, NYHA class, more hospitalizations, and a greater number of clinical adverse events (P < 0.001, P = 0.01, P < 0.001, P = 0.002, P < 0.001 and P = 0.003, respectively). TGF-β level of > 4877 pg/mL can predict adverse events with a specificity of 75% and a sensitivity of 72% (P = 0.014). In multivariate regression analysis, TGF-β, BNP, and interventricular septum thickness were significantly associated with adverse events (P = 0.028, P = 0.030, and P = 0.034, respectively).

CONCLUSIONS

The TGF-β level is higher in HCM patients and associated with a poor prognosis in HCM.

Hypertrophic cardiomyopathy: Can the noninvasive diagnostic testing identify high risk patients?

Hypertrophic cardiomyopathy (HCM) is the most common cause of sudden cardiac death (SCD) in the young, particularly among athletes. Identifying high risk individuals is very important for SCD prevention. The purpose of this review is to stress that noninvasive diagnostic testing is important for risk assessment. Extreme left ventricular hypertrophy and documented ventricular tachycardia and fibrillation increase the risk of SCD. Fragmented QRS and T wave inversion in multiple leads are more common in high risk patients. Cardiac magnetic resonance imaging provides complete visualization of the left ventricular chamber, allowing precise localization of the distribution of hypertrophy and measurement of wall thickness and cardiac mass. Moreover, with late gadolinium enhancement, patchy myocardial fibrosis within the area of hypertrophy can be detected, which is also helpful in risk stratification. Genetic testing is encouraged in all cases, especially in those with a family history of HCM and SCD.

Impact of adverse left ventricular remodeling on sudden cardiac death in patients with hypertrophic cardiomyopathy

BACKGROUND

Adverse left ventricular (LV) remodeling predicts heart failure symptoms and overt LV dysfunction in patients with hypertrophic cardiomyopathy (HCM), but its influence on the occurrence of sudden cardiac death (SCD) is unknown. The aim of this study was to investigate the effect of adverse LV remodeling on SCD risk in patients with HCM.

HYPOTHESIS

Adverse LV remodeling increases SCD in HCM patients.

METHODS

This study included 41 patients with HCM who experienced SCD; each case was matched with 3 controls based on age, gender, and time of first contact. In this population of 164 patients, predictors of SCD were identified using univariable and multivariable logistic regression and expressed as odds ratio (OR) with 95% confidence interval (CI).

RESULTS

Baseline characteristics, such as New York Heart Association (NYHA) class, systolic and diastolic left ventricular function, left ventricular wall thickness, left atrial size, atrial fibrillation, and established risk factors for SCD were similar in cases and controls. Independent predictors of SCD during follow-up (median follow-up, 7.7 ± 6.5 years) were: increase in NYHA class (OR: 8.7 [95% CI: 2.5-30.5], P = 0.001), decrease of fractional shortening (per % decrease, OR: 1.09 [95% CI: 1.03-1.14], P = 0.001), and decrease of diastolic function (OR: 3.5 [95% CI: 1.2-10.2], P = 0.02).

CONCLUSIONS

This study shows that SCD risk in HCM increases when adverse remodeling occurs. Because cases and controls were similar at baseline, these findings emphasize the importance of vigilant follow-up of HCM patients and could aid clinical decision making concerning implantable cardioverter-defibrillator implantation, especially in patients with moderate risk for SCD.

QRS widening rates and genetic polymorphisms of matrix metalloproteinases in a cohort of patients with chronic heart failure

BACKGROUND

QRS duration is considered to be an indicator of adverse outcome in patients with heart failure (HF), and genetic polymorphisms may be involved in this conductivity impairment. We studied the prognostic impact of the QRS widening rate (QRS-WR) on patients with HF and the influence of the matrix metalloproteinases gene polymorphisms on the QRS-WR.

METHODS

This prospective cohort study included 184 patients with left ventricular (LV) systolic dysfunction (LV ejection fraction [LVEF] < 45%). The QRS-WR was calculated as the difference between 2 electrocardiogram assessments (in ms) divided by the time elapsed between each evaluation (months). The MMP-1 -1607 1G/2G, MMP-2 -790G/T and -1575G/A, MMP-3 -1171 5A/6A, MMP-9 -1562 C/T and R279Q, and MMP-12 -82A/G polymorphisms were genotyped using polymerase chain reaction-restriction fragment length polymorphism.

RESULTS

Patients were predominantly white (68%) men (67%) in New York Heart Association functional classes I and II (77%). Patients with HF with a QRS-WR ≥ 0.5 ms/month had more HF-related deaths and more combined clinical events than those with a QRS-WR < 0.5 ms/month (P = 0.03 and P = 0.01, respectively). After adjusting for other covariates, the QRS-WR remained an independent predictor of combined clinical events (hazard ratio, 1.6; 95% confidence interval, 1.1-2.5; P = 0.02). The MMP-1 2G2G genotype was associated with nearly a 2-fold increase in QRS-WR (P = 0.03). Conversely, patients with the MMP-3 5A5A genotype and a nonischemic cause of HF were protected against QRS enlargement (P = 0.03).

CONCLUSIONS

QRS-WR retains prognostic value in patients with chronic HF receiving guideline-based pharmacologic treatment. MMP gene polymorphisms can influence the rate of QRS enlargement over time.