Andi Schaechter

Rationale and design for the Defibrillators to Reduce Risk by Magnetic Resonance Imaging Evaluation (DETERMINE) trial.

Background: Cardiac magnetic resonance imaging (CMR) can accurately determine infarct size. Prior studies using indirect methods and CMR to assess infarct size have shown that patients with larger myocardial infarctions have worse prognoses. Implantable cardioverter defibrillators (ICD) have been shown to improve survival among patients with severe left ventricular (LV) dysfunction. However, the majority of cardiac arrests occur in patients with higher ejection fractions.

Accuracy of Mode Switch Algorithms for Detection of Atrial Tachyarrhythmias

Introduction: In patients with permanent pacemakers, mode switching events often are interpreted as surrogate markers for atrial tachyarrhythmias. The aim of this study was to determine the accuracy of automatic mode switching algorithms in patients with permanent pacemakers for the diagnosis of atrial tachyarrhythmias.

Prognostic value and temporal behavior of the planar QRS-T angle in patients with nonischemic cardiomyopathy.

Background— The planar QRS-T angle can be easily obtained from standard 12-lead ECGs, but its predictive ability is not established. We sought to determine the predictive ability of the planar QRS-T angle in patients with nonischemic cardiomyopathy and to assess QRS-T angle behavior over time. Methods and Results— Baseline QRS-T angles from 455 patients in the Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial were measured. All patients had nonischemic cardiomyopathy, New York Heart Association class I to III heart failure, and nonsustained ventricular tachycardia or frequent ventricular ectopy. The primary end point (a composite of total mortality, appropriate implantable cardioverter-defibrillator shock, or resuscitated cardiac arrest) occurred in 25 of 172 patients (14.5%) with a QRS-T angle ≤90° and in 72 of 283 patients (25.4%) with a QRS-T angle >90° (hazard ratio, 1.93; 95% confidence interval, 1.23 to 3.05; P=0.002). A QRS-T angle >90° remained a significant predictor of the primary end point (P=0.039) after adjustment for treatment group, age, gender, QRS duration, left bundle-branch block, left ventricular ejection fraction, New York Heart Association class III, atrial fibrillation, and diabetes mellitus. The secondary end point (total mortality) occurred in 17 of the 172 patients (9.9%) with a QRS-T angle ≤90° and in 49 of the 283 patients (17.3%) with a QRS-T angle >90° (hazard ratio, 1.79; 95% confidence interval, 1.03 to 3.10; P=0.016). A sample of 152 patients with multiple follow-up ECGs was analyzed to assess temporal QRS-T angle behavior. Changes in the QRS-T angle correlated with changes in left ventricular ejection fraction and QRS duration over time (P<0.001). Conclusions— A planar QRS-T angle >90° is a significant predictor of a composite end point of death, appropriate implantable cardioverter-defibrillator shock, or resuscitated cardiac arrest in nonpaced, mild to moderately symptomatic patients with nonischemic cardiomyopathy with frequent or complex ventricular ectopy. QRS-T angles changed predictably with left ventricular ejection fraction and QRS duration.

Ventricular Arrhythmia Inducibility Predicts Subsequent ICD Activation in Nonischemic Cardiomyopathy Patients: A DEFINITE Substudy

Objectives: We evaluated whether electrophysiologic (EP) inducibility predicts the subsequent occurrence of spontaneous ventricular tachycardia (VT) or ventricular fibrillation (VF) in the Defibrillators in Nonischemic Cardiomyopathy Treatment Evaluation (DEFINITE) trial.

Effectiveness of shielding for patients during cardiac catheterization or electrophysiologic testing.

1. Magee AG, McCrindle BW, Mawson J, Benson LN, Williams WG, Freedom RM. Systemic venous collateral development after the bidirectional cavopulmonary anastomosis. Prevalence and predictors. J Am Coll Cardiol 1998;32:502– 508. 2. McElhinney DB, Reddy VM, Hanley FL, Moore P. Systemic venous collateral channels causing desaturation after bidirectional cavopulmonary anastomosis: evaluation and management. J Am Coll Cardiol 1997;30:817–824. 3. Gatzoulis MA, Shinebourne EA, Redington AN, Rigby ML, Ho SY, Shore DF. Increasing cyanosis early after cavopulmonary connection caused by abnormal systemic venous channels. Br Heart J 1995;73:182–186. 4. Filippini LH, Ovaert C, Nykanen DG, Freedom RM. Reopening of persistent left superior caval vein after bidirectional cavopulmonary connections. Heart 1998;79:509–512. 5. Yoshimura N, Yamaguchi M, Oshima Y, Tei T, Ogawa K. Intrahepatic venovenous shunting to an accessory hepatic vein after Fontan type operation. Ann Thorac Surg 1999;67:1494–1496. 6. Fernandez-Martorell P, Sklansky MS, Lucas VW, Kashani IA, Cocalis MW, Jamieson SW, Rothman A. Accessory hepatic vein to pulmonary venous atrium as a cause of cyanosis after the Fontan operation. Am J Cardiol 1996;77:1386– 1387.

Acute and long-term outcome of failed percutaneous transluminal coronary angioplasty treated by directional coronary atherectomy

Abstract Since its initial performance, balloon percutaneous transluminal coronary angioplasty (PTCA) has been limited by a small but finite incidence of acute coronary dissection. This can result in abrupt vessel closure, usually managed with urgent coronary artery bypass grafting. Despite improvements in equipment, technique, and operator experience, the need for urgent bypass after PTCA has remained relatively stable at 2% to 5%, due in part to the expanding indications of the procedure and its use in patients with more complicated conditions and lesions. 1 Techniques that have been used to stabilize acute coronary dissections and avoid emergency coronary bypass surgery include repeat FTCA balloon inflations, prolonged balloon inflations with perfusion balloons, 2,3 laser balloons, 4 and permanent and temporary stenting. 5,6 The recent availability of directional coronary atherectomy (DCA) has made possible an additional technique for the acute treatment of coronary dissection. 7 The purpose of this report is to assess both the acute and long-term efficacy of directional coronary atherectomy for the treatment of failed PTCA due to refractory abrupt closure.

Electrocardiographic markers of myocardial infarction size, transmural extent, and extent of nonviable myocardium - comparison to CMR

Background Myocardial infarction (MI) size is an important determinant of mortality in post-MI patients, but the current gold standard test, cardiovascular magnetic resonance imaging (CMR), is expensive and not widely available. We sought to determine whether information from a readily available standard 12-lead electrocardiogram (ECG) could be utilized to estimate infarct size, extent of transmural infarction, and extent of nonviable myocardium on CMR.