Tiziana Giovannini

Relationship between age and anterograde refractoriness of the accessory pathway in Wolff-Parkinson-White patients.

In 22 patients (age range 13-40 years) with Wolff-Parkinson-White ECG pattern without evidence of associated cardiomyopathy we measured the anterograde effective refractory period of the accessory pathway (ERP-AP) by extrastimulus method (at twice diastolic threshold) during atrial pacing (100/min). The ERP-AP range was 220-480 ms. There was a significant direct correlation between age and ERP-AP (r = 0.50, p less than 0.01). An ERP-AP less than or equal to 250 ms was found in 4 patients (age less than or equal to 23 years). This is noteworthy in the light of reports that, over the years: (1) typical Wolff-Parkinson-White ECG signs can disappear and (2) the frequency of tachycardic episodes decreases. Our data suggest a lower risk of high ventricular rates during atrial fibrillation with increasing age.

Wavelength Index at Three Atrial Sites in Patients with Paroxysmal Atrial Fibrillation

PADELETTI, L., et.al.: Wavelength Index at Three Atrial Sites in Patients with Paroxysmal Atrial Fibrillation. The purpose of this study was to evaluate the wavelength index (WLI) at three atrial sites in a group of 23 patients with recurrent episodes of lone paroxysmal atrial fibrillation (LPAF) and a control group (n = 20). All patients underwent programmed atrial stimulation (paced cycle length = 600 ms) at high, medium, and low lateral right atrial wall. P wave duration, sinus cycle length, and corrected sinus node recovery time were not significantly different between the two study groups. WLI was calculated according to the following formulas: atrial effective refractory period (AERP)/duration of atrial extrastimulus electrogram (A2) or AERP/A2+ atrial latency; and atrial functional refractory period (AFRP)/A2. WLI was significantly shorter in LPAF than in the control group at each of the paced atrial sites independently of the formula used. Duration of premature atrial electrogram appeared to play the major role in determining the difference in WLI between patients with paroxysmal atrial fibrillation and the control group.

Effects of Training on the Electrophysiologic Properties of Atrium and Accessory Pathway in Athletes with Wolff-Parkinson-White Syndrome

Twenty-two subjects with Wolff-Parkinson-White (WPW) electrocardiographic pattern performing agonistic physical activity were referred to our laboratory to assess arrhythmogenic risk (group 1). This allowed us to evaluate a less known aspect, namely that of effects of training on the electrophysiologic properties of the atrium and accessory pathway. This was done utilizing a control group of 10 WPW patients who did not perform agonistic physical activity (group 2). All subjects were symptom free, and without signs of associated cardiopathy if we exclude 1 patient of group 1, who presented moderate mitral valve prolapse. Group 1 patients showed significantly higher mean values for basic cycle length (p less than 0.001), atrial effective (p less than 0.04) and functional (p less than 0.02) refractory period, and anterograde effective refractory period of the accessory pathway (p less than 0.02). The different behavior observed in group 1 patients could be explained considering the known influence of training on the equilibrium of the autonomic nervous system. Moreover, it is noteworthy that the two groups did not differ for inducibility of atrial fibrillation (AF). This should be taken into account considering the importance of AF in WPW. In conclusion, our study does not demonstrate any negative electrophysiologic effects of training in patients with WPW.

Interlead anatomic and electrical distance predict outcome in CRT patients

BACKGROUND The implantation strategy appears to play a pivotal role in determining response to cardiac resynchronization therapy (CRT). OBJECTIVE The aim of our study was to determine the association between anatomic and electrical interlead distance and clinical outcome after CRT implantation. METHODS We included 216 first-time CRT recipients with left bundle branch block and sinus rhythm. On implantation, the electrical interlead distance (EID), defined as the time interval between spontaneous peak R waves detected at the right ventricular (RV) and left ventricular (LV) pacing sites, was measured. The anatomic distance between the RV and LV lead tips was determined on chest radiographs. RESULTS The mean EID was 74 ± 41 ms, and the mean horizontal corrected interlead distance (HCID) was 125 ± 73 mm. After 12 months, 87 patients (40%) displayed an improvement in their clinical composite score. The cutoff values that best predicted an improved clinical status were as follows: 84 ms for EID (area under the curve 0.59; confidence interval [CI] 0.52-0.66; P = .026) and 90 mm for HCID (area under the curve 0.62; CI 0.55-0.69; P = .004). On multivariate analysis, only EID >84 ms (hazard ratio 0.36; CI 0.14-0.89; P = .028) and HCID >90 mm (hazard ratio 0.45; CI 0.23-0.90; P = .025) were significantly associated with the composite endpoint of death or cardiovascular hospitalization. In particular, the presence of both conditions (EID <84 ms and HCID <90 mm) was associated with the highest rate of events (log-rank test P = .002). CONCLUSIONS The interlead anatomic and electrical distance are strongly and independently associated with patient outcome after CRT implantation. The 2 measures show an additive predictive value. (CRT MORE: Cardiac Resynchronization Therapy Modular Registry; www.clinicaltrials.gov, unique identifier: NCT01573091.)

Magnitude of QRS duration reduction after biventricular pacing identifies responders to cardiac resynchronization therapy

BACKGROUND Several studies have investigated the association between native QRS duration (QRSd) or QRS narrowing and response to biventricular pacing. However, their results have been conflicting. The aim of our study was to determine the association between the relative change in QRS narrowing index (QI) and clinical outcome and prognosis in patients who undergo cardiac resynchronization therapy (CRT) implantation. METHODS AND RESULTS We included 311 patients in whom a CRT device was implanted in accordance with current guidelines for CRT. On implantation, the native QRS, the QRSd and the QI during CRT were measured. After 6months, 220 (71%) patients showed a 10% reduction in LVESV. The median [25th-75th] QI was 14.3% [7.2-21.4] and was significantly related to reverse remodeling (r=+0.22; 95%CI: 0.11-0.32, p=0.0001). The cut-off value of QI that best predicted LV reverse remodeling after 6months of CRT was 12.5% (sensitivity=63.6%, specificity=57.1%, area under the curve=0.633, p=0.0002). The time to the event death or cardiovascular hospitalization was significantly longer among patients with QI>12.5% (log-rank test, p=0.0155), with a hazard ratio (HR) of 0.3 [95%CI: 0.11-0.78]. In the multivariate regression model adjusted for baseline parameters, a 10% increment in QI (HR=0.61[0.44-0.83], p=0.002) remained significantly associated with CRT response. CONCLUSIONS Patients with a larger decrease in QRSd after CRT initiation showed greater echocardiographic reverse remodeling and better outcome from death or cardiovascular hospitalization. QI is an easy-to-measure variable that could be used to predict CRT response at the time of pacing site selection or pacing configuration programming.

Access to magnetic resonance imaging of patients with magnetic resonance-conditional pacemaker and implantable cardioverter-defibrillator systems: results from the Really ProMRI study

Aims The Really ProMRI study evaluates magnetic resonance imaging (MRI) access for patients with cardiac implantable electronic devices (CIEDs) as well as the performance of magnetic resonance (MR)-conditional leads when undergoing MRI. Methods and results Patients either with an MR-conditional pacemaker or implantable defibrillator (ICD) system or with at least a component (device or one or more leads) from an MR-conditional system, were asked to fill in a questionnaire when they were referred to a MR scan. The rate of prescription, denial, or execution of MR examinations was evaluated in a 1-year follow-up visit. In total, 555 patients [median age (interquartile range) 72.2 (62.2-78.6); 72% male] were enrolled, 49% (270) with a pacemaker, 51% (285) with an ICD system. Five-hundred and ten patients completed the follow-up period. A total of 37 MRI referrals were reported in 35 patients, with a consequent event rate of 7.0/100 patient-years (CI, 4.9-9.7). Fourteen were denied, while 23 [66%; (CI, 48-81%)] were performed. The number of patients with MR referrals was not statistically different between pacemaker and ICD groups (21 vs. 14; P = 0.178). The rate of scans performed was higher in the pacemaker subjects (19/23 vs. 4/14, P = 0.003), while it was similar between patients with or without a complete MR-conditional system (19/30 vs. 4/7, P = 0.606). Conclusion In this study, we reported a 7.0/100 patient-years event rate of MR prescriptions in CIED patients. Many examinations were denied, despite MR-conditional systems, especially in ICD patients. Regulatory and cultural changes are needed to allow wider access to MR imaging in CIED patients with MR-conditional systems.