Accessory pathway localization with probabilistic density maps generated by a mobile application: Assessment of a full pre-excitation net-vector method.

INTRODUCTION: Precise electrocardiographic localization of accessory pathways (AP) can be challenging. Seminal AP localization studies were limited by complexity of algorithms and sample size. We aimed to create a nonalgorithmic method for AP localization based on color-coded maps of AP distribution generated by a web-based application. METHODS: APs were categorized into 19 regions/types based on invasive electrophysiologic mapping. Preexcited QRS complexes were categorized into 6 types based on polarity and notch/slur. For each QRS type in each lead the distribution of APs was visualized on a gradient map. The principle of common set was used to combine the single lead maps to create the distribution map for AP with any combination of QRS types in several leads. For the validation phase, a separate cohort of APs was obtained. RESULTS: A total of 800 patients with overt APs were studied. The application used the exploratory data set of 553 consecutive APs and the corresponding QRS complexes to generate AP localization maps for any possible combination of QRS types in 12 leads. Optimized approach (on average 3 steps) for evaluation of preexcited electrcardiogram was developed. The area of maximum probability of AP localization was pinpointed by providing the QRS type for the subsequent leads. The exploratory data set was validated with the separate cohort of APs (n = 256); p = .23 for difference in AP distribution. CONCLUSIONS: In the largest data set of APs to-date, a novel probabilistic and semi-automatic approach to electrocardiographic localization of APs was highly predictive for anatomic localization.

Simultaneous Entrainment Response Assessment at Multiple Sites.

BACKGROUND: The entrainment response, defined as the difference between the postpacing interval and the tachycardia cycle length (TCL) recorded from a mapping catheter, allows to track down the components of the tachycardia loop. OBJECTIVES: The aim of this study was to evaluate if the postpacing interval measured simultaneously from multiple sites that are remote from the pacing site (PPIR) could be clinically useful in mapping re-entrant circuits. METHODS: Ninety-two episodes of entrainment response in 29 patients with different macro-re-entrant tachycardias were evaluated using a standardized entrainment protocol. The spatial distribution of different values of PPIR-TCL in a simulation and a computational model of an entrained re-entrant tachycardia was also analyzed. RESULTS: The PPIR exceeded TCL by more than 20 milliseconds only if both pacing and recording sites were outside the tachycardia circuit. The PPIR-TCL at in-circuit sites was always ≤20 milliseconds. Sites with negative PPIR-TCL values were found either outside or inside the tachycardia circuit. CONCLUSIONS: Assessment of entrainment response from catheters remote from the pacing site may enhance spatial mapping of the tachycardia circuit. The PPIR-TCL above 20 milliseconds has an excellent positive predictive value in identifying sites outside the tachycardia circuit.

Innovative Managed Care May Be Related to Improved Prognosis for Acute Myocardial Infarction Survivors.

BACKGROUND: Mortality following discharge in myocardial infarction survivors remains high. Therefore, we compared outcomes in myocardial infarction survivors participating and not participating in a novel, nationwide managed care program for myocardial infarction survivors in Poland. METHODS: We used public databases. We included all patients hospitalized due to acute myocardial infarction in Poland between October 1, 2017 and December 31, 2018. We excluded from the analysis all patients aged <18 years as well as those who died during hospitalization or within 10 days following discharge from hospital. All patients were prospectively followed. The primary end point was defined as death from any cause. RESULTS: The mean follow-up was 324.8±140.5 days (78 034.1 patient-years; 340.0±131.7 days in those who did not die during the observation). Participation in the managed care program was related to higher odds ratio of participating in cardiac rehabilitation (4.67 [95% CI, 4.44-4.88]), consultation with a cardiologist (7.32 [6.83-7.84]), implantable cardioverter-defibrillator (1.40 [1.22-1.61]), and cardiac resynchronization therapy with cardioverter-defibrillator implantation (1.57 [1.22-2.03]) but lower odds of emergency (0.88 [0.79-0.98]) and nonemergency percutaneous coronary intervention (0.88 [0.83-0.93]) and coronary artery bypass grafting (0.82 [0.71-0.94]) during the follow-up. One-year all-cause mortality was 4.4% among the program participants and 6.0% in matched nonparticipants. The end point consisting of all-cause death, myocardial infarction, or stroke occurred in 10.6% and 12.0% (P<0.01) of participants and nonparticipants respectively, whereas all-cause death or hospitalization for cardiovascular reasons in 42.2% and 47.9% (P<0.001) among participants and nonparticipants, respectively. The difference in outcomes between patients participating and not participating in the managed care program could be explained by improved access to cardiac rehabilitation, cardiac care, and cardiac procedures. CONCLUSIONS: Managed care following myocardial infarction may be related to improved prognosis as it may facilitate access to cardiac rehabilitation and may provide a higher standard of outpatient cardiac care.

Use of an exercise test to enhance sensing vector assessment and prevent inadequate subcutaneous implantable cardioverter-defibrillator discharges.

Subcutaneous implantable cardioverter-defibrillators are a modern alternative to classic cardioverter-defibrillators. Prior to implantation of the device, qualification based on assessment of the heart's specific rhythm shape during a resting electrocardiogram examination must be performed. In the presented case, a patient with a subcutaneous implantable cardioverter-defibrillator experienced numerous discharges during exercise. An exercise test was performed, which revealed a bundle branch block that appeared during exercise. The wide QRS complex was double- or triple-counted by the device, resulting in an inaccurate heart rate estimation and multiple discharges. Optimising the sensing vectors during exercise solved this problem.

[Application of spectral frequency analysis in atrial fibrillation mechanism assessment]. / Zastosowanie spektralnej analizy czestotliwosciowej do oceny podloza napadowego migotania przedsionków.

Recent studies have demonstrated spatio-temporal organisation in atrial fibrillation (AF), with a highest dominant frequencies (DF) at pulmonary veins ostia (PVo). We present a case of 58-year-old woman with AF evaluated by spectral frequency analysis. Simultaneous recordings at each veno-atrial junction and coronary sinus were obtained. Sequential fast Fourier transforms (FFT) of digitalized signals were performed. FFT profiles were analysed to determine DF. Low DF recorded at right inferior PVo suggested no contribution to AF process. Ablation of high DF PVo and low DF SVC with nonuniform anisotropic conduction resulted in AF termination and good clinical outcome in 1-year follow-up.