Increased amount of interstitial fibrosis predicts ventricular arrhythmias, and is associated with reduced myocardial septal function in patients with obstructive hypertrophic cardiomyopathy.

AIMS: Reduced echocardiographic strain is associated with ventricular arrhythmias in hypertrophic cardiomyopathy (HCM) patients. The aim of this cross-sectional study was to investigate which type of histological fibrosis contributes to ventricular arrhythmias and reduced septal longitudinal strain, in obstructive HCM-patients with or without additional coronary artery disease (CAD) and/or hypertension (HT). METHODS AND RESULTS: Sixty-three HCM-patients (mean age 57 ± 13 years) were included. Strain by speckle tracking echocardiography was performed prior to either percutaneous transluminal septal ablation (n = 37) or septal myectomy (n = 26). In 24 patients myectomy specimens were available (histology population) and allowed determination of %area of interstitial and replacement fibrosis. Twenty-nine (46%) patients had concomitant CAD and/or HT, and 15 (24%) experienced ventricular arrhythmias defined as documented ventricular tachycardia or arrhythmogenic suspected syncope. The patients with ventricular arrhythmias had lower septal longitudinal strain compared with those without arrhythmias (-9.0 ± 4.0 vs. -13.6 ± 5.6%, P = 0.006). In the histology population reduced septal longitudinal strain correlated to interstitial (R(2) = 0.36 P = 0.003), but not to replacement fibrosis (R(2) = 0.03 P = 0.43). By logistic regression analyses, interstitial fibrosis predicted ventricular arrhythmias (OR 1.16, 95% CI 1.02-1.32, P = 0.03), while replacement fibrosis did not (OR 1.22, 95% CI 0.93-1.59, P = 0.15). CONCLUSION: Total amount of fibrosis was a marker of ventricular arrhythmias in obstructive HCM-patients. Interstitial fibrosis seemed to be more important compared with replacement fibrosis in arrhythmogenesis, and was related to reduced septal myocardial function. These findings suggest that interstitial fibrosis may play an important role as the arrhythmogenic substrate, and that strain echocardiography can help detection of patients at risk.

The Wedensky test predicts malignant ventricular arrhythmias after myocardial infarction.

OBJECTIVES: Better tools are needed for detection of future malignant ventricular arrhythmias post myocardial infarct (MI). Wedensky Modulation (WM) is a new semi-invasive method: A short low-amplitude electrical impulse is applied synchronized to the QRS between a precordial and dorsal thoracic patch, and changes in the following QRS-T are registered. DESIGN: A total of 357 (MI) ICD patients underwent WM testing. QRS-T wavelet analysis provided WM Indexes for the QRS complex (WMI-R) and T wave (WMI-T). Outcome was the time to first occurrence of appropriate device therapy for ventricular arrhythmia. Patients were followed at 6-month intervals for 2 years. RESULTS: No arrhythmia was induced by the testing. Two-year appropriate arrhythmia treatment occurred in 35% (WMI-R positive) versus 25% (WMI-R negative, p = 0.014), and. 45% versus 26% (p = 0.001) for WMI-T positive versus negative. Two-year event rates of WMI-R or WMI-T positive versus WMI-R and WMI-T negative were 36% versus 22% (p = 0.004). In Cox proportional hazard model, the combination of WMI-R and WMI-T was the only statistically significant event predictor (p = 0.003). CONCLUSION: Potentially life-threatening ventricular arrhythmic events could be predicted by the WM test. In combination with other risk factors WMI may be useful in these patients.

Cardiac function and antiepileptic drug treatment in the elderly: a comparison between lamotrigine and sustained-release carbamazepine.

PURPOSE: To investigate the comparative effects of carbamazepine (CBZ) and lamotrigine (LTG) on electrocardiography (ECG) parameters in elderly patients with newly diagnosed epilepsy. METHODS: The study was conducted in the Norwegian subcohort (n = 108) of an international randomized double-blind 40-week trial, which compared the efficacy and tolerability of LTG and sustained-release CBZ in patients aged 65 and older with newly diagnosed epilepsy. Target maintenance doses were 400 mg/day for CBZ and 100 mg/day for LTG, with adjustments based on clinical response. Patients with significant unpaced atrioventricular (AV) conduction defect were excluded. Resting 12-lead ECG recordings were made under standardized conditions at pretreatment (baseline) and at the 40-week study visit (treatment visit). Changes in QRS interval (primary endpoint), heart rate (HR), PQ, and QTc (HR-corrected QT) intervals were assessed and compared between groups. RESULTS: Of the 108 patients randomized, 33 discontinued prematurely because of adverse events (n = 24, none of which was cardiac) or other reasons (n = 9), and 15 were nonevaluable due to incomplete ECG data. None of the assessed ECG parameters differed significantly between groups at baseline. No significant ECG changes were recorded between baseline and treatment visit for QRS duration and QTc intervals, whereas HR fell and PQ intervals increased slightly on both treatments. However, there were no differences between groups in changes from baseline to treatment visit. There were no significant relationships between individual ECG changes and serum drug concentrations, except for QTc intervals, which decreased slightly with increasing CBZ concentrations. The proportion of patients with ECG parameters outside the normal range at treatment visit was similar to that recorded at baseline. DISCUSSION: Clinically significant ECG changes are not common during treatment with CBZ or LTG in elderly patients with no preexisting significant AV conduction defects.

[Cardiac ion channel disorders--diagnosis and treatment]. / Kardiale kanalopatier--diagnostikk og behandling.

BACKGROUND: Inherited arrhythmogenic disorders are a group of genetically determined diseases characterised by ventricular tachyarrhythmias sometimes leading to sudden death. The molecular bases of these disorders are mutations in genes coding for various cardiac ion channels. The most common cardiac ion channel disease is the long QT syndrome. This syndrome is rare, but probably more common in Norway than previously expected. We have recently started genetic testing for cardiac ion channel disorders at Rikshospitalet University Hospital in Oslo. This review describes the current understanding of the etiology, prognosis and management of cardiac ion channel disorders, based on literature and our own clinical experience. INTERPRETATION: Cardiac ion channel disorders may lead to sudden cardiac death. Prophylactic and life-saving therapies are available for many of these disorders. Therapy and risk stratification depend on the clinical presentation, the ECG pattern, and which gene is mutated. Genetic testing offers the opportunity to exclude individual family members as mutation carriers.

Noninvasive assessment of myocardial fibrosis in patients with obstructive hypertrophic cardiomyopathy.

OBJECTIVE: Late gadolinium enhancement cardiac magnetic resonance (LGE-CMR) imaging is the reference standard for non-invasive assessment of fibrosis. In hypertrophic cardiomyopathy (HCM) patients the histological substrate for LGE is still unknown. The aim of this study was to assess the ability of LGE and strain echocardiography to detect type and extent of myocardial fibrosis in obstructive HCM patients undergoing septal myectomy. METHODS: Thirty-two HCM patients (age 60±10) were included in this cross-sectional study and preoperatively examined by speckle-tracking strain echocardiography and LGE-CMR (n=21). Histological fibrosis was classified as interstitial, replacement and total. RESULTS: Histological fibrosis was present in 31 patients. The percentage of total, interstitial and replacement fibrosis was 15(7, 31)%, 11(5, 24)% and 3(1, 6)%, respectively. Reduced longitudinal septal strain correlated with total (r=0.50, p=0.01) and interstitial (r=0.40, p=0.03), but not with replacement fibrosis (r=0.28, p=0.14). Septal LGE was detected in 13/21 (62%), but percentage LGE did not correlate with total fibrosis (r=0.25, p=0.28). Extent of fibrosis did not differ between patients with and without septal LGE (20(9, 58)% versus 14(5, 19)% p=0.41). Patients with ventricular arrhythmias (n=8) had lower septal longitudinal strain and increased extent total and interstitial fibrosis in myectomy specimens, but no differences were demonstrated in LGE. Reduced longitudinal septal strain and increased extent of interstitial fibrosis predicted ventricular arrhythmias independently of age and gender. CONCLUSIONS: In myectomised HCM patients, reduced longitudinal septal strain correlated better with interstitial and total fibrosis in myectomy specimens, and was a more powerful tool to predict arrhythmias than LGE.

Abnormal electroencephalograms in patients with long QT syndrome.

BACKGROUND: The long QT syndrome (LQTS) is an inherited cardiac channelopathy associated with syncope and sudden cardiac death due to ventricular arrhythmias. It is most frequently caused by potassium channel mutations. Potassium channels are also expressed in brain tissue and play an important role in idiopathic epilepsies. Recent reports have indicated that related potassium channel mutations may coexpress as concomitant epilepsy and LQTS. OBJECTIVE: The purpose of this study was to explore cerebral activity by means of EEG recordings in individuals with LQTS related to potassium channel mutations. METHODS: Seventeen individuals with confirmed LQTS related to potassium channel mutations (11 LQT1 and 6 LQT2) were prospectively studied with 21-channel electroencephalography (EEG) LQTS -related symptoms, comorbidity, medication, and QTc (12-lead ECG) were recorded. Sixteen healthy individuals previously studied with EEG served as a control group. All EEGs were reviewed by two independent neurophysiologists. RESULTS: EEG recordings were abnormal in 12 of 17 patients (71%) in the LQTS group, whereas abnormalities were present in only 2 of 16 healthy controls (13%; P <.01). In the LQTS group, all abnormal EEGs showed a combination of theta activity and sharp waves. Two patients showed additional delta activity. None of the patients had definite epileptic activity (spikes, spike waves). CONCLUSION: Abnormal electrical cerebral activity was identified more frequently in subjects with LQTS secondary to a potassium channel mutation compared with healthy controls. This result indicates a possible link between cardiac and cerebral channelopathy.

Long-term outcome of percutaneous transluminal septal myocardial ablation in hypertrophic obstructive cardiomyopathy: a Scandinavian multicenter study.

BACKGROUND: Single-center reports on percutaneous transluminal septal myocardial ablation (PTSMA) in patients with hypertrophic obstructive cardiomyopathy have shown considerable differences in outcome. METHODS AND RESULTS: We report the long-term outcome of 313 PTSMA procedures performed in 279 patients with hypertrophic obstructive cardiomyopathy aged 59±14 years from 1999 to 2010 in 4 Scandinavian centers. Sixty-nine percent of patients had ≥1 comorbidity at baseline. The median (interquartile range) of left ventricular outflow tract gradient at rest was reduced from 58 mm Hg (34 to 89 mm Hg) at baseline to 12 mm Hg (8 to 24 mm Hg) at 1-year (P<0.001) and during Valsalva maneuver from 93 mm Hg (70 to 140 mm Hg) to 21 mm Hg (11 to 42 mm Hg) (P<0.001). The proportion of patients with syncope was reduced from 18% to 2% (P<0.001), and the proportion in New York Heart Association class III/IV was reduced from 94% to 21% (P<0.001). All treatment effects remained stable during the follow-up. New York Heart Association class III/IV at the most recent follow-up (2.9±2.6 years) was associated with diabetes mellitus (P=0.03), chronic obstructive pulmonary disease (P=0.02), and valve disease unrelated to hypertrophic cardiomyopathy (P<0.01). In-hospital mortality was 0.3%. The 1-, 5- and 10-year survival rates were 97%, 87%, and 67%, respectively (P=0.06 versus an age- and sex-matched background population) in all patients and 99%, 94%, and 88%, respectively (P=0.12) in patients aged <60 years (48±9 years, n=141). Age (hazard ratio, 1.07; 95% CI, 1.03 to 1.1) was the only predictor of survival. CONCLUSIONS: In this multicenter study, the in-hospital mortality after PTSMA was low despite considerable comorbidities. The hemodynamic and symptomatic effects were sustained long term. The long-term symptomatic outcome was associated with baseline comorbidities. The 10-year survival rate was comparable to that in an age- and sex-matched background population, and age was the only predictor of survival.

Genetic testing in specific cardiomyopathies.

An increasing number of genetic tests for cardiomyopathies are becoming available for clinical use. This commentary will give a short overview of indications and challenges concerning genetic testing for these conditions.

Implantable cardioverter defibrillator dysfunction during and after magnetic resonance imaging.

This report describes a patient in whom a MRI of the brain was performed without realizing that an ICD had been implanted 8 days previously. Electromagnetic noise induced during the MRI was detected as ventricular fibrillation and nearly caused inappropriate shocks. Charge time during MRI was prolonged. The battery indicator switched to "end of life," but this was reversed by capacitor reformation. These problems could have been avoided by inactivating the ICD prior to MRI. Three months later, the pacing threshold increased from 0.4 V per 0.5 ms at implantation to 2.8 V per 0.5. It is still uncertain whether radiofrequency current heating at the electrode tip caused the increased pacing threshold or if this would have occurred independently of the MRI. MRI of patients with an active ICD may cause life-threatening complications, and it is unknown if MRI may be safely performed if the ICD is inactivated. Therefore, MRI of patients with an ICD remains contraindicated.