Is 7-day event triggered ECG recording equivalent to 7-day Holter ECG recording for atrial fibrillation screening?

OBJECTIVE: Prolonged ECG monitoring is standard for atrial fibrillation (AF) screening. This study investigated whether 7-day event triggered (tECG) ECG recording is equivalent to 7-day continuous Holter (cECG) ECG recording for AF screening. DESIGN: Both a cECG (Lifecard CF) and a tECG (R.Test Evolution 3) were simultaneously worn for 7 days by patients with known or suspected paroxysmal AF. RESULTS: In 100 corresponding recordings, median effective duration of monitoring was 165 h (range 10-170 h) for cECG and 137 h (0-169 h) for tECG (p<0.001). Median number and total duration of arrhythmias (AF, atrial flutter or atrial tachycardia) of ≥30 s duration recorded by cECG were 10 (1-428) and 1030 min (≤1-10,020), respectively. An arrhythmia was recorded in 42 cECGs (42%) versus 37 tECGs (37%, p=0.56). Triggered ECG failed to record an arrhythmia in cECG positive cases because of interrupted monitoring in four cases and because of recording failure in one case. Sensitivity, specificity, and positive and negative predictive values of tECG therefore were 88%, 100%, 100%, and 92%, respectively. Quantitative cECG analysis required a median of 20 min (3-205 min) and qualitative tECG analysis 4 min (1-20 min; p<0.001). Skin irritation was a frequent side effect (42%) resulting in premature removal of devices in 16% of patients. CONCLUSION: Sensitivity of tECG for AF screening as compared to cECG is lower, mainly because of shorter effective monitoring duration. Qualitative tECG analysis is less time consuming than quantitative cECG analysis. Skin irritation is a frequent side effect and reason for premature device removal.

Dual-loop circuits in postoperative atrial macro re-entrant tachycardias.

BACKGROUND: Patients may develop dual-loop re-entrant atrial arrhythmias late after open-heart surgery, and mapping and catheter ablation remain challenging despite computer-assisted mapping techniques. OBJECTIVES: The purpose of the study was to demonstrate the prevalence and characteristics of dual-loop re-entrant arrhythmias, and to define the optimal mapping and ablation strategy. METHODS: 40 consecutive patients (mean (SD) age 52 (12) years) with intra-atrial re-entrant tachycardia (IART) after open-heart surgery (with an incision of the right atrial free wall) were studied. Dual-loop IART was defined as the presence of two simultaneous atrial circuits. After an abrupt tachycardia change during radiofrequency ablation, electrical disconnection of the targeted re-entry isthmus from the remaining circuit was demonstrated by entrainment mapping. Furthermore, the second circuit loop was localised using electroanatomical mapping and/or entrainment mapping. RESULTS: Dual-loop IART was demonstrated in eight (20%, 5 patients with congenital heart disease, 3 with acquired heart disease) patients. Dual-loop IART included an isthmus-dependant atrial flutter combined with a re-entry related to the atriotomy scar. The diagnosis of dual-loop IART required the comparison of entrainment mapping before and after tachycardia modification. Overall, 35 patients had successful radiofrequency ablation (88%). Success rates were lower in patients with dual-loop IART than in patients without dual-loop IART. Ablation failures in three patients with dual-loop IART were related to the inability to properly transect the second tachycardia isthmus in the right atrial free wall. CONCLUSIONS: Dual-loop IART is relatively common after heart surgery involving a right atriotomy. Abrupt tachycardia change and specific entrainment mapping manoeuvres demonstrate these circuits. Electroanatomical mapping appears to be important to assist catheter ablation of periatriotomy circuits.

A novel SCN5A mutation, F1344S, identified in a patient with Brugada syndrome and fever-induced ventricular fibrillation.

OBJECTIVE: Brugada syndrome (BS) is an inherited electrical cardiac disorder characterized by right bundle branch block pattern and ST segment elevation in leads V1 to V3 on surface electrocardiogram that can potentially lead to malignant ventricular tachycardia and sudden cardiac death. About 20% of patients have mutations in the only so far identified gene, SCN5A, which encodes the alpha-subunit of the human cardiac voltage-dependent sodium channel (hNa(v)1.5). Fever has been shown to unmask or trigger the BS phenotype, but the associated molecular and the biophysical mechanisms are still poorly understood. We report on the identification and biophysical characterization of a novel heterozygous missense mutation in SCN5A, F1344S, in a 42-year-old male patient showing the BS phenotype leading to ventricular fibrillation during fever. METHODS: The mutation was reproduced in vitro using site-directed mutagenesis and characterized using the patch clamp technique in the whole-cell configuration. RESULTS: The biophysical characterization of the channels carrying the F1344S mutation revealed a 10 mV mid-point shift of the G/V curve toward more positive voltages during activation. Raising the temperature to 40.5 degrees C further shifted the mid-point activation by 18 mV and significantly changed the slope factor in Na(v)1.5/F1344S mutant channels from -6.49 to -10.27 mV. CONCLUSIONS: Our findings indicate for the first time that the shift in activation and change in the slope factor at a higher temperature mimicking fever could reduce sodium currents' amplitude and trigger the manifestation of the BS phenotype.

Irrigated-tip catheter ablation of intraatrial reentrant tachycardia in patients late after surgery of congenital heart disease.

OBJECTIVES: The aim of this study was to evaluate irrigated-tip catheter for ablation of intraatrial reentrant tachycardias late after surgical repair of congenital heart disease. BACKGROUND: In congenital heart disease patients, the right atrium can be markedly enlarged with areas of low blood flow. Radiofrequency (RF) lesion creation may be hampered by insufficient electrode cooling at sites with low blood flow. METHODS: Thirty-six consecutive patients with intraatrial reentrant tachycardia refractory to antiarrhythmic therapy from two centers were included in the study. Entrainment pacing and electroanatomic mapping (CARTO) were used to delineate reentrant circuits and critical isthmus sites. RF ablation was performed using an irrigated-tip catheter (Navistar Thermocool). RESULTS: Fifty-two intraatrial reentrant tachycardia circuits were identified, and 48 were targeted with RF ablation. RF ablation was performed using a mean of 13 +/- 11 irrigated RF applications per tachycardia isthmus with a mean power of 36 +/- 8 W. In a historical control group of congenital heart disease patients managed with conventional catheter ablation, the number of lesions per isthmus was higher (23 +/- 11) and mean power was lower (27 +/- 14 W). Acute success was achieved in 45 intraatrial reentrant tachycardias (94% of targeted tachycardias and 87% of all tachycardias). After a mean follow-up of 17 +/- 7 months, 33 (92%) of 36 patients were free of recurrence. Five patients (14%) developed paroxysmal atrial fibrillation. CONCLUSIONS: The combination of modern techniques including electroanatomic mapping and catheter irrigation allows safe and highly effective ablation of intraatrial reentrant tachycardia in patients with surgically repaired congenital heart disease.