Sinoatrial arrest associated with Takotsubo cardiomyopathy

Takotsubo Syndrome and Sudden Cardiac Death

Takotsubo syndrome (TTS), triggered by intense emotional or physical stress, occurring most commonly in post-menopausal women, presents as an ST-elevation myocardial infarction (MI). Cardiovascular complications occur in almost half the patients with TTS, and the inpatient mortality is comparable to MI (4-5%) owing to cardiogenic shock, myocardial rupture, or life-threatening arrhythmias. Thus, its prognosis is not as benign as previously thought, as it may cause mechanical complications (cardiac rupture) and potentially lethal arrhythmias and sudden cardiac death (SCD). Similar to MI, some patients may perish before reaching the hospital due to out-of-hospital cardiac arrest; this may lead to underestimation of the actual SCD risk. Furthermore, after discharge, some patients may develop late SCD and/or TTS recurrence that may result in SCD. There are risk factors for SCD in TTS patients, such as severe/persistent QT-interval prolongation inciting torsade-de-pointes, other ECG abnormalities (diffuse giant negative T-waves, widened QRS-complex), bradyarrhythmias, comorbidities, concurrent obstructive coronary artery disease or vasospasm, male gender, older age, severe left ventricular dysfunction, and use of sympathomimetic drugs. All these issues are herein reviewed, case reports/series and data from large cohort studies and meta-analyses are analyzed, risk factors are tabulated, and proarrhythmic effects and management strategies are discussed and pictorially illustrated.

Takotsubo Cardiomyopathy Presenting with Sinoatrial Disease: A Rare Presentation

Takotsubo cardiomyopathy (TCM), or apical ballooning syndrome, is a distinct nonischemic cardiomyopathy mimicking acute coronary syndrome. A 76-year-old female presented with ST elevation in the inferior lead and a troponin level of 0.81 ng/dL. An immediate coronary angiography showed non-obstructive coronary artery disease. A subsequent ventriculogram and echocardiogram showed anteroapical and distal inferior wall hypokinesis suggestive of TCM. Despite therapy with beta blocker, she was observed to have two significant sinus pauses, one eight-second, and a second 29-second pause. An urgent transvenous pacemaker was put in place and later followed by a permanent pacemaker. The patient was discharged on carvedilol and losartan. Although other arrhythmias such as complete heart block, torsades, and ventricular arrhythmias have been commonly reported, the association of TCM with recurrent sinus arrest has rarely been reported in the literature. The occurrence observed in this case implies that patients with TCM should be monitored closely for arrhythmias, and, if such a condition is identified, planning for permanent pacemaker implantation should be started early enough to avoid recurrent life-threatening episodes.

[Patient care in the acute phase of stress induced cardiomyopathy (Tako-Tsubo cardiomyopathy)--and thereafter?]

The prognosis of patients presenting with Tako-Tsubo cardiomyopathy (TTC) is generally considered to be favorable. However, in the acute phase of the disorder complications are not infrequent and, therefore, continuous monitoring and consistent therapy in an intensive care unit is essential. Typical complications in patients with TTC are cardiogenic shock, obstruction of the left ventricular outflow tract (LVOT), occasionally accompanied by acute mitral regurgitation, arrhythmias, predominantly torsade de pointes tachycardias due to QT prolongation, left ventricular (LV) thrombus formation with or without consecutive thromboembolic events, and LV rupture. After confirmation of TTC by coronary angiography, repeat echocardiography should be performed. A standardized therapy for patients with TTC has so far not been established. Recommendations for the acute phase include the administration of anxiolytic agents for patients who present with preceding emotional stress, consistent therapy of physical stressors (such as pain or asthma) and avoidance of catecholamine therapy. Shock due to LVOT obstruction is treated by administration of volume and β-blockers. With respect to the occurrence of torsade de pointes tachycardias, drugs which might cause QT prolongation should not be given. The notable incidence of LV thrombus formation justifies therapeutic anticoagulation. Systematic studies and treatment recommendations for the prophylaxis of recurrent TTC do not exist. The recently reported association between TTC and malignant disorders should prompt tumor screening and subsequent preventive medical checkups in patients affected by TTC.

Targeting of the Akt/PKB kinase to the actin skeleton

Serine/threonine kinase Akt/PKB intracellular distribution undergoes rapid changes in response to agonists such as Platelet-derived growth factor (PDGF) or Insulin-like growth factor (IGF). The concept has recently emerged that Akt subcellular movements are facilitated by interaction with nonsubstrate ligands. Here we show that Akt is bound to the actin skeleton in in situ cytoskeletal matrix preparations from PDGF-treated Saos2 cells, suggesting an interaction between the two proteins. Indeed, by immunoprecipitation and subcellular fractioning, we demonstrate that endogenous Akt and actin physically interact. Using recombinant proteins in in vitro binding and overlay assays, we further demonstrate that Akt interacts with actin directly. Expression of Akt mutants strongly indicates that the N-terminal PH domain of Akt mediates this interaction. More important, we show that the partition between actin bound and unbound Akt is not constant, but is modulated by growth factor stimulation. In fact, PDGF treatment of serum-starved cells triggers an increase in the amount of Akt associated with the actin skeleton, concomitant with an increase in Akt phosphorylation. Conversely, expression of an Akt mutant in which both Ser473 and Thr308 have been mutated to alanine completely abrogates PDGF-induced binding. The small GTPases Rac1 and Cdc42 seem to facilitate actin binding, possibly increasing Akt phosphorylation.