Delayed FDG PET-CT imaging should be considered at least in patients with negative 1-hour scan and founded suspicion of pacing lead infection.

Background - Low radiofrequency (RF) powers are commonly used on the posterior wall of the left atrium (LA) for atrial fibrillation (AF) ablation to prevent esophageal damage. Compared with higher powers, they require longer ablation durations to achieve a target lesion size index (LSI). Esophageal heating during ablation is the result of a time-dependent process of conductive heating produced by nearby RF delivery. This randomized study was conducted to compare risk of esophageal heating and acute procedure success of different LSI-guided ablation protocols combining higher or lower RF power and different target LSI values. Methods - Eighty consecutive patients were prospectively enrolled and randomized to one of 4 combinations of RF power and target LSI for ablation on the LA posterior wall (20W/LSI 4, 20W/LSI 5, 40W/LSI 4 and 40W/LSI 5). The primary endpoint of the study was the occurrence and number of esophageal temperature alerts (ETAs) per patient during ablation. Acute indicators of procedure success were considered as secondary end-points. Long term follow-up data were also collected for all patients. Results - Esophageal temperature alerts (ETAs) occurred in a similar proportion of patients in all groups. Significantly shorter RF durations were required to achieve the target LSI in the 40W groups. Less than 50% of the RF lesions reached the target LSI of 5 when using 20W despite a longer RF duration. A lower rate of first-pass Pulmonary Vein Isolation and a higher rate of acute Pulmonary Vein Reconnection were recorded in the group 20W/LSI 5. A lower AF recurrence rate was observed in the 40W groups compared to the 20W groups at 29 months follow-up. Conclusions - When guided by LSI, posterior wall ablation with 40W is associated with a similar rate of ETAs and a lower AF recurrence rate at follow-up if compared to 20W. These data will provide a basis to plan future randomized trials.

In our meta-analysis of observational studies, patients who have been treated in higher volume centres have a lower probability of minor complications and death at 30 days regardless of the infection rate, length of lead duration, type of device, and type of extraction.

The objective of the study was to better characterize the clinical phenotype associated with the A8344G "MERRF" mutation of mitochondrial DNA. Fifteen mutated patients were extensively investigated. The frequency of main clinical features was: exercise intolerance and/or muscle weakness 67 %, respiratory involvement 67 %, lactic acidosis 67 %, cardiac abnormalities 53 %, peripheral neuropathy 47 %, myoclonus 40 %, epilepsy 40 %, ataxia 13 %. A restrictive respiratory insufficiency requiring ventilatory support was observed in about half of our patients. One patient developed a severe and rapidly progressive cardiomyopathy requiring cardioverter-defibrillator implantation. Five patients died of overwhelming, intractable lactic acidosis. Serial muscle MRIs identified a consistent pattern of muscle involvement and progression. Cardiac MRI showed non-ischemic late gadolinium enhancement in the left ventricle inferolateral part as early sign of myocardial involvement. Brain spectroscopy demonstrated increased peak of choline and reduction of N-acetylaspartate. Lactate was never detected in brain areas, while it could be documented in ventricles. We confirm that muscle involvement is the most frequent clinical feature associated with A8443G mutation. In contrast with previous reports, however, about half of our patients did not develop signs of CNS involvement even in later stages of the disease. The difference may be related to the infrequent investigation of A8344G mutation in 'pure' mitochondrial myo-cardiomyopathy, representing a bias and a possible cause of syndrome's underestimation. Our study highlights the importance of lactic acidosis and respiratory muscle insufficiency as critical prognostic factors. Muscle and cardiac MRI and brain spectroscopy may be useful tools in diagnosis and follow-up of MERRF.