Qualitative interpretation of tomographic and planar scintigrams, a five point rating scale and receiver operating characteristic analysis were utilized to compare single photon emission computed tomography and conventional planar imaging of myocardial thallium-201 uptake in the accuracy of the diagnosis of coronary artery disease and individual vessel involvement. One hundred twelve patients undergoing cardiac catheterization and 23 normal volunteers performed symptom-limited treadmill exercise, followed by stress and redistribution imaging by both tomographic and planar techniques, with the order determined randomly. Paired receiver operating characteristic curves revealed that single photon emission computed tomography was more accurate than planar imaging over the entire range of decision thresholds for the overall detection and exclusion of coronary artery disease and involvement of the left anterior descending and left circumflex coronary arteries. Tomography offered relatively greater advantages in male patients and in patients with milder forms of coronary artery disease, who had no prior myocardial infarction, only single vessel involvement or no lesion greater than or equal to 50 to 69%. Tomography did not appear to provide improved diagnosis in women or in detection of disease in the right coronary artery. Although overall detection of coronary artery disease was not improved in patients with prior myocardial infarction, tomography provided improved identification of normal and abnormal vascular regions, particularly of the left anterior descending and circumflex artery regions. These results indicate that single photon emission computed tomography provides improved diagnostic performance compared with planar imaging in many clinical subgroups, and suggest that it represents the diagnostic imaging procedure of choice in exercise thallium-201 perfusion studies.

Introduction Outcome of cardiac resynchronization therapy is severely worsened by myocardial scar at the left ventricular (LV) pacing site. We aimed to describe the diagnostic performance of electrocardiographic (ECG) criteria based on the Selvester QRS scoring system, first in localizing myocardial scar and second in screening for any non-septal scar in patients with strictly defined LBBB. Methods and Results In 39 cardiomyopathy patients with LBBB, 17 with scar, 22 without scar, late gadolinium-enhancement cardiac magnetic resonance images (CMR-LGE) and 12-lead ECGs were analyzed for scar presence in 5 LV wall segments. The ECG criteria with the best diagnostic performance in detecting scar in each segment and in the four non-septal segments together were identified. Criteria for detecting non-septal scar had 75% (95% CI: 51%–90%) sensitivity, 95% (78%–99%) specificity, 92% (67%–99%) positive predictive value and 84% (65%–94%) negative predictive value. For each individual wall segment, 40%–60% sensitivities and 77%–100% specificities were found. Conclusions The 12-lead ECG can convey information about scar presence and location in this population of cardiomyopathy patients with LBBB. ECG screening criteria for scar in potential CRT LV pacing sites were identified. Further exploration is required to determine the clinical utility of the 12-lead ECG in combination with other imaging modalities to screen for scar in potential LV pacing sites in CRT candidates.

Introduction Inappropriate implantable cardioverter‐defibrillator (ICD) shocks, commonly caused by atrial fibrillation (AF), are associated with an increased mortality. Because impaired left atrial (LA) function predicts development of AF, we hypothesized that impaired LA function predicts inappropriate shocks beyond a history of AF. Methods and results We prospectively analyzed the association between LA function and incident inappropriate shocks in primary prevention ICD candidates. In the Prospective Observational Study of ICD (PROSE‐ICD), we assessed LA function using tissue‐tracking cardiac magnetic resonance (CMR) prior to ICD implantation. A total of 162 patients (113 males, age 56 ± 15 years) were included. During the mean follow‐up of 4.0 ± 2.9 years, 26 patients (16%) experienced inappropriate shocks due to AF (n = 19; 73%), supraventricular tachycardia (n = 5; 19%), and abnormal sensing (n = 2; 8%). In univariable analyses, inappropriate shocks were associated with AF history prior to ICD implantation, age below 70 years, QRS duration less than 120 milliseconds, larger LA minimum volume, lower LA stroke volume, lower LA emptying fraction, impaired LA maximum and preatrial contraction strains (Smax and SpreA), and impaired LA strain rate during left ventricular systole and atrial contraction (SRs and SRa). In multivariable analysis, impaired Smax (hazard ratio [HR]: 0.96, P = 0.044), SpreA (HR: 0.94, P = 0.030), and SRa (HR: 0.25, P < 0.001) were independently associated with inappropriate shocks. The receiver‐operating characteristics curve showed that SRa improved the predictive value beyond the patient demographics including AF history (P = 0.033). Conclusion Impaired LA function assessed by tissue‐tracking CMR is an independent predictor of inappropriate shocks in primary prevention ICD candidates beyond AF history.

Background Left bundle branch block (LBBB) is a marker of increased delay between septal and left ventricular (LV) lateral wall electrical activation, and is a predictor of which patients will benefit from cardiac resynchronization therapy (CRT). Recent analysis has suggested that one third of patients meeting conventional ECG criteria for LBBB are misdiagnosed and new strict LBBB criteria have been proposed. We tested the hypothesis that strict LBBB patients have greater LV mechanical dyssynchrony than patients meeting non-strict LBBB criteria while there is no difference between patients with non-strict LBBB and LV conduction delay with QRS duration 110–119 ms. Methods Sixty-four patients referred for primary prevention implantable cardioverter-defibrillators (ICD) underwent 12-lead ECG and cardiac magnetic resonance (CMR) myocardial tagging. The patients were classified as strict LBBB, non-strict LBBB or non-LBBB (nonspecific LV conduction delay with QRS duration 110–119 ms). The time delay between septal and lateral LV wall peak circumferential strain (septal-to-lateral wall delay) was measured by CMR. Results Patients with strict LBBB (n=31) had a greater septal-to-lateral wall delay, compared to patients with non-strict LBBB (n=19) (210±137 ms vs. 122±102 ms, p=0.045). There was no significant difference between non-strict LBBB and non-LBBB (n=14) septal-to-lateral wall delay (122±102 ms vs. 100±86 ms, p=0.51). Conclusions Strict-LBBB criteria identify patients with greater mechanical dyssynchrony compared to patients only meeting non-strict LBBB criteria, while there was no significant difference between non-strict LBBB and non-LBBB patients. The greater observed LV dyssynchrony may explain why strict-LBBB patients have better response to CRT.