Search

Increasing implantable cardioverter-defibrillator (ICD) use in response to broad indications in recent years has heightened the need to better refine selection for patients most likely to benefit. Although no single test adequately predicts sudden cardiac death risk, it seems intuitive that the best markers should be those that directly reflect electric instability and abnormalities of the underlying myocardial substrate. The advanced recording capacity of ICDs allows detailed investigation of spontaneous ventricular tachycardia (VT) episodes that would previously have been inaccessible and to potentially aid in documenting characteristics of clinically significant VTs. Different VTs occurring in the same patient can vary in stability, duration, and hemodynamic consequence. The ability to document and monitor for certain distinguishing features might provide new insights into the underlying pathophysiology and thus help to inform assessments of risk. Although ICDs discriminate between VTs primarily based on differences in rate, stored electrograms (EGMs) also have been used to help identify the arrhythmia origin and in a recent study, to help discriminate likely regions of origin for different “clinical” VTs while pace mapping in patients postinfarction.1 Article see p 33 In this issue of Circulation: Arrhythmia and Electrophysiology , Hadid et al2 analyze stored EGMs to evaluate the incidence and predictive value of pleomorphic VT and multiple VT morphologies among patients enrolled in the DATAS (Dual Chamber and Atrial Tachyarrhythmias Adverse Events Study) trial,3 in which ICDs were implanted under standard class I indications according to the 1998 American College of Cardiology/American Heart Association guidelines, as well as for MUSTT (Multicenter Unsustained Tachycardia Trial) criteria after November 2001. This study is the first to use ICD EGMs to systematically study pleomorphic VT, which was defined as a single VT episode having >1 stable ICD EGM morphology, each lasting at least 6 consecutive beats. The incidence …

Emerging metabolomic tools have created the opportunity to establish metabolic signatures of myocardial injury. We applied a mass spectrometry–based metabolite profiling platform to 36 patients undergoing alco-hol septal ablation treatment for hypertrophic obstructive cardiomyopathy, a human model of planned myo-cardial infarction (PMI). Serial blood samples were obtained before and at various intervals after PMI, with patients undergoing elective diagnostic coronary angiography and patients with spontaneous myocardial infarction (SMI) serving as negative and positive controls, respectively. We identified changes in circulating levels of metabolites participating in pyrimidine metabolism, the tricarboxylic acid cycle and its upstream con-tributors, and the pentose phosphate pathway. Alterations in levels of multiple metabolites were detected as early as 10 minutes after PMI in an initial derivation group and were validated in a second, independent group of PMI patients. A PMI-derived metabolic signature consisting of aconitic acid, hypoxanthine, trimethylamine N-oxide, and threonine differentiated patients with SMI from those undergoing diagnostic coronary angiogra-phy with high accuracy, and coronary sinus sampling distinguished cardiac-derived from peripheral metabolic changes. Our results identify a role for metabolic profiling in the early detection of myocardial injury and sug-gest that similar approaches may be used for detection or prediction of other disease states.