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Introduction. When using Lesion Size index (LSI) to guide catheter ablation, it is unclear what combination of power, contact force and time would be preferable to use and what LSI target value to aim for. This study aimed at identifying desirable ablation settings and LSI targets by using tissue impedance drop as indicator of lesion formation. Methods. Consecutive patients, undergoing their first left atrial (LA) catheter ablation for atrial fibrillation, with RF powers of 20, 30 and 40 W were enrolled. Tissue impedance, contact force (CF), Force Time Integral (FTI) and LSI values were continuously recorded during ablation and sampled at 100 Hz. Mean CF and Contact Force Variability (CFV) were calculated for every lesion. The effect of RF power, ablation time, CF and CFV on impedance drop and LSI were assessed. Results. A total of 3258 lesions were included in the analysis. For any target LSI value, use of higher RF powers translated into progressively higher impedance drops. The impact of lower CF and higher CFV on impedance drop was more relevant when using lower powers. Target LSI values corresponding to maximum impedance drop were identified depending on RF power, mean CF and CFV used. Conclusions. Even in the context of an LSI-guided ablation strategy, use of lower or higher powers might lead to different lesion sizes. Different LSI targets might be needed depending on the combination of RF power, CF and CFV used for ablation. Incorporating indicators of catheter stability, like CFV, in the LSI formula could improve the predictive value of LSI for lesion size. Studies with clinical outcomes are required to confirm the clinical relevance of these findings.

Atrial fibrillation (AF) is associated with increased risk of heart failure and premature death, and is often resistant to treatment. Animal models of pacing-induced AF indicate that AF-induced endothelial dysfunction, impaired coronary reserve, and myocardial remodelling are important in arrhythmia maintenance. However, human AF may reflect a subclinical cardiomyopathy, which persists after sinus rhythm (SR) restoration and provides a substrate for AF recurrence. To test this hypothesis, we investigated the effect of restoring SR by catheter ablation on left ventricular (LV) function and energetics.

Atrial fibrillation (AF) is associated with subclinical left ventricular (LV) dysfunction and overt heart failure, but causal relationships are incompletely defined. Both AF and LV dysfunction may be tissue-specific manifestations of an underlying subclinical cardiomyopathy.

Supplemental Digital Content is available in the text., Background: Lone atrial fibrillation (AF) may reflect a subclinical cardiomyopathy that persists after sinus rhythm (SR) restoration, providing a substrate for AF recurrence. To test this hypothesis, we investigated the effect of restoring SR by catheter ablation on left ventricular (LV) function and energetics in patients with AF but no significant comorbidities. Methods: Fifty-three patients with symptomatic paroxysmal or persistent AF and without significant valvular disease, uncontrolled hypertension, coronary artery disease, uncontrolled thyroid disease, systemic inflammatory disease, diabetes mellitus, or obstructive sleep apnea (ie, lone AF) undergoing ablation and 25 matched control subjects in SR were investigated. Magnetic resonance imaging quantified LV ejection fraction (LVEF), peak systolic circumferential strain (PSCS), and left atrial volumes and function, whereas phosphorus-31 magnetic resonance spectroscopy evaluated ventricular energetics (ratio of phosphocreatine to ATP). AF burden was determined before and after ablation by 7-day Holter monitoring; intermittent ECG event monitoring was also undertaken after ablation to investigate for asymptomatic AF recurrence. Results: Before ablation, both LV function and energetics were significantly impaired in patients compared with control subjects (LVEF, 61% [interquartile range (IQR), 52%–65%] versus 71% [IQR, 69%–73%], P

Objectives The goal of this study was to assess the contemporary and historical success rates of transvenous left ventricular (LV) lead placement for cardiac resynchronization therapy (CRT), their change over time, and the reasons for failure. Background In selected patients, CRT improves morbidity and mortality, but the placement of the LV lead can be technically challenging. Methods A literature search was used to identify all studies reporting success rates of LV lead placement for CRT via the coronary sinus (CS) route. A total of 164 studies were identified, and a meta-analysis was performed. Results The studies included 29,503 patients: 74% (95% confidence interval [CI]: 72% to 76%) were male; their mean age was 66 years (95% CI: 65 to 67); their mean New York Heart Association functional class was 2.8 (95% CI: 2.7 to 2.9); the mean LV ejection fraction was 26% (95% CI: 25% to 28%); and the mean QRS duration was 155 ms (95% CI: 150 to 160). The overall rate of failure of implantation of an LV lead was 3.6% (95% CI: 3.1 to 4.3). The rate of failure in studies commencing before 2005 was 5.4% (95% CI: 4.4% to 6.5%), and from 2005 onward it was 2.4% (95% CI: 1.9% to 3.1%; p < 0.001). Causes of failure (reported for 39% of failures) also changed over time. Failure to cannulate and navigate the CS decreased from 53% to 30% (p = 0.01), and the absence of any suitable, acceptable vein increased from 39% to 64% (p = 0.007). The proportion of leads in a lateral or posterolateral final position (reported for 26% of leads) increased from 66% to 82% (p = 0.004). Conclusions The reported rate of failure to place an LV lead via the CS has decreased steadily over time. A greater proportion of failures in recent studies are due to coronary venous anatomy that is unsuitable for this technique.