Increased left ventricular dimensions in patients with frequent nonsustained ventricular arrhythmia and no evidence of underlying heart disease

Correlations between cardiac troponin I and nonsustained ventricular tachycardia in hypertrophic obstructive cardiomyopathy

BACKGROUND

Nonsustained ventricular tachycardia (NSVT) is an independent risk factor for sudden cardiac death (SCD) in patients with hypertrophic obstructive cardiomyopathy (HOCM). However, data concerning the correlations of cardiac biomarkers and NSVT in HOCM are rather limited.

HYPOTHESIS

Our study aimed to investigate the associations between the occurrence of NSVT and circulating biomarkers representing myocardial injury (cardiac troponin I, cTnI), cardiac function (N-terminal pro-brain natriuretic peptide, NT-pro BNP), and inflammation (high-sensitivity C-reactive protein) in a large Chinese HOCM cohort.

METHODS

A total of 755 consecutive HOCM patients were recruited. Systematic cardiac evaluations and circulating biomarkers were examined routinely in all subjects under the clinically stable status. According to the results of 24-hour Holter monitoring, patients were divided into the NSVT group (n = 138) and the nonventricular tachycardia (non-VT) group (n = 617).

RESULTS

Compared with the non-VT group, circulating levels of both cTnI and NT-pro BNP elevated significantly in patients with positive NSVT episodes (P < .001). Multivariable analyses demonstrated that cTnI was independently associated with the presence of NSVT (OR = 1.675, 95% CI: 1.406-1.994, P < .001). Concentrations of cTnI increased progressively not only with the aggravation of ventricular arrhythmic events (P < .001), but also with the growing risk of SCD in HOCM patients (P < .001). Serum cTnI ≥ 0.0265 ng/mL indicated predictive value for the occurrence of NSVT in the HOCM cohort (area under the curve = 0.707, 95% CI: 0.660-0.754, P < .001).

CONCLUSIONS

Elevated cTnI was an independent determinant of NSVT, and it seemed to be valuable for assessing the clinical status of ventricular arrhythmias and the risk of SCD in patients with HOCM.

Premature ventricular contraction-induced cardiomyopathy: an emerging entity

INTRODUCTION

Over the past 10-15 years, there has been an increasing amount of evidence that frequent premature ventricular contractions (PVCs) are associated with the development of a reversible cardiomyopathy. Areas covered: This review considers current evidence of the association between PVCs and the development of cardiomyopathy, risk factors, and available treatment modalities based on available published literature. Expert commentary: The field is rapidly evolving, although evidence is based primarily on observational studies. Pharmacological therapy may suppress PVCs and lead to resolution of cardiomyopathy in many patients. In addition, catheter ablation has emerged as an effective treatment modality that has compared favorably to pharmacological antiarrhythmic therapy. The excellent outcome in successfully treated patients should prompt physicians to consider whether frequent PVCs may be a contributing factor in patients with heart failure.

Radiofrequency ablation can reverse the structural remodeling caused by frequent premature ventricular contractions originating from the right ventricular outflow tract even in a "normal heart"

OBJECTIVE

The aim of this study was to evaluate whether frequent premature ventricular contractions originating from the right ventricular outflow tract remodel the cardiac structure and function in patients with a "seemingly normal heart" and whether radiofrequency ablation can reverse this remodeling.

METHODS

Sixty-eight patients with idiopathic frequent premature ventricular contractions originating from the right ventricular outflow tract and normal heart structure and function were enrolled in this study. The patients were divided into three groups according to the therapeutic method: radiofrequency ablation group (24 cases), anti-arrhythmia drug group (26 cases), and control group (18 cases without any treatment). Clinical Registration number: ChiCTR-ONRC-12002834 RESULTS: The basic patient characteristics were comparable between the three groups, except for the premature ventricular contraction rate, which was significantly lower in the control group. After six months of follow up, the premature ventricular contraction rate was significantly reduced in the radiofrequency ablation group, which was accompanied by a significant decrease in the following cardiac cavity inner diameters, as determined by echocardiography: right atrium (33.33±3.78 vs. 30.05±2.60 mm, p = 0.001), right ventricle (23.24±2.40 vs. 21.05±2.16 mm, p = 0.020), and left ventricle (44.76±4.33 vs. 41.71±3.44 mm, p = 0.025). These results were similar in the anti-arrhythmia drug group, although this group exhibited a smaller extent of change (right atrium: 33.94±3.25 vs. 31.27±3.11 mm, p = 0.024; right ventricle: 22.97±3.09 vs. 21.64±2.33 mm, p = 0.049; left ventricle: 45.92±6.38 vs. 43.84±5.67 mm, p = 0.039), but not in the control group (p>0.05). There was a tendency toward improvement in the cardiac functions in both the radiofrequency ablation and anti-arrhythmia drug groups. However, these differences were not statistically significant (p>0.05).

CONCLUSIONS

These results indicate that radiofrequency ablation can potentially reverse the cardiac remodeling caused by frequent premature ventricular contractions even in structurally normal hearts and that frequent premature ventricular contractions should be abated even in structurally normal hearts.

N-terminal prohormone brain natriuretic peptide-proBNP levels in ventricular arrhythmias in children

BACKGROUND

Ventricular arrhythmias are the most common consequences of structural and functional heart diseases, but cases with no evident pathology are also observed. A parameter indicating asymptomatic circulatory failure could support decisions related to possible treatment of ventricular arrhythmias.

HYPOTHESIS

The study objective was the evaluation of N-terminal prohormone brain natriuretic peptide (NT-proBNP) levels in children with ventricular arrhythmias and an attempt to determine if this parameter may be used for diagnosis and prognosis of ventricular arrhythmias.

MATERIAL AND METHODS

The study population was comprised of 36 children age 5 to 17.5 years old with idiopathic ventricular arrhythmias (Group B) graded mild or potentially malignant; 29 patients with mild ventricular arrhythmias were included into Group B1; and 7 patients with potentially malignant cases into Group B2. In all the patients, NT-proBNP assays were performed.

RESULTS

The NT-proBNP levels in Groups B, B1, B2 and the control group (Group K) were as follows: 41.5 +/- 15.1 pg/mL, 35.5 +/- 18.5 pg/mL, 66.3 +/- 24.9 pg/mL and 31.5 +/- 15.1 pg/mL, respectively. Between the groups with and without arrhythmias (Group B vs Group K), no statistically significant differences in NT-proBNP levels were found. However, markedly higher NT-proBNP levels were shown in the children with potentially malignant arrhythmias (Group B2) compared to the patients with mild arrhythmias (B1) and the control group (Group K).

CONCLUSIONS

The level of NT-proBNP increases with the severity of ventricular arrhythmia. NT-proBNP assays can be helpful for diagnosing and grading the severity of ventricular arrhythmias.

Cardiac troponin I and ventricular arrhythmia in patients with chronic heart failure

BACKGROUND

Both detectable serum cardiac troponin I (cTnI) and ventricular dysrhythmias are common in patients with chronic heart failure (CHF) and are paralleled with the severity of the CHF. However, the relationship between serum cTnI and ventricular arrhythmia severity in patients with CHF remains unknown; the mechanism of the ventricular arrhythmia in the CHF patients also remains unclear.

MATERIALS AND METHODS

The study group included 218 patients with CHF who had cTnI assay drawn at the time of initial presentation. Patients with acute myocardial infarction or myocarditis were excluded from the analysis. The patients were divided into two groups: cTnI-positive with serum cTnI > 0.5 ng mL(-1) (n = 98) and cTnI-negative with serum cTnI < or = 0.5 ng mL(-1) (n = 120). The severity of ventricular dysrhythmias was assessed by 24-h Holter monitoring, using prospectively defined measures of ventricular arrhythmic burden.

RESULTS

Prevalence of risk factors for ventricular dysrhythmias was equal in both groups. All measures of ventricular ectopy were much higher in patients of the cTnI-positive groups. Mean hourly ventricular pairs (13.59 +/- 10.3 vs. 11.1 +/- 6.01, P = 0.027), mean hourly repetitive ventricular beats (26.01 +/- 13.67 vs. 22.01 +/- 13.56, P = 0.032), and the frequency of ventricular tachycardia episodes per 24 h (12.54 +/- 16.68 vs. 7.68 +/- 11.54, P = 0.012) were higher in patients with detectable cTnI levels. After inclusion of clinical variables and drug therapies in a multivariate analysis, the positive relationship between cTnI and the frequency of ventricular pairs (P = 0.03), repetitive ventricular beats (P = 0.037), and ventricular tachycardia (P = 0.03) remained independent. In multivariate logistic regression, the risk of developing ventricular tachycardia was higher in patients with detectable cTnI levels with an adjusted odds ratio (OR) of 2.31 (95% CI, 1.22-2.65, P = 0.003).

CONCLUSIONS

In patients with CHF, serum cTnI is closely related to increased occurrence of ventricular dysrhythmias and could identify a subgroup of patients with ventricular tachycardia. The minimal myocardial injury detected by serum cTnI might be the abnormal substrate for ventricular dysrhythmias.

The influence of premature ventricular contractions on left ventricular function in asymptomatic children without structural heart disease: an echocardiographic evaluation

BACKGROUND

Isolated monomorphic premature ventricular contractions (PVCs) are not uncommon in the pediatric population. The degree of cardiac dysfunction caused by PVCs in children without structural heart disease is unknown.

PURPOSE

To investigate the influence of PVCs on echocardiographic left ventricular (LV) systolic function in children without structural heart disease.

METHODS

Forty asymptomatic children with isolated monomorphic PVCs without structural heart disease were selected. The median age was 6 years, range of 3-12 years. The following subgroups were compared: frequent vs. infrequent PVCs (> or < or = 10/min); short vs. long coupling interval (RR'/RR ratio < or = or > 0.6); and short vs. long QT interval (QT < or = or > 400 ms). Using echocardiography the left ventricular ejection fraction (LVEF in percentage) and cardiac index (CI in L/min/m2) were measured for both normal sinus beats (SB-LVEF and CI), PVCs (PVC-LVEF and CI) and the average LVEF and CI were calculated. All values were expressed as means +/- SD.

RESULTS

In all children LV dimensions and the SB-LVEF and CI were within normal limits. The PVC-LVEF (48 +/- 5) and PVC-CI (1.57 +/- 0.19) were significantly decreased and the average CI was 2.41 +/- 0.29. In 27 pts with > 10 PVCs/min the average LVEF and CI decreased to 53 +/- 5 and 2.08 +/- 0.24 respectively. In 16 pts with PVCs and a short coupling interval (RR'/RR < or = 0.6) the PVC-LVEF and PVC-CI was 43 +/- 0.03 and 1.50 +/- 0.14, which was significantly lower than in 24 pts with a long coupling interval (58 +/- 4, 1.88 +/- 0.11). In 11 pts with a prolonged QT interval (> 400 ms) the PVC-LVEF and PVC-CI was significantly lower than in the 29 children with a shorter QT interval, 41 +/- 5 vs. 55 +/- 4 and 1.46 +/- 0.13 vs. 1.86 +/- 0.15 respectively (all p < 0.01).

CONCLUSION

In asymptomatic children with isolated monomorphic PVCs the average ejection fraction and cardiac output is markedly reduced if PVCs are frequent (> 10/min), have a short coupling interval or a prolonged QT interval.

Relationship Between Brain Natriuretic Peptide, Myocardial Wall Stress, and Ventricular Arrhythmia Severity

We previously demonstrated that the severity of arrhythmias is reflected by circulating brain natriuretic peptide (BNP) concentrations in patients without signs of congestive heart failure. In the present study, we evaluated the relationships between the severity of the arrhythmia, BNP concentration, and echocardiographic findings. The subjects consisted of 52 patients with ventricular premature contractions (VPC) but no manifestations of heart failure and no digoxin or beta-blocker therapy. Patients underwent Holter monitoring, plasma sampling for BNP measurement, and transthoracic echocardiography (TTE). We scored the motion of 16 left ventricular segments, deriving a wall-motion score index (WMSI) by totaling the scores and dividing by the number of segments scored. Twenty-three patients with Lown grade I to II arrhythmias constituted group A while group B consisted of 29 Lown III to IV patients. Group B had BNP concentrations triple those in group A (57.2 versus 18.1 pg/mL, P < 0.01). Left ventricular ejection fraction (LVEF) was similar in groups A and B (65.2% versus 62.1%, NS). Although left ventricular end-diastolic dimension (LVEDD) was normal in both groups, group B exhibited a larger LVEDD than group A (50 versus 46 mm, P < 0.005). The correlation (r) between BNP and interventricular septum thickness (IVST) was 0.27 (P = 0.013) in group A and 0.37 (P < 0.0001) in group B. Between BNP and posterior wall thickness (PWT), the correlation was 0.23 (P = 0.014) in group A versus 0.33 (P < 0.0001) in group B. The WMSI in group B was higher than in group A (1.34 versus 1.11, P < 0.05). We believe that besides the changes in echocardiographic parameters, the BNP elevation in group B could be a response to abnormal wall stress from the severe ventricular arrhythmias.

Left ventricular diastolic dysfunction induced by cyclophosphamide in blood stem cell transplantation

Cardiac complications are major limiting factors regarding the success of high-dose chemotherapy supported by blood stem cell transplantation (BSCT). The cardiotoxicity of cyclophosphamide remains obscure relative to that of anthracyclines. The aim of this study was to estimate noninvasively the cardiotoxicity of cyclophosphamide administered during the pretransplant conditioning of BSCT for patients with various hematological diseases. A total of 27 consecutive patients were divided into two groups depending on the conditioning regimen, ie, group A (n=15) which received cyclophosphamide (median dose of 120 mg/kg; range 100 to 200 mg/kg) and group B (n=12) which did not. Ultrasound cardiograms (UCG) and signal-averaged electrocardiograms (SAECG) were recorded in the two groups both preceding and following the BSCT. There were no statistical intergroup or intragroup differences in left ventricular (LV) dimensions or contractile function. Significant (P<0.01) posttransplant increases in interventricular septal wall thickness and Ap/Ep ratio were noted in group A. Moreover, the filtered QRS duration as estimated by SAECG was prolonged (P<0.05) whereas the summated LV voltage (S(V1)+R(V5)) was reduced in the posttransplant period only in group A. These results suggest that early cyclophosphamide cardiotoxicity was characterized by LV diastolic rather than systolic dysfunction. These findings may contribute to acute hemodynamic deterioration observed after cyclophosphamide-containing conditioning chemotherapy.

Markers of electrical instability in hypertensive patients with and without ventricular arrhythmias. Are they useful in identifying patients with different risk profiles?

BACKGROUND

Markers of electrical instability of the ventricular myocardium, namely abnormal repolarization and late potentials, are frequently observed in patients with hypertension when both ventricular arrhythmias and left ventricular hypertrophy are present. This information cannot be extrapolated to the population of hypertensive patients with ventricular arrhythmias but without left ventricular hypertrophy.

OBJECTIVE

To evaluate QT duration, QT dispersion and the incidence of ventricular late potentials in patients with essential hypertension, already on anti-hypertensive therapy, both with and without non-sustained ventricular arrhythmia.

DESIGN

The study population consisted of 49 patients with essential hypertension who were compared to 89 control normotensive subjects both with and without frequent (> 30 per h) ventricular ectopic beats (VPBs). Patients were divided into four groups: (1) hypertensive patients without VPBs (H, n = 19), (2) hypertensive patients with VPBs (HA, n = 30), (3) normotensive subjects without VPBs (C, n = 28), and (4) normotensive subjects with VPBs (CA, n=61).

METHODS

Echocardiographic parameters, QT interval, QT dispersion and signal-averaged ECG were evaluated without withdrawing anti-hypertensive drugs.

RESULTS

In no case was left ventricular hypertrophy documented. The number of VPBs during 24 h Holter recording (median 11 343 versus 7617) and the incidence of repetitive VPBs (37 versus 46% of patients) were similar in the two groups of patients (HA versus CA). Signal-averaged ECG parameters were normal and not different between the four groups. QT interval was longer in hypertensive patients compared to controls irrespective of the presence of VPBs. QT dispersion was slightly greater in subjects with VPBs, both hypertensive and normotensive, compared to subjects without arrhythmias.

CONCLUSIONS

In patients with hypertension well-controlled by drug therapy and without left ventricular hypertrophy, frequent VPBs are not associated with markers indicating an electrophysiological substrate for re-entrant arrhythmias. However, QT prolongation suggests the persistence of a higher risk of cardiovascular mortality that is independent of the presence of VPBs.