Background-Q waves on a 12-lead ECG are markers of a prior myocardial infarction (MI). However, they may regress or even disappear over time, and there is no specific ECG sign of a non-Q-wave MI. Fragmented QRS complexes (fQRSs), which include various RSRЈ patterns, without a typical bundle-branch block are markers of altered ventricular depolarization owing to a prior myocardial scar. We postulated that the presence of an fQRS might improve the ability to detect a prior MI compared with Q waves alone by ECG. Methods and Results-A cohort of 479 consecutive patients (meanϮSD age, 58.2Ϯ13.2 years; 283 males) who were referred for nuclear stress tests was studied. The fQRS included various morphologies of the QRS (Ͻ120 ms), which included an additional R wave (RЈ) or notching in the nadir of the S wave, or Ͼ1 RЈ (fragmentation) in 2 contiguous leads, corresponding to a major coronary artery territory. The Q wave was present in 71 (14.8%) patients, an fQRS was present in 191 (34.9%) patients, and an fQRS and/or a Q wave was present in 203 (42.3%) patients. Sensitivity, specificity, and the negative predictive value for myocardial scar as detected by single photon emission computed tomography analysis were 36.3%, 99.2%, and 70.8%, respectively, for the Q wave alone; 85.6%, 89%, and 92.7%, respectively, for the fQRS; and 91.4%, 89%, and 94.2%, respectively, for the Q wave and/or fQRS. Conclusions-The fQRS on a 12-lead ECG is a marker of a prior MI, defined by regional perfusion abnormalities, which has a substantially higher sensitivity and negative predictive value compared with the Q wave.

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Background-Fragmented QRS (duration Ͻ120 ms) on a 12-lead ECG represents myocardial scar in patients with coronary artery disease. However, the significance of fragmented QRS has not been defined in the presence of a wide QRS (wQRS; duration Ն120 ms). We postulate that fragmented wQRS (f-wQRS) due to bundle branch block, premature ventricular complexes, or paced rhythms (f-pQRS) signify myocardial scar and higher mortality. Methods and Results-Patients who underwent cardiac evaluation with nuclear stress imaging or cardiac catheterization and had wQRS (bundle branch block, premature ventricular complex, or pQRS) were studied. f-wQRS was defined by the presence of Ͼ2 notches on the R wave or the S wave and had to be present in Ն2 contiguous inferior (II, III, aVF), lateral (I, aVL, V 6 ) or anterior (V 1 to V 5 ) leads. ECG analyses of 879 patients (age, 66.7Ϯ11.4 years; male, 97%; mean follow-up, 29Ϯ18 months) with bundle branch block (nϭ310), premature ventricular complex (nϭ301), and pQRS (nϭ268) revealed f-wQRS in 415 (47.2%) patients. Myocardial scar was present in 440 (50%) patients. The sensitivity, specificity, positive predictive value, and negative predictive value of f-wQRS for myocardial scar were 86.8%, 92.5%, 92.0%, and 87.5%, respectively. The sensitivity and specificity for diagnosing myocardial scar were 88.6% and 94.4%, 81.4% and 88.4%, and 89.8% and 95.7% for f-bundle branch block, f-premature ventricular complex, and f-pQRS, respectively. f-wQRS was associated with mortality after adjusting for age, ejection fraction, and diabetes (Pϭ0.017). Conclusions-f-wQRS on a standard 12-lead ECG is a moderately sensitive and highly specific sign for myocardial scar in patients with known or suspected coronary artery disease. f-wQRS is also an independent predictor of mortality. (Circ Arrhythmia Electrophysiol. 2008;1:258-268.)

Background-Spinal cord stimulation (SCS) reduces the incidence of ventricular tachyarrhythmias in experimental models. This study investigated the effects of long-term SCS on ventricular function in a postinfarction canine heart failure model. Methods and Results-In stage 1, dogs underwent implantable cardioverter-defibrillator implantation and embolization of the left anterior descending artery followed by right ventricular pacing (240 ppm) for 3 weeks to produce heart failure. In stage 2, 28 surviving animals were assigned to the SCS (delivered at the T4/T5 spinal region for 2 hours 3 times a day), medicine (MED; carvedilol therapy at 12.5 mg PO BID), or control (CTRL; no therapy) group for the initial phase 1 study. In a subsequent phase 2 study, 32 stage 1 survivors were equally randomized to the SCS, MEDS (carvedilol plus ramipril 2.5 mg PO QD), SCS plus MEDS (concurrent therapy), or CTRL group. Animals were monitored for 5 weeks (phase 1) or 10 weeks (phase 2). In stage 3, all phase 1 animals underwent circumflex artery balloon occlusion for 1 hour. In the SCS group, left ventricular ejection fraction was 65Ϯ5% at baseline, 17Ϯ3% at the end of stage 1, and 47Ϯ7% at the end of stage 2. In the MED group, left ventricular ejection fraction was 61Ϯ4% at baseline, 18Ϯ3% at the end of stage 1, and 34Ϯ4% at the end of stage 2. In the CTRL group, left ventricular ejection fraction was 64Ϯ5% at baseline, 19Ϯ5% at the end of stage 1, and 28Ϯ3% at the end of stage 2. Left ventricular ejection fraction was significantly improved in the SCS compared with the MED and CTRL groups (PϽ0.001 for both). The mean number of spontaneous nonsustained ventricular tachyarrhythmias during stage 2 and the occurrence of ischemic ventricular tachyarrhythmias during stage 3 also were significantly decreased in the SCS (27Ϯ17 and 27%, respectively; PϽ0.03) and MED (58Ϯ42 and 33%; PϽ0.05) versus CTRL (88Ϯ52 and 76%) group. After 10 weeks in the phase 2 studies, the greatest recovery in ejection fraction was noted in the SCS (52Ϯ5%) and SCSϩMEDS (46Ϯ4%) groups compared with the MEDS (38Ϯ2%) and CTRL (31Ϯ4%) groups. Conclusion-SCS

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