The impact of myocardial viability on the clinical outcome of cardiac resynchronization therapy.

INTRODUCTION: Around 30% of patients do not respond to cardiac resynchronization therapy (CRT). Nonischemic cardiomyopathy has been identified as an independent predictor of response to CRT, probably due to the absence of compact scar. METHODS AND RESULTS: The relationship between cardiac scar, ischemia, and hibernation (both at the left-ventricular pacing site and as a total burden) and response to CRT was studied in patients with ischemic cardiomyopathy using the perfusion-viability positron emission tomography (PET) test. Sixty-six patients with ischemic cardiomyopathy and traditional criteria for CRT were included. All patients underwent PET scan prior to CRT. Using PET, the amount and location of scarred, ischemic, and hibernating myocardium were characterized. No revascularization was indicated. Responders were defined by an improvement of left-ventricular ejection fraction (LVEF) >or= 5% and/or New York Heart Association (NYHA) class >or= 1 degree. During a mean follow-up of 26.2 +/- 22.2 months, there was a significant improvement in NYHA class and reverse remodeling in patients with the LV lead inserted remotely from the scar. However, reverse remodeling of a similar degree was present also in patients with extensive scarring including the lateral wall. The presence of ischemia, hibernation, or nontransmural scar at the pacing-site did not significantly modify the outcome of CRT as compared with viable myocardium. There were only 38% of CRT-nonresponders. Neither the extent of scar, ischemia, hibernation, or viability predicted outcome or mortality. Twenty patients died during the follow-up, one patient underwent heart transplant. CONCLUSIONS: At follow-up, response to CRT is observed regardless of the presence of extensive scarring. Left ventricular (LV) pacing at sites with ischemia, hibernation, or nontransmural scar does not appear to modify the effect of CRT as compared to viable tissue.

Remote magnetic navigation: human experience in pulmonary vein ablation.

OBJECTIVES: We aimed at assessing the feasibility and efficacy of remote magnetic navigation (MN) and ablation in patients with atrial fibrillation (AF). BACKGROUND: This novel MN system could facilitate standardization of the procedures, reducing the importance of the operator skill. METHODS: After becoming familiar with the system in 48 previous patients, 45 consecutive patients with AF were considered for ablation using the Niobe II remote magnetic system (Stereotaxis, St. Louis, Missouri) in a stepwise approach: circumferential pulmonary vein ablation (CPVA), pulmonary vein antrum isolation (PVAI), and, if failed, PVAI using the conventional approach. Remote navigation was done using the coordinate or the wand approach. Ablation end point was electrical disconnection of the pulmonary veins (PVs). RESULTS: Using the coordinate approach, the target location was reached in only 60% of the sites, whereas by using the wand approach 100% of the sites could be reached. After step 2 ablation, only 1 PV in 4 patients (8%) could be electrically isolated. Charring on the ablation catheter tip was seen in 15 (33%) of the cases. In 23 patients, all PVs were isolated with the conventional thermocool catheter, and in 22 patients only the right PVs were isolated with the conventional catheter. After a mean follow-up period of 11 +/- 2 months, recurrence was seen in 5 patients (22%) with complete PVAI and in 20 patients (90%) with incomplete PVAI. CONCLUSIONS: Remote navigation using a magnetic system is a feasible technique. With the present catheter technology, effective lesions cannot be achieved in most cases. This appears to impact the cure rate of AF patients.

Pulmonary vein total occlusion following catheter ablation for atrial fibrillation: clinical implications after long-term follow-up.

OBJECTIVES: We present the clinical course and management outcomes of patients with total pulmonary vein occlusion (PVO). BACKGROUND: Pulmonary vein occlusion is a rare complication that can develop after radiofrequency catheter ablation (RFA) of atrial fibrillation (AF). The long term follow-up data of patients diagnosed with PVO are minimal. METHODS: Data from 18 patients with complete occlusion of at least one pulmonary vein (PV) were prospectively collected. All patients underwent RFA for AF using different strategies between September 1999 and May 2004. Pulmonary vein occlusion was diagnosed using computed tomography (CT) and later confirmed by angiography when intervention was warranted. Lung perfusion scans were performed on all patients before and after intervention. The percent stenoses of the veins draining each independent lung were added together to yield an average cumulative stenosis of the vascular cross-sectional area draining the affected lung (cumulative stenosis index [CSI]). RESULTS: The patients' symptoms had a positive correlation with the CSI (r = 0.843, p < 0.05) and a negative one with the lung perfusion (r = -0.667, p < 0.05). A CSI > or =75% correlated well with low lung perfusion (<25%; r = -0.854, p < 0.01). Patients with a CSI > or =75% appeared to improve mostly when early (r = -0.497) and repeat dilation/stenting (r = 0.0765) were performed. CONCLUSIONS: Patients with single PVO are mostly asymptomatic and should undergo routine imaging. On the other hand, patients with concomitant ipsilateral PV stenosis/PVO and a CSI > or =75% require early and, when necessary, repeated pulmonary interventions for restoration of pulmonary flow and prevention of associated lung disease.