Prognostic impact of atrial fibrillation in patients with acute myocardial infarction

Background: Atrial fibrillation (AF) is the most common supraventricular tachyarrhythmia in patients with acute myocardial infarction (AMI). However, little is known about the impact of AF on in-hospital and long-term mortalities in patients with AMI in the era of primary percutaneous coronary intervention (PCI). Methods: Six hundred ninety-four consecutive patients with AMI admitted within 48 h after symptom onset were analyzed. All patients successfully underwent primary PCI at the acute phase of AMI. Patients were divided into 2 groups according to the presence of AF at admission or during index hospitalization. We retrospectively evaluated the in-hospital and long-term all-cause mortalities between patients with and those without AF. Results: AF was detected in 38 patients (5.5%) at admission and in 51 patients (7.3%) during hospitalization. Patients with AF were older and had a higher heart rate, lower ejection fraction, higher prevalence of hypertension, worse renal function, higher peak level of creatine phosphokinase, and lower rate of final TIMI flow grade 3 than those without AF. Although patients with AF had a more complicated clinical course and higher in-hospital mortality (11.2% vs. 4.0%, P=0.009), there was no significant association between presenting AF and in-hospital death after adjustment for baseline confounders (odds ratio, 2.63; 95% confidence interval [CI], 0.91–5.47; P=0.076). During the follow-up period of 3.0±1.7 years, patients with AF had a higher all-cause mortality than those without AF (30.3% vs. 22.1%, P=0.004 by log-rank test). However, after adjustment for clinical characteristics, presenting AF was not an independent predictor of all-cause mortality (hazard ratio, 1.15; 95% CI, 0.67–1.88; P=0.588). Conclusions: AF is a common complication of AMI and associated with a more complicated clinical course. However, AF is not an independent predictor of both in-hospital and long-term mortalities in the PCI era

A case of inappropriate implantable cardioverter defibrillator shock due to epileptic seizures: A possible limitation of the Wavelet discrimination algorithm

In the present report, we describe the case of a 63-year-old man who received an inappropriate implantable cardioverter defibrillator (ICD) shock due to an epileptic seizure. He experienced an acute myocardial infarction 12 months previously, and his left ventricular (LV) ejection fraction was markedly reduced (21.1%) due to the presence of advanced LV remodeling and an LV aneurysm. An implantable cardioverter-defibrillator (ICD, Medtronic Protecta XT VR) was implanted for the primary prevention of sudden cardiac death. After the implantation, ICD shock data were transmitted via a remote monitoring system. Although many episodes of tachycardia due to atrial fibrillation (AF) were detected, inappropriate discharge was avoided by the use of the Wavelet™ morphology discrimination algorithm (Medtronic Inc., MN, USA). However, an ICD shock was inappropriately delivered for AF tachycardia accompanied by frequent noise detected in the intracardiac electrocardiogram. A detailed analysis showed that the observed noise was derived from the myopotential induced by an epileptic seizure, which overlapped with the QRS wave. This resulted in inappropriate ICD shock delivery that could not be avoided with the use of Wavelet algorithm. To eliminate the involvement of the myopotential derived from an epileptic seizure, the nominal direction of the intracardiac electrocardiogram was changed. This adjustment prevented inappropriate ICD shock delivery during subsequent epileptic seizures. Here, we describe for the first time a case of inappropriate ICD shock delivery induced by an epileptic seizure, suggesting a possible limitation of the Wavelet discrimination algorithm