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Background— The differential diagnosis between idiopathic and cardiomyopathy-related right ventricular outflow tract (RVOT) ventricular arrhythmias (VAs) is crucial. Signal-averaged ECG (SAECG) abnormalities are frequent in cardiomyopathy-related RVOT-VAs, although their pathophysiologic basis and diagnostic value in this setting are undefined. We tested the association between SAECG and the myocardial substrate underlying RVOT-VAs. Methods and Results— Twenty-four consecutive patients (median age, 50 years [42–59]; 12 men) with RVOT-VAs (10 with frequent [>1000/24 hours] premature ventricular contractions, 14 with ventricular tachycardias) underwent SAECG with 40-Hz filtering and electroanatomic mapping (EAM) with EAM-guided biopsy for characterization of the RVOT-VAs substrate. A filtered averaged QRS (fQRS) was obtained and analyzed for fQRS duration, low amplitude signal duration P =0.01) and LAS40 (39 ms [36–51] versus 19 ms [18–21], P =0.02), and lower RMS40 (18 µV [9–26] versus 33 µV [32–33], P =0.04). A significant linear correlation was found between the extension (cm2) of the RVOT scar and all 3 SAECG parameters (rs=0.76, P P P 2 . Conclusions— In patients with RVOT-VAs, abnormal SAECG parameters reflect the presence of extensive cardiomyopathic involvement of the RVOT. However, a negative SAECG does not reliably rule out cardiomyopathy-related RVOT-VAs in the presence of a small RVOT scar.

Objective To assess whether magnetic resonance imaging could detect any cardiac morphological or functional myocardial alterations in healthy children and young adults with ventricular arrhythmias. Methods Twenty-three subjects (14 male, mean age 15.6 +/- 6.5 years) with frequent (> or =30/h) premature ventricular complexes (PVCs) on Holter monitoring and normal echocardiographic and electrocardiographic findings underwent cardiac magnetic resonance (CMR) on a 1.5T scanner and an exercise stress test. Subjects were also followed up for a period of 71 +/- 24 months. Results CMR showed no evidence of structural cardiac abnormalities, but functional assessment revealed significant impairment in 17 subjects (74%): mild to moderate right ventricular enlargement was found in all of these subjects associated with a mild reduction of ventricular function in five cases (22%) and mild free wall and/or apex contraction abnormalities in eight subjects (35%). PVCs persisted during stress test in three subjects (13%) and disappeared in 19 (83%). No serious cardiac event was observed during the follow-up. Conclusions Our study shows that subjects with PVCs without detectable electrocardiographic and echocardiographic abnormalities frequently exhibit functional impairment of the right ventricle at CMR, potentially responsible for ventricular arrhythmias. Although the causes of these abnormalities remain to be elucidated, the long-term outcome of these subjects is excellent.

An apparently healthy 43-year-old man was submitted to cardiological evaluation for sport activity. Two-dimensional echocardiography led to suspicion of noncompaction deformity, later confirmed by magnetic resonance imaging (MRI), left ventricular catheterization and endomyocardial biopsies. To exclude life-threatening arrhythmias, the patient was submitted to an electrophysiological study and to a real-time three-dimensional electroanatomic reconstruction of left ventricle. The electroanatomic map revealed extensive area of electrical abnormalities. Extent and localization of scar areas mostly corresponded to the areas of enhancement observed at MRI. The present report is the first on electroanatomic substrate evaluation in a noncompaction left ventricle. Our findings show that ventricular noncompaction is characterized by electrical abnormalities including low voltage and scar areas, mainly related to the presence and extent of myocardial fibrosis rather than noncompacted myocardium. Electroanatomic mapping may contribute to detect and quantify fibrotic areas in patients presenting this rare cardiomyopathy.

A 50-year-old recreational futsal player was referred to our sports cardiology outpatient clinic for palpitations and detection of frequent (>5000) ventricular premature beats with bigeminy and runs of nonsustained ventricular tachycardia at 24-hour Holter monitoring. Rest ECG showed normal QRS morphology with negative T waves in precordial lateral (V4 to V6) and inferior leads (Figure 1A). Less-prominent negative T waves in lateral but not inferior leads also were present in previous ECGs obtained during routine sports preparticipation evaluation at age 26 years (Figure 1B) but in the absence of symptoms and arrhythmias at Holter monitoring; no other diagnostic test was performed at that time. Figure 1. Rest ECGs. A , Rest ECG obtained in 1984 showing negative T waves in lateral precordial leads (V4 to V6). B , Rest ECG obtained in 2010 showing more-prominent negative T waves in lateral precordial leads. A stress ECG failed to reveal ST-segment changes diagnostic for myocardial ischemia, whereas frequent polymorphic ventricular premature beats with right bundle branch block morphology and a short run of nonsustained ventricular tachycardia were observed during the recovery phase. Two-dimensional echocardiography showed a mild reduction of ejection fraction with a diffuse apical a-dyskinesia of the left ventricle (LV), whereas the right ventricle (RV) presented normal dimensions and global function but hypokinesia of the apex and …

To the Editor: We read with interest the article by Reffelmann et al1 describing a case of chloroquine-induced cardiomyopathy. Regarding the images provided by the authors, we would like to emphasize that magnetic resonance and mostly ultrastructural findings cannot univocally be referred to as chloroquine toxicity, because they might also represent …

We evaluated the hemodynamic effects of nifedipine in 10 symptomatic patients with chronic refractory heart failure due to idiopathic cardiomyopathy. Nifedipine significantly increased cardiac index (from 1.80 +/- 0.4 to 3 +/- 0.6 L/min/m2), stroke volume index (from 21 +/- 6 to 33 +/- 8 ml/beat/m2), and stroke work index (from 17.9 +/- 7 to 25.5 +/- 7 g-m/m2). The drugs also produced a significant decrease in left ventricular filling pressure (from 24.6 +/- 3 to 19 +/- 2 mm Hg), mean blood pressure (from 86 +/- 9 to 74 +/- 5 mm Hg), mean pulmonary arterial pressure (from 31.9 +/- 5 to 25.6 +/- 3 mm Hg), total systemic vascular resistance (from 2,104 +/- 329 to 1,088 +/- 249 dyn/s/cm-5), and pulmonary vascular resistance (from 200 +/- 71 to 107 +/- 50 dyn/s/cm-5). Heart rate remained unchanged. In all patients maintained on nifedipine therapy, repeat hemodynamic studies at 2 months revealed sustained effects, and all patients had symptomatic improvement of at least one New York Heart Association (NYHA) functional class. Long-term treatment was well tolerated. Forty-eight hours after discontinuation of nifedipine administration the hemodynamic benefits were lost. We conclude that nifedipine may be of value for long-term ambulatory therapy of severe chronic heart failure.