Prognostic significance of ischemic electrocardiographic changes during stress testing in patients with normal nuclear myocardial perfusion imaging

Objectives: The main objective of this study was to evaluate cardiovascular outcome in patients with normal nuclear myocardial perfusion imaging but ischemic ECG changes during pharmacological or exercise stress test. Methods: In this retrospective study, we included a cohort of patients who underwent either pharmacological or exercise stress MPS and have a normal scan with ischemic EKG changes at Aga Khan University Hospital, from January 2013 to December 2014. All cardiac events including angina, myocardial infarction, heart failure, coronary revascularization and cardiac death as well as non-cardiac death were determined for the whole follow up period. Results: Among 2770 eligible patients, 296 patients (10.6%) developed ischemic EKG changes during stress test but myocardial perfusion scan was normal. Out of 296 patients 181(61%) were male and mean age was 61.98 + 15 years. We were able to follow 280 patients (94.5%). During a mean follow-up of 4 years + 7 months, 8 patients (2.8 %) died, of which only one patient (0.3%) died due to cardiac cause. Angina occurred in 25patients (8.9%), myocardial infarction in 2 patients (0.7%) and one patient hospitalized with heart failure (0.3%). We performed coronary angiography of 16 patients (5.7%), of which nine underwent percutaneous transluminal coronary angioplasty (PTCA) and coronary artery bypass grafting (CABG) was done in three patients. Conclusion: The ischemic electrocardiographic changes during stress testing in patients with normal MPI are not associated with poor out come and the risk of cardiovascular events is relatively low for an intermediate follow up period. Continuous....

Lung Sestamibi Uptake on Myocardial Perfusion Imaging and Outcomes in Chronic Kidney Disease

<b><i>Background and Objectives:</i></b> In patients with CKD and end-stage kidney disease (ESKD), cardiac stress testing has low sensitivity and specificity for coronary disease. Alternate markers that are derived during the stress testing may enhance the predictive characteristic of stress testing. The objective was to examine the predictive characteristic of lung-to-heart ratio (LHR) in patients with CKD and ESKD. <b><i>Design, Setting, Participants, and Measurements:</i></b> Retrospective parallel cohort of ESKD and CKD not on dialysis (CKD-ND) who underwent stress testing with nuclear myocardial perfusion imaging utilizing sestamibi tracer and regadenoson. Stress LHR was calculated by the processing software and reported. Patients were analyzed by tertile of LHR (≤0.28, 0.29–0.32, ≥0.33). The primary outcome was a composite of all-cause mortality, hospitalization for myocardial infarction or unstable angina, or revascularization. <b><i>Results:</i></b> There were 144 CKD-ND and 145 ESKD patients. Patients with ESKD had greater comorbidity burden than CKD-ND. Stress tests were more often performed for pre-operative risk assessment among ESKD versus CKD-ND (53.8 vs. 5.6%, <i>p</i> &#x3c; 0.001). ESKD patients more likely had ischemia identified on stress testing (19.3 vs. 8.3%, <i>p</i> = 0.001). Mean LHR was 0.31 (Standard deviation – SD: 0.09) and was similar across CKD-ND stages and ESKD. Primary outcome in the lowest (23%) and highest (33.3%) LHR tertile was higher than the middle tertile (12.8%); <i>p</i> = 0.005. This finding was similar between CKD-ND and ESKD and persisted in multivariable analysis. <b><i>Conclusions:</i></b> LHR ≤0.28 and ≥0.33 are independently associated with higher risk for death in patients with CKD-ND and ESKD. Future studies are warranted to understand the association of extreme LHR values and outcomes in this high-risk population.

Incremental value of high-frequency QRS analysis for diagnosis and prognosis in suspected exercise-induced myocardial ischaemia

Aim: Exercise stress testing is used to detect myocardial ischaemia, but is limited by low sensitivity and specificity. The authors investigated the value of the analysis of high-frequency QRS components as a marker of abnormal depolarization in addition to standard ST-deviations as a marker of abnormal repolarization to improve the diagnostic accuracy. Methods and results: Consecutive patients undergoing bicycle exercise stress nuclear myocardial perfusion imaging were prospectively enrolled. Presence of myocardial ischaemia, the primary diagnostic endpoint, was adjudicated using MPI and coronary angiography. Automated high-frequency QRS analysis was performed in a blinded fashion. The prognostic endpoint was major adverse cardiac events (MACEs) during two years of follow-up. Exercise-induced ischaemia was detected in 147/662 patients (22%). The sensitivity of high-frequency QRS was similar to ST-deviations (46% vs. 43%, p=0.59), while the specificity was lower (75% vs. 87%, p<0.001). The combined use of high-frequency QRS and ST-deviations classified 59% of patients as ‘rule-out’ (both negative), 9% as ‘rule-in’ (both positive) and 32% in an intermediate zone (one test positive). The sensitivity for ‘rule-out’ and the specificity for ‘rule-in’ improved to 63% and 97% compared with ST-deviation analysis alone (both p<0.001). MACE-free survival was 90%, 80% and 42% in patients in the ‘rule-out’, intermediate and ‘rule-in’ groups ( p<0.001). After adjustment for age, gender, ST-deviations and clinical post-test probability of ischaemia, high-frequency QRS remained an independent predictor for the occurrence of MACEs. Conclusion: The use of high-frequency QRS analysis in addition to ST-deviation analysis improves the diagnostic accuracy during exercise stress testing and adds independent prognostic information.