Daigo Nagahara

Predicting the Need for an Implantable Cardioverter Defibrillator Using Cardiac Metaiodobenzylguanidine Activity Together with Plasma Natriuretic Peptide Concentration or Left Ventricular Function

Despite widespread use of implantable cardioverter defibrillators (ICDs), their cost and the fact that only a certain group of patients fully benefits from the devices require appropriate risk stratification of patients. This study investigated whether altered cardiac autonomic function is associated with the occurrence of ICD discharge or lethal cardiac events. Methods: Fifty-four ICD-treated patients were prospectively followed after assessment of cardiac metaiodobenzylguanidine (MIBG) activity, quantified as the heart-to-mediastinum ratio (HMR), plasma concentration of brain natriuretic peptide (BNP), and left ventricular ejection fraction (LVEF). Patients were divided into 2 groups based on the presence (group A, n = 21) or absence (group B, n = 33) of appropriate ICD discharge during a 15-mo period. Results: Group A had a significantly lower level of MIBG activity and a higher plasma BNP level than did group B. Univariate analysis revealed BNP level, any medication, and late HMR to be significant predictors, and multivariate analysis showed late HMR to be an independent predictor. An HMR of less than 1.95 with a plasma BNP level of more than 187 pg/mL or an LVEF of less than 50% had significantly increased power to predict ICD shock: positive predictive values, 82% (HMR + BNP) and 58% (HMR + LVEF); negative predictive values, 73% (HMR + BNP) and 77% (HMR + LVEF); sensitivities, 45% (HMR + BNP) and 67% (HMR + LVEF); and specificities, 94% (HMR + BNP) and 70% (HMR + LVEF). Conclusion: When combined with plasma BNP concentration or cardiac function, cardiac MIBG activity is closely related to lethal cardiac events and can be used to identify patients who would benefit most from an ICD.

Impaired Cardiac Sympathetic Innervation and Myocardial Perfusion Are Related to Lethal Arrhythmia: Quantification of Cardiac Tracers in Patients with ICDs

Despite widespread prophylactic use of implantable cardioverter defibrillator (ICD) therapy, sudden cardiac death and refractory arrhythmia events are still important clinical issues to be overcome. We examined whether the impairment of cardiac sympathetic innervation and myocardial perfusion is responsible for lethal arrhythmic events and has prognostic value by comparing conventional clinical indices. Methods: In consecutive ICDs implanted in 60 patients, cardiac uptake of 123I-metaiodobenzylguanidine and 99mTc-tetrofosmin at rest was quantified, and then patients were prospectively followed with endpoints of appropriate ICD shocks or cardiac death. Cardiac metaiodobenzylguanidine activity was quantified as a heart-to-mediastinum ratio (HMR), and impaired tetrofosmin uptake was graded as a summed score (SS) using a computerized technique with a percentage of tracer uptake. Results: During a mean 29-mo interval, ICD shock was documented in 30 patients (50%); 3 cardiac deaths were also observed in this group of patients. Patients with ICD shocks had a significantly smaller HMR and a greater SS than did those without (1.73 ± 0.34 vs. 2.06 ± 0.46, P = 0.003, and 18.0 ± 16.2 vs. 5.7 ± 4.4, P = 0.001, respectively). Kaplan–Meier analysis showed that patients who had both an HMR of 1.90 or less and an SS of 12 or greater had a significantly greater ICD discharge rate than did those who had both an HMR greater than 1.90 and an SS less than 12 (94% vs. 18%, P < 0.005) (log rank, 15.14; P < 0.0005). Multivariate analysis with a Cox model identified the greatest Wald χ2 of 6.454 and a hazard ratio of 3.857 (P = 0.011) when an HMR of 1.9 or less and tetrofosmin SS of 12 or greater were combined. Conclusion: Impairment of cardiac sympathetic innervation and myocardial perfusion is related to lethal arrhythmic events leading to sudden death, and the combined assessment of these can identify patients for whom prophylactic ICD use has the greatest potential.

Assessment of Cardiac Sympathetic Innervation in Heart Failure and Lethal Arrhythmias: Therapeutic and Prognostic Implications

Sympathetic nerve activities have pivotal roles in pathophysiology and prognosis in patients with heart failure. Among the various available techniques for the analysis of sympathetic nerve function, cardiac neuroimaging with a norepinephrine analogue is a noninvasive, specific and powerful modality that enables in vivo assessment of cardiac sympathetic innervation and activity and has demonstrated pathophysiological alterations at pre-synaptic nerve terminals and their clinical implications. Impaired cardiac metaiodobenzylguanidine (MIBG) activity and, conversely, increased systemic sympathetic function drive closely correlate with clinical outcomes. Cardiac MIBG activities have independent but incremental prognostic values in combination with known clinical determinants in patients with heart failure. Systemic inhibition of sympathetic drive and the rennin-angiotension-aldosterone system can improve cardiac MIBG activity and kinetics together with functional improvement in heart failure patients. Prognostic efficacy of contemporary drug treatment is, however, likely to depend on the severity of the impairment of cardiac MIBG activity. Patients who have impaired cardiac MIBG activity with blunted heart rate variability, an elevated brain natriuretic peptide level or LV dysfunction are likely to have appropriate discharges of an implantable cardioverter defibrillator. Thus, cardiac neuroimaging could enable appropriate selection of patients at greater risk for lethal outcomes, who can probably benefit most from pharmacological and invasive strategies.

Worsening of mitral valve regurgitation after radiofrequency catheter ablation of ventricular arrhythmia originating from a left ventricular papillary muscle

Introduction Papillary muscles (PMs) of the left ventricle (LV) have been shown to be a potential origin of ventricular arrhythmias (VAs) in patients with or without structural heart disease. Recently, a “malignant” arrhythmia phenotype in patients with mitral valve prolapse (MVP) who experienced lifethreatening VAs has been reported. This subset of patients with MVP was characterized by complex ventricular ectopy arising from one or both of the PMs, fascicular tissue, and outflow tracts, and the arrhythmias have been shown to be successfully treated by catheter ablation (CA). Mitral valve dysfunction after radiofrequency (RF) CA of VAs of PM origin has been described in only 1 report, to our knowledge. Here we report a patient with a history of MVP and nonsustained ventricular tachycardia (NSVT) originating from the left ventricular posterior PM (PPM). Her ventricular tachycardia (VT) was successfully eliminated by repeated RF CA, but mitral valve regurgitation (MR) worsened from moderate to severe after CA. She underwent mitral valvuloplasty 8 months after the first CA session.

Predictors of appropriate ICD therapy in Japanese patients with structural heart diseases: A major role of prior sustained ventricular tachycardia in secondary prevention

Implantable cardioverter defibrillator (ICD) and cardiac resynchronization with a defibrillator (CRT‐D) are established therapies for secondary prevention of sudden cardiac death (SCD) in patients with structural heart disease (SHD), but the rates of subsequent ICD/CRT‐D therapy widely differ among patients with SHD. The aim of this study was to determine clinical factors associated with appropriate therapy for preventing SCD in patients with SHD.

Successful Transcatheter Diagnosis and Medical Treatment of Right Atrial Involvement in IgG4-related Disease: A Case Report and Review of the Literature

IgG4-related disease (IgG4-RD) is a fibro-inflammatory disorder characterized by lymphoplasmacytic infiltration of numerous IgG4-positive plasma cells, leading to fibrous thickening in the affected tissue. Typical cardiovascular manifestations of IgG4-RD are periaortitis, coronary arteritis, and pericarditis. Rare cases of myocardial involvement in IgG4-RD have been reported, but surgical resection or open biopsy was required for the diagnosis in those cases. Here, we report a case in which percutaneous transcatheter biopsy under the guidance of intracardiac echocardiography was useful for diagnosis of IgG4-RD manifested as an intracavitary right atrial mass, extending into the superior vena cava. Successful transcatheter diagnosis of myocardial involvement of IgG4-RD led to immediate favorable response to steroid therapy. Including the present case, previous IgG4-RD cases with myocardial involvement are reviewed to delineate its clinical characteristics.

Lethal heart failure with anti-mitochondrial antibody: an arrhythmogenic right ventricular cardiomyopathy mimetic

A 60-year-old woman with heart failure and no family history of cardiomyopathy/sudden death was referred to our hospital. Echocardiography revealed large pericardial effusion and thinning of akinetic right ventricular free wall ( Panel s A and B ). Serum biochemistry showed low level of free thyroxine with elevation of thyroid-stimulating hormone level, elevated …