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

Patient- and procedure-related factors in the pathophysiology of perioperative myocardial infarction/injury

Perioperative myocardial infarction/injury (PMI) is a frequent, often missed and incompletely understood complication of noncardiac surgery. The aim of this study was to evaluate whether patient- or procedure-related factors are more strongly associated to the development of PMI in patients undergoing repeated noncardiac surgery.; In this prospective observational study, patient- and procedure-related factors were evaluated for contribution to PMI using: 1) logistic regression modelling with PMI as primary endpoint, 2) evaluation of concordance of PMI occurrence in the first and the second noncardiac surgery (surgery 1 and 2). and 3) the correlation of the extent of cardiomyocyte injury quantified by high-sensitivity cardiac troponin T between surgery 1 and 2. The secondary endpoint was all-cause mortality associated with PMI reoccurrence in surgery 2.; Among 784 patients undergoing repeated noncardiac surgery (in total 1'923 surgical procedures), 116 patients (14.8%) experienced PMI during surgery 1. Among these, PMI occurred again in surgery 2 in 35/116 (30.2%) patients. However, the vast majority of patients developing PMI during surgery 2 (96/131, 73.3%) had not developed PMI during surgery 1 (phi-coefficient 0.150, p < 0.001). The correlation between the extent of cardiomyocyte injury occurring during surgery 1 and 2 was 0.153. All-cause mortality following a second PMI in surgery 2 was dependent on time since surgery (adjusted hazard ratio 5.6 within 30 days and 2.4 within 360 days).; In high-risk patients, procedural factors are more strongly associated with occurrence of PMI than patient factors, but patient factors are also contributors to the occurrence of PMI

Obesity paradox and perioperative myocardial infarction/injury in non-cardiac surgery

The impact of obesity on the incidence of perioperative myocardial infarction/injury (PMI) and mortality following non-cardiac surgery is not well understood.; We performed a prospective diagnostic study enrolling consecutive patients undergoing non-cardiac surgery, who were considered at increased cardiovascular risk. All patients were screened for PMI, defined as an absolute increase from preoperative to postoperative sensitive/high-sensitivity cardiac troponin T (hs-cTnT) concentrations. The body mass index (BMI) was classified according to the WHO classification (underweight 40 kg/m; 2; ). The incidence of PMI and all-cause mortality at 365 days, both stratified according to BMI.; We enrolled 4277 patients who had undergone 5413 surgeries. The median BMI was 26 kg/m; 2; (interquartile range 23-30 kg/m; 2; ). Incidence of PMI showed a non-linear relationship with BMI and ranged from 12% (95% CI 9-14%) in obesity class I to 19% (95% CI 17-42%) in the underweight group. This was confirmed in multivariable analysis with obesity class I. showing the lowest risk (adjusted OR 0.64; 95% CI 0.49-0.83) for developing PMI. Mortality at 365 days was lower in all obesity groups compared to patients with normal body weight (e.g., unadjusted OR 0.54 (95% CI 0.39-0.73) and adjusted OR 0.52 (95% CI 0.38-0.71) in obesity class I).; Obesity class I was associated with a lower incidence of PMI, and obesity in general was associated with a lower all-cause mortality at 365 days