Electrophysiologic Effects of Growth Hormone Post-Myocardial Infarction.

Myocardial infarction remains a major health-related problem with significant acute and long-term consequences. Acute coronary occlusion results in marked electrophysiologic alterations that can induce ventricular tachyarrhythmias such as ventricular tachycardia or ventricular fibrillation, often heralding sudden cardiac death. During the infarct-healing stage, hemodynamic and structural changes can lead to left ventricular dilatation and dysfunction, whereas the accompanying fibrosis forms the substrate for re-entrant circuits that can sustain ventricular tachyarrhythmias. A substantial proportion of such patients present clinically with overt heart failure, a common disease-entity associated with high morbidity and mortality. Several lines of evidence point toward a key role of the growth hormone/insulin-like growth factor-1 axis in the pathophysiology of post-infarction structural and electrophysiologic remodeling. Based on this rationale, experimental studies in animal models have demonstrated attenuated dilatation and improved systolic function after growth hormone administration. In addition to ameliorating wall-stress and preserving the peri-infarct myocardium, antiarrhythmic actions were also evident after such treatment, but the precise underlying mechanisms remain poorly understood. The present article summarizes the acute and chronic actions of systemic and local growth hormone administration in the post-infarction setting, placing emphasis on the electrophysiologic effects. Experimental and clinical data are reviewed, and hypotheses on potential mechanisms of action are discussed. Such information may prove useful in formulating new research questions and designing new studies that are expected to increase the translational value of growth hormone therapy after acute myocardial infarction.

Should Deferred Stenting Still Be Considered in ST-Elevation Myocardial Infarction with High Thrombus Burden?

Patients with ST-elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PCI) may demonstrate distal microvascular embolization of thrombotic materials. We retrospectively examined 20 cases displaying extensive thrombus in the infarct-related artery (IRA), treated either with a two-step procedure, with interim tirofiban infusion, or immediate stent implantation. Distal embolization tended to be more common in the latter strategy, but, overall, the outcome was comparable. Thus, a two-staged procedure may be considered in selected cases of primary PCI associated with high thrombus burden.

Treatment of Mobile Right Heart Thrombi.

Right heart thrombi are detected in approximately 4% of patients with pulmonary embolism. The associated mortality is high, but the optimal strategy remains controversial. We report a case of a large mobile right heart thrombus, complicated by embolism of the right pulmonary artery, which was successfully treated with half-dose alteplase. We briefly review the literature and discuss the therapeutic options, focusing on the advantages of thrombolysis. LEARNING POINTS: Mobile right heart thrombi require rapid therapeutic choices between surgical thrombectomy and thrombolysis.Half-dose alteplase may be effective, even in the presence of an extensive thrombus burden.