Functional mapping to reveal slow conduction and substrate progression in atrial fibrillation.

AIMS: The aim of our study was to analyse the response to short-coupled atrial extrastimuli to identify areas of hidden slow conduction (HSC) and their relationship with the atrial fibrillation (AF) phenotype. METHODS AND RESULTS: Twenty consecutive patients with paroxysmal AF and persistent AF (10:10) underwent the first pulmonary vein isolation procedure. Triple short-coupled extrastimuli were delivered in sinus rhythm (SR), and the evoked response was analysed: sites exhibiting double or highly fragmented electrograms (EGM) were defined as positive for HSC (HSC+). The delta of the duration of the bipolar EGM was analysed, and bipolar EGM duration maps were built. High-density maps were acquired using a multipolar catheter during AF, SR, and paced rhythm. Spatial co-localization of HSC+ and complex fractionated atrial EGMs (CFAE) during AF was evaluated. Persistent AF showed a higher number and percentage of HSC+ than paroxysmal AF (13.9% vs. 3.3%, P < 0.001). The delta of EGM duration was 53 ± 22 ms for HSC+ compared with 13 ± 11 (10) ms in sites with negative HSC (HSC-) (P < 0.001). The number and density of HSC+ were lower than CFAE during AF (19 vs. 56 per map, P < 0.001). The reproducibility and distribution of HSC+ in repeated maps were superior to CFAE (P = 0.19 vs. P < 0.001). Sites with negative and positive responses showed a similar bipolar voltage in the preceding sinus beat (1.65 ± 1.34 and 1.48 ± 1.47 mV, P = 0.12). CONCLUSION: Functional mapping identifies more discrete and reproducible abnormal substrates than mapping during AF. The HSC+ sites in response to triple extrastimuli are more frequent in persistent AF than in paroxysmal AF.

What eyes do not see the heart does not grieve over? The role of intracoronary imaging in acute myocardial infarction: a case report.

Background: The evaluation of a three-dimensional structure with a two-dimensional imaging technique makes intracoronary diagnostic techniques essential, especially in the setting of acute myocardial infarction (AMI) when no apparent coronary lesions are detected. Expert consensus recommend their use in certain scenarios such as angiographically ambiguous disease and identification of the culprit lesion. Although both intravascular ultrasound and optical coherence tomography (OCT) allow the characterization of the atherosclerotic plaque and assess the immediate and long-term results of stent implantation, they have their own benefits and limitations that make them ideal for different types of coronary lesions. Case summary: We present the case of a lateral ST-elevation myocardial infarction with no evident coronary lesions in angiography, in which OCT not only allowed us to confirm a diagonal branch occlusion, but it also became crucial to locate the occlusion point and to guide the procedure, allowing complete revascularization of the culprit lesion that otherwise could have been missed. Discussion: To know the actual limitations of conventional coronary angiography to adequately assess coronary disease, intracoronary diagnostic techniques are key to evaluate the underlying mechanisms of the event, especially in the setting of AMI when no clear culprit lesion has been identified. They can be of great value to locate and revascularize acute occlusions that could go unnoticed on the angiogram, guiding the revascularization and stent implantation and, therefore, preventing myocardial injury that could become irreversible when coronary disease is not treated promptly.

Reproducibility of bolus versus continuous thermodilution for assessment of coronary microvascular function in patients with ANOCA.

BACKGROUND: A bolus thermodilution-derived index of microcirculatory resistance (IMR) has emerged as the standard for assessing coronary microvascular dysfunction (CMD). Continuous thermodilution has recently been introduced as a tool to quantify absolute coronary flow and microvascular resistance directly. Microvascular resistance reserve (MRR) derived from continuous thermodilution has been proposed as a novel metric of microvascular function, which is independent of epicardial stenoses and myocardial mass. AIMS: We aimed to assess the reproducibility of bolus and continuous thermodilution in assessing coronary microvascular function. METHODS: Patients with angina and non-obstructive coronary artery disease (ANOCA) at angiography were prospectively enrolled. Bolus and continuous intracoronary thermodilution measurements were obtained in duplicate in the left anterior descending artery (LAD). Patients were randomly assigned in a 1:1 ratio to undergo either bolus thermodilution first or continuous thermodilution first. RESULTS: A total of 102 patients were enrolled. The mean fractional flow reserve (FFR) was 0.86±0.06. Coronary flow reserve (CFR) calculated with continuous thermodilution (CFRcont) was significantly lower than bolus thermodilution-derived CFR (CFRbolus; 2.63±0.65 vs 3.29±1.17; p<0.001). CFRcont showed a higher reproducibility than CFRbolus (variability: 12.7±10.4% continuous vs 31.26±24.85% bolus; p<0.001). MRR showed a higher reproducibility than IMR (variability 12.4±10.1% continuous vs 24.2±19.3% bolus; p<0.001). No correlation was found between MRR and IMR (r=0.1, 95% confidence interval: -0.09 to 0.29; p=0.305). CONCLUSIONS: In the assessment of coronary microvascular function, continuous thermodilution demonstrated significantly less variability on repeated measurements than bolus thermodilution.

Litotricia coronaria en lesión aortoostial gravemente calcificada no dilatable con balón de corte / Coronary lithotripsy in a severely calcified, cutting-balloon undilatable aorto-ostial lesion

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