Atrial Fibrillation in Anaphylaxis.

BACKGROUND: The relationship between anaphylaxis and cardiovascular events has been reported in the past. While skin and respiratory symptoms are usually the most common and the first to appear, cardiovascular complications play a key role and represent the leading cause of death in anaphylaxis. METHODS: We report 3 episodes of atrial fibrillation triggered by anaphylaxis. Allergy and cardiology studies were performed. In both patients, the etiological agent was identified: Anisakis simplex hypersensitivity and food allergy. RESULTS: The heart is the source and target of chemical mediators released during an allergic reaction. In the heart, there are plenty of mast cells, and they are predominantly located around the coronary adventitia and in close contact with small vessels in the muscle wall. The release of mediators can influence ventricular function, heart rate, and coronary artery tone. Anaphylaxis can trigger any kind of arrhythmia. In these cases, the very interesting point of discussion was: which should be first, treating anaphylaxis or cardiac events? The other controversial point was the use of epinephrine, the first line of treatment for anaphylaxis. Recommendations about epinephrine in cardiac patients during an anaphylactic event are still a major dilemma. CONCLUSIONS: We emphasize the importance of the priority of establishing protocols between cardiologist and allergist in treatment of cardiac complications during anaphylaxis, and we warn about the correct diagnosis of arrhythmias in anaphylaxis in order to treat them as soon as possible, to prevent other consequences and complications.

Specificity of electrocardiographic criteria for the differential diagnosis of wide QRS complex tachycardia in patients with intraventricular conduction defect.

BACKGROUND: In patients with organic intraventricular conduction defects (IVCDs), (1) QRS morphology during sinus rhythm frequently meets ventricular tachycardia (VT) morphological criteria and (2) there are further rate-related changes in QRS morphology. OBJECTIVE: To search for the best morphological criteria in this context. METHODS: We prospectively studied 69 patients, in sinus rhythm, with QRS duration ≥120 ms. Continuous rapid atrial pacing (RAP) trains were introduced at increasing rates in order to mimic supraventricular tachycardia. We analyzed the specificity of VT criteria during RAP. Finally, we used the criteria with a specificity of ≥0.9 in a "test sample" of 53 patients with preexisting IVCD and wide complex tachycardia to confirm their validity. RESULTS: Only 10 of the 20 analyzed criteria had a specificity of ≥0.9 during RAP at the highest rate. The specificity of these 10 criteria was confirmed in the test sample. The best accuracy to diagnose VT was obtained: for an isolated criterion: "R-wave peak time (RWPT) ≥50 ms at lead II" (specificity = 0.97; sensitivity = 0.67); for an algorithm: the combination of 2 criteria "RWPT ≥50 ms at lead II" and "absence of RS patterns in precordial leads" (specificity = 0.97; sensitivity = 0.88). CONCLUSIONS: In patients with IVCD, (1) specificity of most VT criteria is low during RAP, suggesting a limited applicability of many of these criteria in case they develop supraventricular tachycardia, and (2) the superior accuracy to diagnose VT was observed with "RWPT ≥50 ms at lead II" and for an algorithm with the combination of "RWPT ≥50 ms at lead II" and "absence of RS patterns in precordial leads."