Takotsubo Syndrome After Pacemaker Implantation: A Case Report and Literature Review.

A 78-year-old male patient with complete atrioventricular block underwent an uncomplicated pacemaker implantation. After 24 h, he presented acute chest pain, dyspnea, ST-segment-elevation in the anterior leads, left ventricular apical ballooning, and an ejection fraction of 35%. His coronary angiogram was normal. Within 2 days, his symptoms and electrocardiogram (ECG) abnormalities disappeared, while wall motion abnormalities recovered after 6 weeks. A diagnosis of takotsubo syndrome (TTS) was made. Pacemaker implantation has been described as a potential trigger for TTS. The clinical picture exhibits some peculiarities, including a higher percentage of men and asymptomatic patients and challenging ST-segment interpretation of paced ECGs. It is unclear whether pathophysiologic mechanisms are different compared to other forms of TTS and whether the acute initiation of ventricular pacing plays a role.

Dynamic changes in T-wave and QTc interval during tilt table testing: Innocent until proven otherwise.

A16-year-old female underwent tilt table testing, which resulted positive for reflex vasodepressive syncope. 12­lead ECG during syncope showed T-wave inversion in infero-lateral leads, along with QTc interval increase >100 msec compared to baseline. These abnormalities rapidly disappeared in supine position with resumption of consciousness. Complete cardiac evaluation excluded heart disease. T-wave changes and moderate QTc prolongation are relatively common in young (mainly female) patients undergoing tilt table testing and they appear benign in nature. However, in a minority of cases, on the basis of the clinical context and after an accurate ECG analysis, further examinations may be warranted.

Brugada ECG pattern in hypertrophic cardiomyopathy: Brugada phenocopy or overlapping syndrome?

The term phenocopy indicates a condition that imitates one produced by a gene and is also used for acquired Brugada-like ECG manifestations. Cases of Brugada phenocopies are increasingly reported in literature and an international registry is ongoing. We describe two patients with Hypertrophic Cardiomyopathy (HCM) and Brugada ECG pattern. Both patients carried the same pathogenic splicing mutation in MYBPC3 gene (responsible for HCM) while no genetic mutation associated with Brugada Syndrome was identified. To the best of our knowledge, Brugada ECG pattern has been rarely reported in patients with HCM.

Cardiac magnetic resonance imaging: Which information is useful for the arrhythmologist?

Cardiac magnetic resonance (CMR) is a non-invasive, non-ionizing, diagnostic technique that uses magnetic fields, radio waves and field gradients to generate images with high spatial and temporal resolution. After administration of contrast media (e.g., gadolinium chelate), it is also possible to acquire late images, which make possible the identification and quantification of myocardial areas with scar/fibrosis (late gadolinium enhancement, LGE). CMR is currently a useful instrument in clinical cardiovascular practice for the assessment of several pathological conditions, including ischemic and non-ischemic cardiomyopathies and congenital heart disease. In recent years, its field of application has also extended to arrhythmology, both in diagnostic and prognostic evaluation of arrhythmic risk and in therapeutic decision-making. In this review, we discuss the possible useful applications of CMR for the arrhythmologist. It is possible to identify three main fields of application of CMR in this context: (1) arrhythmic and sudden cardiac death risk stratification in different heart diseases; (2) decision-making in cardiac resynchronization therapy device implantation, presence and extent of myocardial fibrosis for left ventricular lead placement and cardiac venous anatomy; and (3) substrate identification for guiding ablation of complex arrhythmias (atrial fibrillation and ventricular tachycardias).

Ticagrelor therapy and atrioventricular block: Do we need to worry?

Ticagrelor is a potent, direct P2Y12 antagonist with rapid onset of action and intense platelet inhibition, indicated in patients with acute coronary syndromes (ACS). This drug is usually well tolerated, but some patients experience serious adverse effects: Major bleeding; gastrointestinal disturbances; dyspnoea; ventricular pauses > 3 s. Given the unexpected high incidence of bradyarrhythmias, a PLATO substudy monitored this side effect, showing that ticagrelor was associated with an increase in the rate of sinus bradycardia and sinus arrest compared to clopidogrel. This side effect was usually transient, asymptomatic and not associated with higher incidence of severe atrioventricular (AV) block or pacemaker needs. A panel of experts from Food and Drug Administration did not consider bradyarrhythmias a serious problem in clinical practice and, accordingly, current labeling of the drug does not give any precaution or contraindication regarding this issue. However, recently some articles have described ACS patients with high-degree, life-threatening, AV block requiring drug discontinuation and, in some cases, pacemaker implantation. In this paper, we describe and discuss five published case reports of severe AV block following ticagrelor therapy and two other cases managed in our Hospital. The analysis of literature suggests that, although rarely, ticagrelor can be associated with life-threatening AV block. Caution and careful monitoring are required especially in patients with already compromised conduction system and/or treated with AV blocking agents. Future studies, with long-term rhythm monitoring, would help to define the outcome of patients at higher risk of developing this complication.

Antitachycardia pacing programming in implantable cardioverter defibrillator: A systematic review.

Implantable cardioverter defibrillator (ICD) programming involves several parameters. In recent years antitachycardia pacing (ATP) has gained an increasing importance in the treatment of ventricular arrhythmias, whether slow or fast. It reduces the number of unnecessary and inappropriate shocks and improves both patient's quality of life and device longevity. There is no clear indication regarding the type of ATP to be used, except for the treatment of fast ventricular tachycardias (188 bpm-250 bpm) where it has been shown a greater efficacy and safety of burst compared to ramp; 8 impulses in each sequence of ATP appears to be the best programming option in this setting. Beyond ATP use, excellent clinical results were obtained with programming standardization following these principles: extended detection time in ventricular fibrillation (VF) zone; supraventricular discrimination criteria up to 200 bpm; first shock in VF zone at the maximum energy in order to reduce the risk of multiple shocks. The MADIT-RIT trial and some observational registries have also recently demonstrated that programming with a widespread use of ATP, higher cut-off rates or delayed intervention reduces the number of inappropriate and unnecessary therapies and improves the survival of patients during mid-term follow-up.

Externalized conductors and insulation failure in Biotronik defibrillator leads: History repeating or a false alarm?

Conductor externalization and insulation failure are frequent complications with the recalled St. Jude Medical Riata implantable cardioverter-defibrillator (ICD) leads. Conductor externalization is a "unique" failure mechanism: Cables externalize through the insulation ("inside-out" abrasion) and appear outside the lead body. Recently, single reports described a similar failure also for Biotronik leads. Moreover, some studies reported a high rate of electrical dysfunction (not only insulation failure) with Biotronik Linox leads and a reduced survival rate in comparison with the competitors. In this paper we describe the case of a patient with a Biotronik Kentrox ICD lead presenting with signs of insulation failure and conductor externalization at fluoroscopy. Due to the high risk of extraction we decided to implant a new lead, abandoning the damaged one; lead reimplant was uneventful. Subsequently, we review currently available literature about Biotronik Kentrox and Linox ICD lead failure and in particular externalized conductors. Some single-center studies and a non-prospective registry reported a survival rate between 88% and 91% at 5 years for Linox leads, significantly worse than that of other manufacturers. However, the preliminary results of two ongoing multicenter, prospective registries (GALAXY and CELESTIAL) showed 96% survival rate at 5 years after implant, well within industry standards. Ongoing data collection is needed to confirm longer-term performance of this family of ICD leads.

Riata silicone defibrillation lead with normal electrical measures at routine ambulatory check: The role of high-voltage shock testing.

AIM: To describe our experience with shock testing for the evaluation of patients with Riata™ leads. METHODS: Among 51 patients with normal baseline electrical parameters, 20 died during follow-up. Of the remaining 31 patients, 15 underwent the test: In 10 cases a defibrillation testing with ventricular fibrillation (VF) induction and in 5 cases a R-wave-synchronized shock (> 20 J, without inducing VF). The test was performed under sedation with Midazolam. RESULTS: Twelve patients (80%) had a normal behavior during shock testing: In 8 cases induced VF was correctly detected and treated; in 4 cases of R-wave-synchronized shock electrical parameters remained stable and normal. Three patients (20%) failed the test. One patient with externalized conductors showed a sudden drop of high-voltage impedance (< 10 Ohm) after a 25 J R-wave-synchronized shock. Two other patients with externalized conductors, undergoing defibrillation testing, showed a short-circuit during shock delivery and the implantable cardioverter defibrillator was unable to interrupt VF. CONCLUSION: In Riata™ leads the delivery of a low current during routine measurement of high-voltage impedance may not reveal a small short circuit, that can only be evident by attempting to deliver a true shock, either for spontaneous arrhythmias or in the context of a shock testing.

Radial versus femoral randomized investigation in ST-segment elevation acute coronary syndrome: the RIFLE-STEACS (Radial Versus Femoral Randomized Investigation in ST-Elevation Acute Coronary Syndrome) study.

OBJECTIVES: The purpose of this study was to assess whether transradial access for ST-segment elevation acute coronary syndrome undergoing early invasive treatment is associated with better outcome compared with conventional transfemoral access. BACKGROUND: In patients with acute coronary syndrome, bleeding is a significant predictor of worse outcome. Access site complications represent a significant source of bleeding for those patients undergoing revascularization, especially when femoral access is used. METHODS: The RIFLE-STEACS (Radial Versus Femoral Randomized Investigation in ST-Elevation Acute Coronary Syndrome) was a multicenter, randomized, parallel-group study. Between January 2009 and July 2011, 1,001 acute ST-segment elevation acute coronary syndrome patients undergoing primary/rescue percutaneous coronary intervention were randomized to the radial (500) or femoral (501) approach at 4 high-volume centers. The primary endpoint was the 30-day rate of net adverse clinical events (NACEs), defined as a composite of cardiac death, stroke, myocardial infarction, target lesion revascularization, and bleeding). Individual components of NACEs and length of hospital stay were secondary endpoints. RESULTS: The primary endpoint of 30-day NACEs occurred in 68 patients (13.6%) in the radial arm and 105 patients (21.0%) in the femoral arm (p = 0.003). In particular, compared with femoral, radial access was associated with significantly lower rates of cardiac mortality (5.2% vs. 9.2%, p = 0.020), bleeding (7.8% vs. 12.2%, p = 0.026), and shorter hospital stay (5 days first to third quartile range, 4 to 7 days] vs. 6 [range, 5 to 8 days]; p = 0.03). CONCLUSIONS: Radial access in patients with ST-segment elevation acute coronary syndrome is associated with significant clinical benefits, in terms of both lower morbidity and cardiac mortality. Thus, it should become the recommended approach in these patients, provided adequate operator and center expertise is present. (Radial Versus Femoral Investigation in ST Elevation Acute Coronary Syndrome [RIFLE-STEACS]; NCT01420614).