We describe a new ECG algorithm having a high sensitivity and specificity to identify the optimal ablation site for idiopathic ventricular outflow tachycardia or premature ventricular contractions.

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Subtle variations in QRS morphology occurs during idiopathic outflow tract ventricular tachycardia (OTVT), but no studies have clarified the prevalence and characteristics of the OTVT with altered QRS morphology following radiofrequency catheter ablation (RFA), which then require an additional RF application at a different portion of the outflow tract to abolish OTVT. Of 202 patients with a monomorphic VT or premature ventricular contraction (PVC) originating from the outflow tract, 6 (3%) showed changes in QRS morphology in the OTVT following RFA, requiring an additional RF application to the outflow tract at a different portion. In all six patients, RFA was applied for the first or second OTVT to a right or left ventricular endocardial site, with the other site being the left sinus of Valsalva. In each patient, OTVT before or after the changes in QRS morphology had characteristic ECG findings originating from a particular portion of the outflow tract. Changes in QRS morphology consistently included an increase or decrease in R wave amplitude in all inferior leads. Detailed continuous observation of QRS morphology in OTVT, especially R wave amplitude in inferior leads, is important for identifying changes of QRS morphology during catheter ablation. Mapping and ablation at a different portion of the outflow tract is then needed for cure.

Background-The delayed release of serum cardiac markers such as creatine kinase isoenzyme MB and equivocal early electrocardiographic changes have hampered a diagnosis of acute myocardial infarction (AMI) in the early phase after its onset. Therefore, a reliable serum biochemical marker for the diagnosis of AMI in the very early phase is desirable. Methods and Results-Serum samples were collected from the patients with AMI, unstable angina pectoris, stable angina pectoris, and other diseases. Levels of serum deoxyribonuclease I (DNase I) activity in the patients were determined. An abrupt elevation of serum DNase I activity was observed within approximately 3 hours of the onset of symptoms in patients with AMI, with significantly higher activity levels (21.7Ϯ5.10 U/L) in this group compared with the other groups with unstable angina pectoris (10.4Ϯ4.41 U/L), angina pectoris (10.8Ϯ3.70 U/L), and other diseases (9.22Ϯ4.16 U/L). Levels of the DNase I activity in serum then exhibited a marked time-dependent decline within 12 hours and had returned to basal levels within 24 hours. Conclusions-We suggest that serum DNase I activity could be used as a new diagnostic marker for the early detection of AMI. Key Words: myocardial infarction Ⅲ enzymes Ⅲ diagnosis I n patients with acute myocardial infarction (AMI), the infarct size is an important determinant of both mortality and morbidity. 1 When revascularization and thrombolytic therapies are initiated rapidly, there is a greater potential for reduction in the infarct size. The release of cardiac proteins from injured cardiac tissue into plasma has been used as a diagnostic marker for the exclusion or confirmation of AMI. 2 However, it is often difficult to make a diagnosis of AMI in the very early phase, ie, within 3 hours of onset. This is partly due to a delay in the appearance in the serum of the biochemical markers specific for myocardial damage. 2,3 Deoxyribonuclease I (DNase I, EC 3.1.21.1), one of the well-known enzymes, was the first enzyme to be recognized as specific for DNA. 4 One of its proposed roles is DNA breakdown during apoptosis. 5 DNase I has been detected in human myocardium, and it has been reported that the activity level increases in heart failure due to idiopathic dilated cardiomyopathy. 6 However, the association between serum DNase I activity level and coronary heart disease (CHD) has not yet been clarified. In the present study, we assessed the serum DNase I activity in patients with AMI and related CHD and found that there is a specific elevation of serum DNase I activity in the very early stages of AMI. Methods Patients and Sample CollectionWe assessed 53 consecutive Japanese patients with AMI admitted to our hospitals between September 2002 and May 2003. The clinical diagnosis of AMI and unstable angina pectoris (UAP) was made according to the European Society of Cardiology/American College of Cardiology Committee criteria. 7 The mean lapse time between the onset of symptoms and hospital admission was 10.7Ϯ13.8 hours. Emergent coronary ang...