Quality and utility of [123I]I-metaiodobenzylguanidine cardiac SPECT imaging in nondiabetic postinfarction heart failure patients qualified for implantable cardioverter defibrillator.

OBJECTIVE: Impaired cardiac adrenergic activity has been demonstrated in heart failure (HF) and in diabetes mellitus (DM). [123I]I-metaiodobenzylguanidine (MIBG) enables assessment of the cardiac adrenergic nervous system. Tomographic imaging of the heart is expected to be superior to planar imaging. This study aimed to determine the quality and utility of MIBG SPECT in the assessment of cardiac innervation in postinfarction HF patients without DM, qualified for implantable cardioverter defibrillator (ICD) in primary prevention of sudden cardiac death. METHODS: Consecutive patients receiving an ICD on the basis of contemporary guidelines were prospectively included. Planar MIBG studies were followed by SPECT. The essential analysis was based on visual assessment of the quality of SPECT images ("high", "low" or "unacceptable"). The variables used in the further analysis were late summed defect score for SPECT images and heart-to-mediastinum rate for planar images. MIBG images were assessed independently by two experienced readers. RESULTS: Fifty postinfarction nondiabetic HF subjects were enrolled. In 13 patients (26%), the assessment of SPECT studies was impossible. In addition, in 13 of 37 patients who underwent semiquantitative SPECT evaluation, the assessment was equivocal. Altogether, in 26/50 patients (52%, 95% confidence interval 38-65%), the quality of SPECT images was unacceptable or low and was limited by low MIBG cardiac uptake and by comparatively high, interfering MIBG uptake in the neighboring structures (primarily, in the lungs). CONCLUSIONS: The utility of MIBG SPECT imaging, at least with conventional imaging protocols, in the qualification of postinfarction HF patients for ICD, is limited. In approximately half of the postinfarction HF patients, SPECT assessment of cardiac innervation can be impossible or equivocal, even without additional damage from diabetic cardiac neuropathy. The criteria predisposing the patient to good-quality MIBG SPECT are: high values of LVEF from the range characterizing the patients qualified to ICD (i.e., close to 35%) and left lung uptake intensity in planar images comparable to or lower than heart uptake.

Ablation of atrial tachyarrhythmias late after surgical correction of tetralogy of Fallot: long-term follow-up.

BACKGROUND: After the surgical correction of tetralogy of Fallot, surgical scars and natural obstacles form pathways capable of supporting an atrial tachyarrhythmia (AT). Radiofrequency (RF) ablation is effective, although the few studies published on this topic had relatively short follow-up periods. AIM: The aims of the study were to evaluate the acute and long-term effects of RF ablation of AT and examine the charac-teristics of arrhythmia recurrence. METHODS: Tetralogy of Fallot patients (n = 16, age 44.7 ± 10.7 years) referred for ablation of ATs, appearing 25.7 ± 9.6 years after repair, were studied. RESULTS: Twenty-five ATs were ablated, including 16 cavo-tricuspid isthmus atrial flutters (CTI-AFLs) and nine intraatrial reentrant tachycardia (IART). In one patient with paroxysmal atrial fibrillation (PAF), pulmonary vein isolation was also performed. Ten patients had permanent, and six had paroxysmal arrhythmia prior to the first ablation. Four patients had PAF. Regardless of the type of first ablated arrhythmia, all 16 patients required CTI-AFL ablation. The effectiveness of the first RF ablation reached 88%. The acute efficacy of RF ablation was 100% for CTI-AFL and 78% for IART. Long-term follow-up was possible in 15 out of 16 patients (mean follow-up 68.8 ± 36.6 months). Four patients were free of sustained arrhythmia, nine (60%) had AF. After the last RF ablation, an episode suggestive of CTI-AFL/IART was documented only in one patient. CONCLUSIONS: Ablation of CTI-AFL/IART in tetralogy of Fallot patients is safe and effective. AF was observed in most patients during the long-term follow-up. Regardless of the type of the first ablated arrhythmia, all patients required CTI-AFL ablation.

Triple Percutaneous Mitral Balloon Valvuloplasty for Patients with Recurrent Mitral Valve Stenosis: Long-Term Observations.

BACKGROUND: A third percutaneous mitral balloon valvuloplasty (PMBV) may provide a means of treating symptomatic patients with re-restenosis after successful initial and second valvuloplasties, though data related to the long-term safety and efficacy of a third PMBV are lacking. The study aim was to determine the immediate and long-term clinical outcome in patients who underwent a third PMBV to treat recurrent mitral stenosis. METHODS: Among a total of 1,849 patients who underwent PMBV at the authors' institution, seven females (mean age 38.5 ± 12.2 years at the first procedure) required repeat second and third PMBVs. The mean interval between the first and second valvuloplasties was 6.4 ± 2.5 years, and between the first and third valvuloplasties was 12.5 ± 6.5 years. All procedures were performed using the Inoue balloon system. RESULTS: Second and third PMBVs resulted in a significant increase in mitral valve area (MVA), from 1.1 ± 0.1 cm2 to 1.6 ± 0.2 cm2, and from 1.0 ± 0.2 cm2 to 1.6 ± 0.4 cm2, respectively. However, as mitral degeneration progressed, four patients required mitral valve replacement (MVR) at 9.2 ± 5.8 years (range: 6-18 years) after the third PMBV. The preoperative MVA of these patients was 0.97 ± 0.1 cm2. One patient died due to surgical complications, while the fifth and sixth patients remain under clinical observation. If patients have a fourth recurrence of mitral stenosis they are no longer considered to be suitable candidates for re-PMBV. The seventh patient died at the age of 84 years. CONCLUSIONS: A repeat, third PMBV is a safe and feasible procedure in selected patients with recurrent stenosis after successful first and second valvuloplasties. Although the third procedure provides good immediate results, the long-term outcome is not satisfactory. Nonetheless, a third PMBV would allow MVR surgery to be postponed for a few years.

Influence of percutaneous pulmonary valve implantation on exercise capacity: Which group of patients benefits most from the intervention?

BACKGROUND: The aim of the study was to evaluate the role of cardiopulmonary exercise testing (CPET) parameters in assessing exercise capacity improvement after percutaneous pulmonary valve implantation (PPVI). Additionally, it aimed to determine if there are any baseline characteristics influencing that change. METHODS AND RESULTS: The study comprised 32 patients (mean age 26 ± 9); 53% males; diagnosis: tetralogy of Fallot (n = 18), pulmonary atresia (n = 6), Ross procedure (n = 4), other (transposition of great arteries, pulmonary stenosis, double outlet right ventricle, common arterial trunk type II--n = 4) who underwent successful PPVI due to right ventricular out-flow tract dysfunction (predominant pulmonary regurgitation--n = 17, predominant pulmonary stenosis--n = 15). Treadmill CPET was performed before and a year after PPVI along with clinical evaluation, cardiac magnetic resonance and transthoracic echocardiography. Twelve months post successful PPVI (pulmonary valve competence restoration and pulmonary gradient reduction from 58.8 ± 47.1 to 26.6 ± 10.8 mm Hg) there was a significant decrease in the ventilatory equivalent for CO2 at peak exercise (EQCO2) (25.3 ± 3.3 to 24.3 ± 3.0, p = 0.04) and oxygen consumption at peak exercise (pVO2) (20.4 ± 5.0 to 22.6 ± 5.3 mL/kg/min, p = 0.04). Improved EQCO2 correlated with an increase in right and left ventricular ejection fraction (respectively R = -0.57, p = 0.002; R = -0.56, p = 0.002). In this study, no baseline factors that might affect improvement in exercise function were found. CONCLUSIONS: Successful PPVI leads to an improvement in exercise capacity and hemodynamic response to exercise. The correlation between the improvement in EQCO2 or peak VO2 and baseline characteristics was too weak to reliably identify the group of patients that will benefit from the procedure.

Electrocardiographic characteristics of the right ventricle following hemodynamic improvement after percutaneous pulmonary valve implantation, one year follow-up.

Percutaneous pulmonary valve implantation (PPVI) is an alternative to open-heart surgery in patients with congenital heart defect. The purpose of the study is to evaluate right ventricle (RV) electrocardiographic characteristics in relation with hemodynamic changes after PPVI. In 30 patients (16 males, aged 24±7years), ECG RV characteristics changes (R amplitude in V1 and aVR, Sokolow-Lyon index (SL) for RV hypertrophy, QRS duration) from before and 1year after PPVI were correlated with changes in RV end-diastolic volume (RVEDV), RV end-systolic volume (RVESV), RV ejection fraction (RVEF), RV mass in cardiac magnetic resonance (cMRI) and within pulmonary gradient in echocardiography. Significant correlations were observed: decrease R amplitude in aVR correlated to decrease RVESV and RV mass; decrease RVESV and pulmonary gradient to reduction in SL-V5; increase RVEF to reduction R aVR and SL-V5. Improvement of hemodynamic parameters in cMRI and echocardiography is parallel to that of electrocardiographic criteria of RV hypertrophy.

Expanded indications for transcatheter renal denervation.

Renal denervation (RDN) is a catheter-based procedure introduced in 2009 as a treatment of resistant hypertension. The method is based on the concept that resistant hypertension is a result of hyperactivity of the sympathetic nervous system (SNS), and therefore reducing the impact of the SNS by ablating the renal nerves should eliminate the condition. Since 2009 numerous investigators have proven the procedure to be safe and effective, which contributed to the quick success and wide spread of the method, subsequently triggering further research in this area. The dynamic distribution of the procedure induced investigators to examine the influence of RDN on other conditions involving hyperactivity of the SNS (such as atrial fibrillation or ventricular arrhythmia). A few studies aiming to explain the influence of RDN on arrhythmias in patients with resistant hypertension have been conducted. The results in treating atrial fibrillation additionally to pulmonary vein ablation and electrical storm appear to be promising; however, the data are limited and further investigations needs to be done. The influence of RDN on insulin resistance, left ventricular hypertrophy and heart failure are possible. Perspectives of expanding indications are discussed. Renal denervation appears to be a promising way of treating hypertension and raises hope for a wider group of patients with conditions closely related to hyperactivity of the sympathetic nervous system such as arrhythmia.