Characteristics of the increase in plasma brain natriuretic peptide level in left ventricular systolic dysfunction, associated with muscular dystrophy in comparison with idiopathic dilated cardiomyopathy

Efficacy of exon-skipping therapy for DMD cardiomyopathy with mutations in actin binding domain 1

Exon-skipping therapy is a promising treatment strategy for Duchenne muscular dystrophy (DMD), which is caused by loss-of-function mutations in the DMD gene encoding dystrophin, leading to progressive cardiomyopathy. In-frame deletion of exons 3-9 (Δ3-9), manifesting a very mild clinical phenotype, is a potential targeted reading frame for exon-skipping by targeting actin-binding domain 1 (ABD1); however, the efficacy of this approach for DMD cardiomyopathy remains uncertain. In this study, we compared three isogenic human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) expressing Δ3-9, frameshifting Δ3-7, or intact DMD. RNA sequencing revealed a resemblance in the expression patterns of mechano-transduction-related genes between Δ3-9 and wild-type samples. Furthermore, we observed similar electrophysiological properties between Δ3-9 and wild-type hiPSC-CMs; Δ3-7 hiPSC-CMs showed electrophysiological alterations with accelerated CaMKII activation. Consistently, Δ3-9 hiPSC-CMs expressed substantial internally truncated dystrophin protein, resulting in maintaining F-actin binding and desmin retention. Antisense oligonucleotides targeting exon 8 efficiently induced skipping exons 8-9 to restore functional dystrophin and electrophysiological parameters in Δ3-7 hiPSC-CMs, bringing the cell characteristics closer to those of Δ3-9 hiPSC-CMs. Collectively, exon-skipping targeting ABD1 to convert the reading frame to Δ3-9 may become a promising therapy for DMD cardiomyopathy.

Cardiovascular Measures of All-Cause Mortality in Duchenne Muscular Dystrophy

BACKGROUND

Cardiopulmonary failure is the leading cause of death in Duchenne muscular dystrophy (DMD). Research into DMD-specific cardiovascular therapies is ongoing, but there are no Food and Drug Administration-approved cardiac end points. To adequately power a therapeutic trial, appropriate end points must be chosen and the rate of change for these end points reported. The objective of this study was to evaluate rate of change for cardiac magnetic resonance and blood biomarkers and to determine which measures associate with all-cause mortality in DMD.

METHODS

Seventy-eight DMD subjects underwent 211 cardiac magnetic resonance studies analyzed for left ventricular (LV) ejection fraction, indexed LV end diastolic and systolic volumes, circumferential strain, late gadolinium enhancement presence and severity (global severity score, and full width half maximum), native T1 mapping, T2 mapping, and extracellular volume. Blood samples were analyzed for BNP (brain natriuretic peptide), NT-proBNP (N-terminal pro-B-type natriuretic peptide), and troponin I. Cox proportional hazard regression modeling was performed with all-cause mortality as the outcome.

RESULTS

Fifteen subjects (19%) died. LV ejection fraction, indexed end systolic volumes, global severity score, and full width half maximum worsened at 1 and 2 years while circumferential strain and indexed LV end diastolic volumes worsened at 2 years. LV ejection fraction, indexed LV end diastolic and systolic volumes, late gadolinium enhancement full width half maximum, and circumferential strain associated with all-cause mortality (P<0.05). NT-proBNP was the only blood biomarker that associated with all-cause mortality (P<0.05).

CONCLUSIONS

LV ejection fraction, indexed LV volumes, circumferential strain, late gadolinium enhancement full width half maximum, and NT-proBNP are associated with all-cause mortality in DMD and may be the best end points for use in cardiovascular therapeutic trials. We also report change over time of cardiac magnetic resonance and blood biomarkers.

Duchenne muscular dystrophy patients: troponin leak in asymptomatic and implications for drug toxicity studies

BACKGROUND

Cardiomyopathy is the leading cause of death in Duchenne muscular dystrophy (DMD), but studies suggest heart failure biomarkers correlate poorly with cardiomyopathy severity. DMD clinical trials have used troponin I (cTnI) as a biomarker of toxicity, but it is unclear if asymptomatic DMD patients have elevated cTnI. We longitudinally evaluated cTnI, brain natriuretic peptide (BNP), and N-terminal pro-BNP (NT-proBNP) in a DMD cohort.

METHODS

DMD patients were prospectively enrolled and followed for 3 years. Serum was drawn at the time of cardiac magnetic resonance (CMR). Normal biomarker values were derived from healthy subjects. Biomarkers were correlated with CMR markers.

RESULTS

All subjects were asymptomatic at the time of enrollment. Several DMD subjects had transiently elevated cTnI. Those with elevated cTnI were more likely to have late gadolinium enhancement on baseline CMR. NT-proBNP correlated with indexed left ventricular end diastolic and maximum left atrial volumes. Otherwise, standard cardiac biomarkers did not correlate with CMR markers of cardiomyopathy.

CONCLUSIONS

CTnI, BNP, and NT-proBNP do not correlate with CMR assessment of cardiomyopathy progression. A subset of DMD patients have asymptomatic cTnI leak of uncertain clinical significance, though of critical importance if cTnI is used to assess for cardiac toxicity in future drug trials.

IMPACT

Asymptomatic patients with Duchenne muscular dystrophy (DMD) exhibit transient troponin I leak. NT-proBNP correlated with indexed left ventricular end diastolic volume and indexed maximum left atrial volume. Other cardiac biomarkers did not correlate with cardiac magnetic resonance (CMR) markers of cardiomyopathy.

The association between cardiac involvement and long-term clinical outcomes in patients with Duchenne muscular dystrophy

Aims

Despite advances in contemporary cardiopulmonary therapies, cardiomyopathy remains the leading cause of death in patients with Duchenne muscular dystrophy (DMD). Also, the long‐term clinical outcomes of patients with DMD and cardiomyopathy is unknown. This study investigated long‐term clinical outcomes and their associated factors in patients with late‐stage DMD.

Methods and results

A total of 116 patients with late‐stage DMD (age > 15 years) were enrolled in this retrospective study. All enrolled patients were followed up at a single tertiary referral hospital. LV systolic dysfunction was dichotomously defined as reduced [left ventricular ejection fraction (LVEF) ≤ 40%] vs. preserved [>40%] based on the initial echocardiographic result. The primary endpoint was all‐cause death. The secondary endpoint was a composite event defined as death or unexpected hospitalization due to cardiovascular reasons including chest pain, dyspnoea, and generalized oedema. The patients were divided into preserved (n = 84, 72.4%) and reduced LVEF groups (n = 32, 27.6%). The mean age was 20.8 ± 5.9 years, the mean disease duration, 8.8 ± 3.7 years, and the mean follow‐up duration, 1708 ± 659 days. For primary endpoint, the reduced LVEF group showed a lower rate of overall survival (Reduced LVEF vs. Preserved LVEF; 81.3% vs. 98.8%, log‐rank P = 0.005). In the multivariable Cox regression analysis, brain‐natriuretic peptide (BNP) level (adjusted hazard ratio [HR] 1.088, 95% confidence interval [CI] 1.019–1.162, P = 0.011) and diuretic use (adjusted HR 9.279, 95%CI 1.651–52.148, P = 0.011) were significant predictors of all‐cause death in patients with DMD. For the secondary endpoint, the reduced LVEF group had a lower rate of freedom from composite events than the preserved LVEF group (65.6% vs. 86.9%, log‐rank P = 0.005). In the multivariable Cox regression analysis, BNP level (adjusted HR 1.057, 95%CI 1.005–1.112, P = 0.032) and diuretic use (adjusted HR 4.189, 95% CI 1.704–10.296, P = 0.002) were significant predictors of the composite event in patients with DMD.

Conclusions

Patients with DMD and reduced LVEF had worse clinical outcomes than those with preserved LVEF. BNP level and diuretic use were associated with adverse clinical outcomes in patients with late‐stage DMD, irrespective of LVEF.

Tranilast for advanced heart failure in patients with muscular dystrophy: a single-arm, open-label, multicenter study

Background

The transient receptor potential cation channel subfamily V member 2 (TRPV2) is a stretch-sensitive calcium channel. TRPV2 overexpression in the sarcolemma of skeletal and cardiac myocytes causes calcium influx into the cytoplasm, which triggers myocyte degeneration. In animal models of cardiomyopathy and muscular dystrophy (MD), TRPV2 inhibition was effective against heart failure and motor function. Our previous pilot study showed that tranilast, a TRPV2 inhibitor, reduced brain natriuretic peptide (BNP) levels in two MD patients with advanced heart failure. Thus, this single-arm, open-label, multicenter study aimed to evaluate the safety and efficacy of tranilast for heart failure.

Methods

The study enrolled MD patients with advanced heart failure whose serum BNP levels were > 100 pg/mL despite receiving standard cardioprotective therapy. Tranilast was administered orally at 100 mg, thrice daily. The primary endpoint was the change in log (BNP) (Δlog [BNP]) at 6 months from baseline. The null hypothesis was determined based on a previous multicenter study of carvedilol results in a mean population Δlog (BNP) of 0.18. TRPV2 expression on peripheral blood mononuclear cell surface, cardiac events, total mortality, left ventricular fractional shortening, human atrial natriuretic peptide, cardiac troponin T, and creatine kinase, and pinch strength were also assessed.

Results

Because of the poor general condition of many patients, only 18 of 34 patients were included and 13 patients could be treated according to the protocol throughout the 6-month period. However, there were no serious adverse events related to tranilast except diarrhea, a known adverse effect, and the drug was administered safely. TRPV2 expression on the mononuclear cell surface was elevated at baseline and reduced after treatment. Cardiac biomarkers such as BNP, human atrial natriuretic peptide, and fractional shortening remained stable, suggesting a protective effect against the progression of heart failure. In the per protocol set group, Δlog [BNP] was − 0.2 and significantly lower than that in the null hypothesis.

Conclusions

Tranilast is safe and effective in inhibiting TRPV2 expression, even in MD patients with advanced heart failure. Further trials are needed to evaluate the efficacy of tranilast in preventing myocardial damage, heart failure, motor impairment, and respiratory failure.

Clinical trial registration The study was registered in the UMIN Clinical Trials Registry (UMIN-CTR: UMIN000031965, URL: http://www.umin.ac.jp/ctr/) [March 30, 2018] and the Japan Registry of Clinical Trials (jRCT, registration number: jRCTs031180038, URL: https://jrct.niph.go.jp/) [November 12, 2021]. Patient registration was started in December 19, 2018.

Study Protocol for a Multicenter, Open-Label, Single-Arm Study of Tranilast for Cardiomyopathy of Muscular Dystrophy

Duchenne (DMD) and other forms of muscular dystrophy (MD) are collectively rare and affect approx imately 20 per 100,000 people. The on-going development of exon skipping and other novel therapies for DMD is expected to lead to improvements in motor function prognosis. However, improvements in motor dysfunction with these novel therapies are associated with the risk of increase in cardiac burden. Development of therapies to improve cardiac function, therefore, is an urgent issue. This single-arm, open-label, multicenter study will include 20 patients with MD aged 13 years or older. Tranilast, a transient receptor potential cation channel subfamily V member 2 (TRPV2) inhibitor, will be administered orally for a period of 28 weeks at a dose of 300 mg/day divided into three daily doses. If consent to continue administration is obtained at 28 weeks, the drug will be administered for an additional 116 weeks. The primary outcome will be the change in brain natriuretic peptide (BNP) at 6 months after the start of administration compared to baseline. Tranilast is an anti-allergy agent that was developed in Japan. It has been used in a large number of clinical cases, including pediatric cases, and has been shown to be safe. We expect this study to provide basic data for developing new treatment method in cardiomyopathy/skeletal myopathy using TRPV2 inhibitors. Moreover, such therapies may also be effective in treating general heart failure without MD. Therefore, if the effectiveness of TRPV2 inhibitors could be confirmed in this study, great social and economic benefits could be achieved.

TRPV2 channel-based therapies in the cardiovascular field. Molecular underpinnings of clinically relevant therapies

The transient receptor potential (TRP) ion channel family is composed of twenty-seven channel proteins that are ubiquitously expressed in the human body. The TRPV (vanilloid) subfamily has been a recent target of investigation within the cardiovascular field. TRPV1, which is sensitive to heat as well as vanilloids, is the best characterized TRPV channel and is the namesake for the subfamily that includes six members. Research into the function of TRPV2 has suggested that it plays an important role in cardiovascular function. Over the last twenty years a greater understanding of the differences among the TRPV channels has allowed for more precise experimentation and has opened various translational opportunities. TRPV2 has been found to be a both a mechanosensor and a mediator of calcium handling and has been found to play important roles in healthy and diseased cardiomyocytes. These roles have been translated into clinical studies in patients with muscular dystrophy (both agonism and antagonism) as well as in patients with cardiomyopathy and heart failure with reduced ejection fraction. Its role as a structural protein has also been elucidated, though the clinical significance of this finding has yet to be established. Despite the clinical progress that has been made there is still a need for large, prospective randomized studies with TRPV2 channel agonists and antagonists in order to bring these basic and translational science findings to the bedside.

Accuracy of B-natriuretic peptide for the diagnosis of decompensated heart failure in muscular dystrophies patients with chronic respiratory failure

Heart failure and restrictive respiratory insufficiency are complications in muscular dystrophies. We aimed to assess the accuracy of the B-natriuretic peptide (BNP) for the diagnosis of decompensated heart failure in muscular dystrophy. We included patients with muscular dystrophy and chronic respiratory insufficiency admitted in the Intensive Care Unit of the Raymond Poincare hospital (Garches, France) for suspected decompensated heart failure. Thirtyseven patients were included, among them, 23 Duchenne muscular dystrophy (DMD) (62%), 10 myotonic dystrophy type 1(DM1) (27%). Median age was 35 years [27.5; 48.5]. 86.5% of patients were on home mechanical ventilation (HMV). Median left ventricular ejection fraction (LVEF) was 47% [35.0; 59.5]. Median BNP blood level was 104 pg/mL [50; 399]. The BNP level was significantly inversely associated with LVEF (r= –0.37, p 0.03) and positively associated with the LVEDD (left ventricular end diastolic diameter) (r=0.59, P<0.001). The discriminative value of the BNP level for the diagnosis of decompensated heart failure was high with an AUROC=0.94 (P<0.001). The best discriminating BNP threshold was 307 pg/mL (Youden index 0.85).

The BNP level measurement may add a supplemental key for the final diagnosis of decompensated heart failure.

A Pilot Study of Tranilast for Cardiomyopathy of Muscular Dystrophy

Objective Heart failure is currently the most serious complication of muscular dystrophy. The transient receptor potential cation channel, subfamily V, member 2 (TRPV2) is a stretch-sensitive Ca channel. In damaged myocytes or cardiomyocytes, TRPV2 translocates to the cytoplasmic membrane and enhances Ca influx, triggering cell damage. Evidence suggests that the inhibition of TRPV2 may be a new therapeutic target in heart failure. We found that tranilast, which is widely used as an anti-allergic drug, inhibits TRPV2. A pilot study was conducted to assess the safety and efficacy of tranilast in muscular dystrophy patients with cardiomyopathy. Methods After obtaining informed consent, two muscular dystrophy patients with advanced heart failure took tranilast (300 mg/day) for three months. Blood tests, echocardiography, electrocardiography (ECG), Holter ECG, analyses of the TRPV2 expression in peripheral mononuclear cells, and circulating micro ribonucleic acid profiling were performed to assess the safety and efficacy of tranilast. Results The brain natriuretic peptide levels decreased after treatment. The expression of TRPV2 on the cytoplasmic membrane of peripheral mononuclear cells was enhanced before treatment and was decreased after treatment. Some heart-related micro ribonucleic acids (miR-208a-5p, miR-223-3p) were elevated and then decreased after treatment. Some adverse events, including the potentiation of warfarin, the worsening of renal dysfunction, an increased heart rate and premature ventricular contractions, were observed. Conclusion Tranilast can inhibit TRPV2 and can be effective for treating heart failure, even in patients with muscular dystrophy. Although careful attention is needed, the inhibition of TRPV2 can be a new treatment target for cardiomyopathy. A multi-center trial is planned.

Markedly High B-type Natriuretic Peptide Level in a Patient with Duchenne Muscular Dystrophy and Left Ventricular Non-Compaction

A boy with Duchenne muscular dystrophy was admitted to our hospital due to a transient loss of consciousness. Transthoracic echocardiography revealed left ventricular (LV) dilatation and diffuse hypokinesis of the LV wall. The LV wall was thin, and both non-compaction of the LV wall and marked thinning of the posterior LV wall resulting from a lesion were observed. The plasma B-type natriuretic peptide (BNP) level ultimately increased to 7,795 pg/mL, and the patient died of cardiac arrest following ventricular tachycardia. Severe heart failure, a critical condition, and thinning of the LV wall may have contributed to the markedly high plasma BNP level in this case.

Brain natriuretic peptide is not predictive of dilated cardiomyopathy in Becker and Duchenne muscular dystrophy patients and carriers

Background

Cardiomyopathy is reported in Duchenne and Becker muscle dystrophy patients and female carriers. Brain Natriuretic peptide (BNP) is a hormone produced mainly by ventricular cardiomyocytes and its production is up regulated in reaction to increased wall stretching. N-terminal-proBNP (NT-proBNP) has been shown to be a robust laboratory parameter to diagnose and monitor cardiac failure, and it may be helpful to screen for asymptomatic left ventricular dysfunction. Therefore we tested whether NT-proBNP can distinguish patients with Duchenne or Becker muscular dystrophy patients and carriers of a dystrophin mutation with a dilated cardiomyopathy from those without.

Methods

In a cohort of Duchenne and Becker muscle dystrophy patients (n = 143) and carriers (n = 219) NT-proBNP was measured, and echocardiography was performed to diagnose dilated cardiomyopathy (DCM).

Results

In total sixty-one patients (17%) fulfilled the criteria for DCM, whereas 283 patients (78%) had an elevated NT-pro BNP. The sensitivity of NT-proBNP for DCM in patients or carriers was 85%, the specificity 23%, area under the ROC-curve = 0.56. In the specified subgroups there was also no association.

Conclusion

Measurement of NT-pro BNP in patients suffering from Duchenne or Becker muscular dystrophy and carriers does not distinguish between those with and without dilated cardiomyopathy.

Predicting scores for left ventricular dysfunction in Duchenne muscular dystrophy

BACKGROUND

The aim of this study was to predict left ventricular (LV) dysfunction and the timing to perform echocardiography in patients with Duchenne muscular dystrophy (DMD). We developed a scoring system using clinical parameters and examined its efficacy. It is indispensable to utilize echocardiogram for evaluating myocardial damage of DMD patients, but there is no established guideline for determining the clinical conditions which require echocardiographic examination.

METHODS

We retrospectively analyzed 86 patients with DMD who were treated in Kobe University Hospital from 2007 to 2009. The multiple logistic regression analysis on routine clinical data was performed to identify parameters that can find abnormal LV contraction, and to develop a weighted scoring system. Echocardiogram was performed as the gold standard for detecting LV dysfunction.

RESULTS

Four parameters were associated with abnormal LV contraction: (i) brain natriuretic peptide (BNP); (ii) creatine kinase; (iii) scoliosis; and (iv) body surface area. When BNP was used as the only predictor to evaluate LV systolic dysfunction, sensitivity and specificity were 36.4% and 92.1%, respectively. In contrast, abnormal LV contraction was detected in high accuracy (sensitivity: 95.5%; specificity: 68.3%) when we used a two-step scoring system in which BNP was combined with the other three factors, raising the sensitivity compared to using BNP levels as the single parameter (P= 0.008).

CONCLUSION

Our scoring system detects the early heart dysfunction of DMD patients, especially when BNP level is not elevated. This system is useful to determine the timing for echocardiographic examination and consulting cardiologists.

[Renal dysfunction is a frequent complication in patients with advanced stage of Duchenne muscular dystrophy]

Mechanical ventilation and cardioprotective therapy have significantly improved the prognosis and quality of life of patients with Duchenne muscular dystrophy (DMD). The incidence of congestive heart failure is on declining trend by meticulous care. Meanwhile, elongation of decreased cardiac function can provoke instability in circulation. Recently, we experienced six DMD patients who died from acute renal failure with preserved cardiac function (brain natriuretic peptide: BNP <100 pg/ml, fractional shortening: FS >15% and left ventricular diameter: LVD <50mm). In some patients, hypovolemia induced by low water intake, diarrhea or dose-up of diuretics was thought to be a trigger of renal failure. Since the value of creatinine (Crnn) decreased in amyotrophic patients, we evaluated renal function in 103 patients with DMD using cystatin C (CysC), which is a sensitive renal marker and unaffected by muscle volume. In addition, we assessed β2-microglobulin (b2MG) in 24 patients, because it is also unaffected by muscle volume. The correlation between logarithm of CysC (LogCysC) and logarithm of b2MG was quite high (r=0.954), though that between LogCysC and logarithm of Crnn was not adequate (r=0.623). The average of CysC increased along with age, and more than 30% of patients over 30 years old showed abnormal values. Hemoglobin and logCysC was also negatively associated (r=-0.519), and patients with hemoglobin less than 10 g/dl showed elevated values of CysC. Cardiac indices such as FS (r=-0.250) and logarithm of BNP (r=0.319) showed weak correlations with logCysC, though significant correlation was not detected between LVD and LogCysC. Since renal dysfunction is a common complication in advanced stage of DMD patients, proper managements of water balance and anemia is important. In the medical managements for DMD, we should pay attention to cardiac-renal-anemia association.

Cardiac assessment of patients with late stage Duchenne muscular dystrophy

Background. Duchenne muscular dystrophy (DMD) patients used to die mainly from pulmonary problems. However, as advances in respiratory care increase life expectancy, mortality due to cardiomyopathy rises. Echocardiography remains the standard diagnostic modality for cardiomyopathy in DMD patients, but is hampered by scoliosis and poor echocardiographic acoustic windows in adult DMD patients. Multigated cardiac radionuclide ventriculography (MUGA) does not suffer from these limitations. N-terminal proBNP (NTproBNP) has shown to be a diagnostic factor for heart failure. We present our initial experience with plasma NT-proBNP measurement in the routine screening and diagnosis of cardiomyopathy in adult mechanically ventilated DMD patients.Methods. Retrospective study, 13 patients. Echocardiography classified left ventricular (LV) function as preserved or depressed. NT-proBNP was determined using immunoassay. LV ejection fraction (LVEF) was determined using MUGA.Results. Median (range) NT-proBNP was 73 (25 to 463) ng/l. Six patients had an NT-proBNP >125 ng/l. Seven patients showed an LVEF <45% on MUGA. DMD patients with depressed LV function (n=4) as assessed by echocardiography had significantly higher median NT-proBNP than those (n=9) with preserved LV function: 346 (266 to 463) ng/l versus 69 (25 to 257) ng/l (p=0.003). NT-proBNP significantly correlated with depressed LV function on echocardiogram and with LVEF determined by MUGA.Conclusion. Although image quality of MUGA is superior to echocardiography, the combination of echocardiography and NT-proBNP achieves similar results in the evaluation of left ventricular function and is less time consuming and burdensome for our patients. We advise to add NT-proBNP to echocardiography in the routine cardiac assessment of DMD patients. (Neth Heart J 2009;17:232-7.).

N-terminal Pro brain natriuretic peptide is a reliable biomarker of reduced myocardial contractility in patients with lamin A/C gene mutations

BACKGROUND

Recently, concerns have been raised about a possible lack of sensitivity of biomarkers to detect left ventricular (LV) dysfunction in patients with myopathies. We examined the ability of the N-terminal brain natriuretic peptide (NT-proBNP) to detect LV or right ventricular (RV) dysfunction in patients with lamin A/C (LMNA) gene mutations.

METHODS

We prospectively measured plasma NT-proBNP in consecutive patients with documented LMNA mutations and age-sex matched controls. All patients underwent standard echocardiography implemented by pulsed tissue-Doppler echocardiography (TDE).

RESULTS

Twenty-three patients were included (10 males, mean age 39.2 ± 18.9 years);10 had previous atrial arrhythmias, 8 had been implanted with cardioverter defibrillator for primary prevention of sudden death, 5 patients were of NYHA class II and 18 of NHYA class I. Sinus rhythm was recorded in all. NT-proBNP was increased in LMNA patients versus controls (123 ± 229 versus 26 ± 78 pg/ml, p=0.0004); 7 patients had depressed LV and/or RV contractility. Patients with reduced LV or RV contractility had increased mean NT-proBNP (341 ± 1032 pg/ml versus 80 ± 79 pg/ml in patients with normal myocardial contractility, p=0.004). Receiver-operating-characteristics analysis shows that NT-proBNP reliably detected depressed contractility (area under the curve 0.889 [0.697-1.000]). Sensitivity and specificity were 88% and 83% respectively, applying manufacturer's recommended cut-off concentration of 125 pg/ml.

CONCLUSION

NT-proBNP reliably detected the presence of reduced LV/RV contractility in LMNA patients.

Carvedilol can prevent cardiac events in Duchenne muscular dystrophy

OBJECTIVE

Heart failure is one of the most serious complications in Duchenne muscular dystrophy (DMD). Beta-blocker medication is known to improve the prognosis of chronic heart failure of adults, but its efficacy and safety for DMD patients has not been fully assessed. Thus we conducted a multicenter open trial.

METHODS

Fifty-four DMD patients participated; 41 received carvedilol (BB group) and 13 did not (non BB group). All patients with an ejection fraction of less than 50% received angiotensin-converting enzyme inhibitor. Then, patients in BB group were started on carvedilol. The mean maintenance dose of carvedilol in BB group was 7.85+/-2.80 mg/day. Clinical signs and cardiac function were monitored regularly and statistical analysis was done.

RESULTS

The survival rate free from primary endpoints (death, deterioration of heart failure and severe arrhythmia) was higher in the BB group. The survival rate free from all-cause death was also higher in the BB group, although not significantly higher. Patients with primary endpoints received lower maintenance doses of carvedilol and presented higher mean heart rates (HR) during the observation period. In the BB group, mean HR at enrollment and the reduction of mean HR were correlated with the change of ejection fraction. Although serious adverse events were rare during the introduction of carvedilol, patients with advanced cardiac dysfunction required a longer period for up-titration and frequently presented with minor complaints.

CONCLUSION

The present study suggests that carvedilol is relatively safe and can prevent cardiac events even in patients with DMD.

Cardiac involvement in Becker muscular dystrophy

The present review gives an overview of the clinical and subclinical manifestations of cardiac involvement (CI) in Becker muscular dystrophy (BMD), its pathophysiological background, diagnostic possibilities and therapeutic options for CI in BMD patients and carriers. CI may be subclinical or symptomatic. Up to 100% of patients develop subclinical CI. The onset of symptomatic CI is usually in the third decade of life, rarely in the first decade. One-third of patients develop dilative cardiomyopathy with concomitant heart failure. In BMD patients, CI manifests as electrocardiographic abnormalities, hypertrophic cardiomyopathy, dilation of the cardiac cavities with preserved systolic function, dilative cardiomyopathy or cardiac arrest. There is no correlation between CI and the severity of myopathy. CI is more prominent in patients than carriers. As soon as the diagnosis of BMD is established, a comprehensive cardiac examination should be performed. Because CI in BMD is progressive and adequate therapy is available, cardiac investigations need to be regularly repeated. If CI in BMD is recognized early, appropriate therapy may be applied early, resulting in a more favourable outcome.

Cardiac troponin I for accurate evaluation of cardiac status in myopathic patients

BACKGROUND

Brain natriuretic peptide (BNP) and left ventricular ejection fraction (LVEF) are standard indexes for cardiac function. However, they can not reveal myocardial damage directly and they often remain normal even in advanced cardiomyopathy in immobilized patients. Myocardial markers such as MB type of creatine kinase (CK-MB), heart-type fatty acid binding protein (H-FABP) and cardiac troponins are expected to evaluate active myocardial degeneration. However, their availabilities in these patients have not been examined yet.

METHODS

Participants were 129 patients with dystrophinopathies; 100 Duchenne muscular dystrophy (DMD), 25 Becker muscular dystrophy (BMD) and 4 DMD/BMD carriers. Various serological cardiac indexes, including CK-MB, H-FABP, cardiac troponin I (cTnI), BNP and LVEF were measured and statistical analysis was done.

RESULTS

CK-MB and H-FABP was highly associated with creatine kinase (CK). On the contrary, cTnI, BNP and LVEF were independent from CK. In DMD, relatively high cTnI values were observed in patients with motor ability of rowing wheelchair and in their second decade. BNP and LVEF was strongly correlated. However, cTnI was independent from LVEF and only weak correlation could be detected between cTnI and BNP.

CONCLUSION

cTnI had been proven to be expressed in myocardium exclusively. Our results also certified that cTnI can assess cardiac degeneration independently from skeletal muscle degeneration and is practical index even in myopathic patients. Our findings also suggested that cardiac degeneration was preceded to functional impairment in many cases. It indicated that cTnI enable us to detect early stage of cardiac degeneration and initiate intervention at proper stage.

Beta-blocker therapy for cardiac dysfunction in patients with muscular dystrophy

BACKGROUND

In muscular dystrophy, cardiac function deteriorates with time and heart failure is one of the major causes of death. Although the combination of angiotensin-converting enzyme inhibitors (ACEI) and beta-blockers improves cardiac function in adults, little is known about the efficacy of those drugs in patients with muscular dystrophy.

METHODS AND RESULTS

The effect of the beta-blocker, carvedilol, and/or ACEI on ventricular function in patients with muscular dystrophy was studied. Carvedilol and an ACEI were given to 13 patients (ACEI group; mean age 18 years, range 7-27 years), and an ACEI only to 15 patients (carvedilol group; mean age 15 years, range 8-29 years). Diagnoses included Duchenne muscular dystrophy (n=25), Fukuyama muscular dystrophy (n=2), and Emery-Dreifuss muscular dystrophy (n=1). Echocardiographic parameters of the left ventricle were measured during the 2-3 years of follow-up. In the carvedilol group, combination therapy of carvedilol and an ACEI for 2 years resulted in a significant increase in left ventricular fractional shortening (LVFS). In the ACEI group, there was no significant change in LVFS. Left ventricular end-diastolic dimension increased in the ACEI group, but not in the carvedilol group.

CONCLUSION

Carvedilol plus an ACEI improves left ventricular systolic function in patients with muscular dystrophy.