Michael C. Giudici

Cardiac resynchronization therapy for the treatment of heart failure in patients with intraventricular conduction delay and malignant ventricular tachyarrhythmias

OBJECTIVESnThis study was conducted to assess the safety and effectiveness of cardiac resynchronization therapy (CRT) when combined with an implantable cardioverter defibrillator (ICD).nnnBACKGROUNDnLong-term outcome of CRT was measured in patients with symptomatic heart failure (HF), intraventricular conduction delay, and malignant ventricular tachyarrhythmias (ventricular tachycardia/ventricular fibrillation [VT/VF]) requiring therapy from an ICD.nnnMETHODSnPatients (n = 490) were implanted with a device capable of providing both CRT and ICD therapy and randomized to CRT (n = 245) or control (no CRT, n = 245) for up to six months. The primary end point was progression of HF, defined as all-cause mortality, hospitalization for HF, and VT/VF requiring device intervention. Secondary end points included peak oxygen consumption (VO(2)), 6-min walk (6 MW), New York Heart Association (NYHA) class, quality of life (QOL), and echocardiographic analysis.nnnRESULTSnA 15% reduction in HF progression was observed, but this was statistically insignificant (p = 0.35). The CRT, however, significantly improved peak VO(2) (0.8 ml/kg/min vs. 0.0 ml/kg/min, p = 0.030) and 6 MW (35 m vs. 15 m, p = 0.043). Changes in NYHA class (p = 0.10) and QOL (p = 0.40) were not statistically significant. The CRT demonstrated significant reductions in ventricular dimensions (left ventricular internal diameter in diastole = -3.4 mm vs. -0.3 mm, p < 0.001 and left ventricular internal diameter in systole = -4.0 mm vs. -0.7 mm, p < 0.001) and improvement in left ventricular ejection fraction (5.1% vs. 2.8%, p = 0.020). A subgroup of patients with advanced HF (NYHA class III/IV) consistently demonstrated improvement across all functional status end points.nnnCONCLUSIONSnThe CRT improved functional status in patients indicated for an ICD who also have symptomatic HF and intraventricular conduction delay.

A Prospective Comparison of AV Delay Programming Methods for Hemodynamic Optimization during Cardiac Resynchronization Therapy

Introduction: There are several methods for programming the optimal AV delay (AVD) during cardiac resynchronization therapy (CRT). These include Doppler echocardiographic measurements of mitral inflow or aortic outflow velocities, an arbitrarily fixed AVD, and calculations based on intracardiac electrogram (EGM) intervals. The present study was designed to compare the acute effects of AVD programming methods during CRT.

Pacemaker and Implantable Cardioverter Defibrillator Implantation Without Reversal of Warfarin Therapy

The study evaluated all patients undergoing permanent pacemaker and ICD implantation over a 4‐year period to determine if anticoagulated patients required normalization of coagulation factors in the periprocedural period. The study included 1,025 (597 men, 428 women, age 24–100 years, mean 72 years) consecutive patients who underwent device implantation using mostly a percutaneous subclavian approach. The procedures were performed without reversal of anticoagulation in 470 patients with INRs ≥ 1.5 at the time of the procedure (mean INR 2.6 ± 1.0, range 1.5–7.5). The complication rate in the anticoagulated group was similar to those in patients with a normal INR. Routine normalization of coagulation factors prior to pacemaker/ICD placement may not be necessary. (PACE 2004; 27:358–360)

Circadian patterns in the occurrence of malignant ventricular tachyarrhythmias triggering defibrillator interventions in patients with hypertrophic cardiomyopathy

BACKGROUNDnSudden death in hypertrophic cardiomyopathy (HCM) has been reported to occur most frequently in the early morning hours, similar to the pattern observed in ischemic heart disease. However, little is known about the circadian pattern of life-threatening arrhythmias in HCM in the contemporary era of the implantable cardioverter-defibrillator (ICD).nnnOBJECTIVEnThe purpose of this study was to determine the time of day when appropriate device interventions occur for ventricular tachycardia (VT)/ventricular fibrillation (VF) in HCM patients.nnnMETHODSnAmong 63 patients with HCM and appropriate device interventions, 126 intracardiac electrograms were assessed for the hourly distribution of VT/VF.nnnRESULTSnOne or more arrhythmic episodes occurred in each hour of the day, and a modest pattern of circadian variability was evident. VT/VF episodes were more common in the afternoon and evening hours from noon to midnight (64%) than in the other 12-hour period (36%; P = .008), with the suggestion of a peak at 2 to 4 PM. A sizeable proportion of events (27%) occurred during the potential sleeping hours of 11 PM and 7 AM.nnnCONCLUSIONnIn high-risk HCM patients, the afternoon and evening circadian periodicity of ventricular tachyarrhythmias (terminated by the ICD) underscores the largely unpredictable nature of the electrophysiologic substrate in this disease, and differs from the pattern of early morning cardiovascular events reported in ischemic heart disease. These observations also suggest that home automatic defibrillator strategies for sudden death prevention are unlikely to be effective in HCM.

Phased RF ablation in persistent atrial fibrillation.

BACKGROUNDnPersistent and long-standing persistent atrial fibrillation (AF) often requires extensive and/or repeat radiofrequency (RF) ablation procedures.nnnOBJECTIVEnThe Tailored Treatment of Persistent Atrial Fibrillation (TTOP-AF) study assessed the effectiveness and safety of the phased RF system in a randomized controlled comparison of medical therapy against phased RF ablation for the management of persistent and long-standing persistent AF.nnnMETHODSnPatients who had failed at least 1 antiarrhythmic drug (AAD) were randomized (2:1) to ablation management (AM) or medical management (MM). AM patients were allowed up to 2 ablations. Index and retreatment procedures consisted of pulmonary vein isolation and ablation of complex fractionated atrial electrograms. MM patients received AAD changes and/or cardioversion. The primary end points of the TTOP-AF study included chronic effectiveness and safety at 6 months and acute safety within 7 days of ablation.nnnRESULTSnAt 6 months, a greater proportion of AM patients achieved effectiveness off AAD (77 of 138 [55.8%]) compared to MM patients (19 of 72 [26.4%]) (P < .0001). Acutely, 92.8% (128/138) of the procedures were successful while 12.3% (17/138) experienced a serious procedure and/or device-related adverse event. The predefined acute safety end point was not met. The proportion of patients with chronic safety events did not differ significantly between groups.nnnCONCLUSIONSnCatheter ablation of persistent/long-standing persistent AF with the phased RF ablation system is effective with greater reduction of AF compared with MM. More intense anticoagulation strategies, careful attention to catheter placement relative to the pulmonary vein ostia, and elimination of electrode interaction are expected to reduce the risk of stroke, pulmonary vein stenosis, and asymptomatic cerebral emboli.

Alternative Site Pacing: It's Time to Define Terms

Although alternative site pacing to improve left ventricular function was discussed in the 1980s, the technical applications occurred early in this decade. Barin and co-workers reported on the efficacy and safety of right ventricular outflow tract (RVOT) pacing in 1991.^ That same year, Karpawich et al.^ introduced the feasihility of direct septal His-Purkinje pacing. At the NASPE meeting in 1992, DeCock et al.- presented an abstract suggesting that pacing the RVOT conferred hemodynamic benefits with an overall increase in cardiac index of 17% compared with standard apical lead placement. These initial studies have generated a great deal of interest in investigating the potential hemodynamic advantages of pacing alternative sites in the left and right ventricles to improve cardiac performance. Reflecting this research activity, no less than 85 abstracts on alternative site and multisite pacing were presented at the recent NASPE and Cardiostim sessions. The terms septal. right ventricuhr outflow tract, and outflow septum have all been used to describe sites of right ventricular lead placement apart from the apex. However, these terms are perhaps too generalized to permit a comparison of the benefits of any one site over another. The normal right ventricle is not a homogeneous anatomical structure. It is divided into posteroinferior inlet (sinus), heavily trabeculated body, and relatively smooth anterosuperior outflow (infundibnlum) portions. The body and outflow are separated by a semicircular arch of four distinct but interconnecting muscle biuidles (parietal band, infundibular septum, septal band, and moderator band).

Clinical results of an advanced SVT detection enhancement algorithm

Introduction: Supraventricular tachycardia (SVT) has many characteristics that are similar to ventricular tachycardia (VT). This presents a significant challenge for the SVT‐detection algorithms of an implantable cardioverter defibrillator (ICD). A newly developed ICD, which utilizes a Vector Timing and Correlation algorithm as well as interval‐based conventional SVT discrimination algorithms (Rhythm ID™), was evaluated in this study.

Acute Hemodynamic Effects of Atrial Pacing with Cardiac Resynchronization Therapy

Background: Chronotropic incompetence is common among patients with advanced heart failure (HF), thus atrial pacing (AP) is frequently utilized in this population. The hemodynamic effects of AP during cardiac resynchronization therapy (CRT) have not been well studied.

Experience with a Cosmetic Approach to Device Implantation

GIUDICI, M.C.: Experience with a Cosmetic Approach to Device Implantation. As more young patients are having device implantations, we need to be more concerned with appearance and function. Over a 20‐ month period pacemakers and defibrillators were implanted in 14 women (mean age 49 years) using a two‐incision technique that leaves no visible scars on the chest.

Mapping the coronary sinus and great cardiac vein

GIUDICI, M., et al.: Mapping the Coronary Sinus and Great Cardiac Vein. The purpose of this study was to develop a better understanding of the pacing and sensing characteristics of electrodes placed in the proximal cardiac veins. A detailed mapping of the coronary sinus (CS) and great cardiac vein (GCV) was done on 25 patients with normal sinus rhythm using a deflectable electrophysiological catheter. Intrinsic bipolar electrograms and atrial and ventricular pacing voltage thresholds were measured. For measurement purposes, the GCV and the CS were each subdivided into distal (D), middle (M), and proximal (P) regions, for a total of six test locations. Within the CS and GCV, the average atrial pacing threshold was always lower (P < 0.05) than the ventricle with an average ventricular to atrial ratio > 5, except for the GCV‐D. The average atrial threshold in the CS and GCV ranged from 0.2– to 1.0‐V higher than in the atrial appendage. Diaphragmatic pacing was observed in three patients. Atrial signal amplitude was greatest in the CS‐M, CS‐D, and GCV‐P and smaller in the CS‐P, GCV‐M, and GCV‐D. Electrode spacing did not significantly affect P wave amplitude, while narrower electrode spacing attenuated R wave amplitude. The average P:R ratio was highest with 5‐mm‐spaced electrodes compared to wider spaced pairs. The P:R ratio in the CS was higher (P < 0.05) than in all positions of the GVC. It is possible to pace the atrium independent of the ventricle at reasonably low thresholds and to detect atrial depolarization without undue cross‐talk or noise using closely spaced bipolar electrode pairs. The areas of the proximal, middle, and distal CS produced the best combination of pacing and sensing parameters.