After LVAD placement, there is a significant rise in the incidence of de novo MVT. By contrast, the incidence of PVT/VF was unaffected by LVAD placement.

In comparison to exercise and atropine, isoproterenol is associated with much less QT shortening for a given increase in HR and, therefore, greater absolute QT intervals. Our findings demonstrate that autonomic conditions directly affect the ventricular myocardium of healthy subjects, causing differences in QT that are independent of HR.

Background - The limited effectiveness of endocardial catheter ablation (CA) for persistent and long-standing persistent atrial fibrillation (Ps/LSP-AF) treatment led to the development of a minimally-invasive epicardial/endocardial ablation approach (Hybrid Convergent) to achieve a more comprehensive lesion set with durable transmural lesions. The multi-center randomized controlled CONVERGE trial (NCT01984346) evaluated the safety of Hybrid Convergent and compared its effectiveness to CA for Ps/LSP-AF treatment. Methods - One-hundred fifty-three patients were randomized 2:1 to Hybrid Convergent vs. CA. Primary effectiveness was freedom from AF/AFL/AT absent new/increased dosage of previously failed/intolerant class I/III anti-arrhythmic drugs (AADs) through 12-months. Primary safety was major adverse events through 30 days. CONVERGE permitted left atrium size up to 6cm and imposed no limits on AF duration, making it the only ablation trial to substantially include LSP-AF i.e. 42% patients with LSP-AF. Results - Of 149 evaluable patients at 12 months, primary effectiveness was achieved in 67.7% (67/99) patients with Hybrid Convergent and 50.0% (25/50) with CA (p=0.036) on/off previously failed AADs and in 53.5% (53/99) versus 32.0% (16/50) (p=0.0128) respectively off AADs. At 18-months using 7-day Holter, 74.0% (53/72) Hybrid Convergent and 55% (23/42) CA patients experienced ≥90% AF burden reduction. A total of 2.9% (3/102) patients had primary safety events within 7 days, and 4.9% (5/102) between 8-30 days post-procedure. No deaths, cardiac perforations or atrioesophageal fistulas occurred. All but one primary safety event resolved. Conclusions - The Hybrid Convergent procedure has superior effectiveness compared to the CA for the treatment of Ps/LSP-AF.

Methods to correct the QT interval for heart rate are often in disagreement and may be further confounded by changes in autonomic state. This can be problematic when trying to distinguish the changes in QT interval by either drug-induced delayed repolarization or from autonomic-mediated physiological responses. Assessment of the canine dynamic QT-RR interval relationship was visualized by novel programming of the dynamic beat-to-beat confluence of data or "clouds". To represent the nonuniformity of the clouds, a bootstrap sampling method that computes the mathematical center of the uncorrected beat-to-beat QT value (QTbtb) with upper 95% confidence bounds was adopted and compared with corrected QT (QTc) using standard correction factors. Nitroprusside-induced reflex tachycardia reduced QTbtb by 43 ms, whereas an increase of 55 and 16 ms was obtained using the Bazett (QTcB) and Fridericia (QTcF) formulae, respectively. Phenylephrineinduced reflex bradycardia increased QTbtb by 3 ms but decreased QTcB by 20 ms and QTcF by 12 ms. Delayed repolarization with E-4031 (1-[2-(6-methyl-2-pyridyl)ethyl]-4-methylsulfonylaminobenzoyl)-piperidine), an inhibitor of rectifier potassium current, increased QTbtb by 26 ms but QT prolongation calculations using QTcF and QTcB were between 12 and 52% less, respectively, when small decreases in heart rate (5-8 beats per minute) were apparent. Dynamic assessment of beatto-beat data, using the bootstrap method, allows quantification of QT interval changes under varying conditions of heart rate, autonomic tone, and direct repolarization that may not be distinguishable with use of standard correction factors.Ventricular repolarization, as reflected in the surface QT interval, can be affected by drugs as well as autonomic state, both directly and via their effects on heart rate (HR). Methods to normalize the QT interval for changes in heart rate have been described since early last century (Bazett, 1920;Fridericia, 1920). Bazett noted in his original proposal that the K from his correction factor of K͌RR varied when the vagus nerve was sectioned or stimulated. Simonsen et al. (1962) demonstrated discrepancies in eight different correction factors when modeling the HR-QT interval relationship on the same dataset. Browne et al. (1982) later showed that a 75-ms shortening of the absolute QT interval with atropine during fixed rate atrial pacing was interpreted as a 43-ms prolongation using the Bazett correction. This 118-ms difference suggests that Bazett's formula "undercorrected" the QT interval for the increase in HR observed during vagal inhibition. Similarly, patients receiving propranolol or the atropine/propranolol combination had differences in the corrected QT (QTc) interpretation of approximately 30 and 60 ms, respectively.Prolongation of the QT interval has been associated with an increased incidence of the fatal ventricular tachyarrhythmia, Torsade de Pointe. Since many drugs that have been removed from the marketplace due to an increased occurrence of Torsade de Pointe p...

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