Contact versus Noncontact Mapping for Ablation of Ventricular Tachycardia in Patients with Previous Myocardial Infarction

Introduction: The aim of this study was to compare contact versus noncontact mapping for radiofrequency (RF) ablation of any sustained post-myocardial infarction (MI) ventricular tachycardia (VT).
Methods: Forty patients with tolerated VT post-MI were randomized to RF ablation with contact (group 1) or noncontact (group 2) mapping systems. In both groups ablation of tolerated VT was guided by VT activation map confirmed by concealed entrainment. When untolerated VTs were induced, ablation was performed in group 1 according to pace mapping starting from the scar border zone and in group 2 according to the VT activation map confirmed by pace mapping.
Results: No differences were seen between the groups in terms of acute success rate of clinical VT ablation (95% vs 100%, respectively; P = ns) and in the noninducibility of any VT at the end of the procedure (55% vs 85%, respectively; P = 0.08). Moreover, untolerated VTs were eliminated in 30% of group 1 versus 83.3% of group 2 patients (P < 0.05). The mean total procedural and fluoroscopy times were 236.4 ± 42.7 and 29.0 ± 7.8 minutes in group 1 and 144.5 ± 50.8 and 23.4 ± 5.8 minutes in group 2 (P < 0.001 and < 0.05, respectively). At a mean follow-up of 15.2 ± 6.7 months no differences were seen in VT recurrences between groups, but noninducibility at the end of the procedure was predictive of freedom from recurrences (P < 0.001).
Conclusion: Both systems are useful for ablation of tolerated VT. Noncontact mapping is more effective for ablation of untolerated VT and allows the reduction of procedural and fluoroscopy times. Noninducibility at the end of the procedure seems predictive of freedom from recurrences during follow-up.     

Italian Multicenter Study on a Single Lead VDD Pacing System Using a Narrow Atrial Dipole Spacing

Since November 1988, 514 patients with advanced atrioventricular (AV) block and normal sinoatrial function have received the single lead VDD pacing system Twinal 30 Lem/CCS in 30 Italian centers. At implantation, particular attention was paid to the correct positioning of the atrial dipole in the mid- to mid-high right atrium and to the atrial electrogram characteristics. The follow-up included a chest X ray, to be performed before discharge of the patient from the hospital, telemetric evaluations of the endoatrial potential, provocative tests for interferences by myopotentials, 24-hour ambulatory EGG recordings, and where possible, exercise stress tests. The mean follow-up duration was 15.2 months, ranging from 1 to 42 months. A very low percentage of chronic atrial fibrillation, loss of atrial sensing, and system replacement was reported, most of the patients (93.5%) being paced in VDD mode. All investigations indicated an excellent overall system performance, stable AV synchrony, and infrequent myopotential interference, and a low complication rate throughout the follow-up period.     

Long-Term Reliability of Single Lead Atrial Synchronous Pacing Systems Using Closely Spaced Atrial Dipoles: Five-Year Experience

To assess the long-term capability of single atrioven ticular (AV) lead VDD pacing systems using close atrial dipoles to assure reliable atrial guided pacing, the safety and efficacy of 86 VDD units implanted in 73 patients at a single center since November 1988 was reviewed. All patients suffered from advanced AV block with normal sinoatrial function. Sixty five patients received a LEM/CCS Twinal 30/30S system, four patients received a Vitatron-Saphir system, and four patients received a Medtronic Thera VDR 8348 system. All patients underwent provocative tests in search of myopotential interference, and Holter recordings; in a group of patients who underwent pacemaker replacement a comparison was made between implant and replacement measurements. The mean follow-up duration was 27.3 months. A high percentage of successfully VDD paced patients and a low incidence of pacemaker malfunction, regularly solved by pacemaker reprogramming, was reported. Atrial signal amplitudes comparable to those measured at implant were found at replacement in all patients. These data support the long-term reliability of single AV lead VDD pacing systems with closely spaced atrial dipoles, as well as stable atrial sensing by floating bipolar atrial electrodes and effective atrial synchronous ventricular pacing over time.     

A New Single Lead VDD Pacing System

PERCOCO, G.F., ET AL.: A New Single Lead VDD Pacing System. In 24 patients with advanced heart block and normal sinus node function, a new single lead VDD pacing system was implanted. At implantation, the endoatrial, bipolar electrogram was recorded in all patients. The lead position was checked by means of chest X-ray. At discharge and after 1, 3, and 6 months, testing for myopotential inhibition, telemetric evaluation of the endoatrial potential, and Holter recordings were made. After discharge, 18 patients performed two cardiopulmonary exercise tests at two different rate-matched AV intervals. All investigations showed good AV synchrony and a lack of interferences by myopotentials. The maximum rate-matched AV interval provided a significantly improved exercise capacity, which was more evident in patients with signs of myocardial failure.