Khim Leng Tong

Detection of Coronary Stenoses at Rest With Myocardial Contrast Echocardiography

Background—We hypothesized that autoregulatory changes in arteriolar blood volume (aBV) that develop distal to a stenosis can be measured with myocardial contrast echocardiography, allowing coronary stenosis detection at rest without recourse to stress. Methods and Results—Patients with varying degrees of coronary artery stenosis on quantitative angiography underwent high-mechanical-index myocardial contrast echocardiography at 15 Hz to allow measurement of phasic changes in aBV in large intramyocardial vessels using either Definity (group 1; n=22) or Imagent (group 2; n=22). Progressive increases in the background-subtracted systolic/diastolic aBV signal ratio were noted between each level (none, mild [<50%], moderate [50% to 75%], and severe [>75%]) of stenosis severity for both group 1 (0.09±0.13, 0.13±0.08, 0.58±0.22, and 0.77±0.40; P<0.001) and group 2 (0.10±0.05, 0.27±0.18, 0.39±0.28, and 0.74±0.37; P<0.0001) patients. A systolic/diastolic aBV signal ratio of >0.34 provided a sensitivity and specificity of 80% and 71%, respectively, for the detection of >75% coronary stenosis in group 1 patients, whereas a ratio of >0.43 provided a sensitivity and specificity of 89% and 74%, respectively, for the detection of >75% stenosis in group 2 patients. Conclusions—Both the presence and severity of a physiologically significant coronary stenosis can be detected at rest by measuring the increase in aBV on myocardial contrast echocardiography that occurs distally to the stenosis without recourse to any form of stress.

A predictive instrument using contrast echocardiography in patients presenting to the emergency department with chest pain and without ST-segment elevation.

OBJECTIVE Risk stratification of patients presenting to the emergency department (ED) with suspected cardiac chest pain (CP) and an undifferentiated electrocardiogram (ECG) is difficult. We hypothesized that in these patients a risk score incorporating clinical, ECG, and myocardial contrast echocardiography (MCE) variables would accurately predict adverse events occurring within the next 48 hours. METHODS Patients with CP lasting for 30 minutes or more who did not have ST-segment elevation on the ECG, were enrolled. Regional function (RF) and myocardial perfusion (MP) were assessed by MCE. A risk model was developed in the initial 1166 patients (cohort 1) and validated in subsequent 720 patients (cohort 2). Any abnormality or ST changes on ECG (odds ratio [OR] 2.5; 95% confidence interval [CI], 1.4-4.5, P = .002, and OR 2.9, 95% CI, 1.7-4.8, P < .001, respectively), abnormal RF with normal MP (OR 3.5, 95% CI, 1.8-6.5, P < .001), and abnormal RF with abnormal MP (OR 9.6, 95% CI, 5.8-16.0, P < .001) were found to be significant multivariate predictors of nonfatal myocardial infarction or cardiac death. RESULTS The estimate of the probability of concordance for the risk model was 0.82 for cohort 1 and 0.83 for cohort 2. The risk score in both cohorts stratified patients into 5 distinct risk groups with event rates ranging from 0.3% to 58%. CONCLUSION A simple predictive instrument has been developed from clinical, ECG, and MCE findings obtained at the bedside that can accurately predict events occurring within 48 hours in patients presenting to the ED with suspected cardiac CP and an ECG that is not diagnostic for acute ischemic injury. Its application could enhance care of patients with CP in the ED. For instance, patients with a risk score of 0 could be discharged from the ED without further workup. However, this needs to be validated in a multicenter study.

COMPARING UTILIZATION OF TIMI RISK INDEX VERSUS KILLIP CLASS AT PRESENTATION IN DETERMINING THE NEED OF ADMISSION TO CORONARY CARE UNIT FOR ACUTE ST ELEVATION MYOCARDIAL INFARCTION PATIENT AFTER SUCCESSFUL PRIMARY PERCUTANEOUS CORONARY INTERVENTION: SINGLE CENTRE STUDY

Background: With the ever-increasing number of acutely ill patients with cardiac disease that need intensive monitoring and limited resources in coronary care unit (CCU), there is a need to ensure appropriate admission to CCU. Studies have shown that Killip 1 patients who had successful primary percutaneous coronary intervention (PPCI) for ST Elevation Myocardial Infarction (STEMI) can be admitted safely to a step-down unit. However, Killip class was a subjective assessment. We attempt to compare TIMI risk index {TRI = [heart rate X (age/10)2]/systolic blood pressure} versus Killip Class at presentation in determining the need of admission to CCU for STEMI patient after successful PPCI. TRI was a robust predictor (for STEMI patients on irst arrival in hospital) and high discriminatory capacity of in-hospital events in each of the ive risk subgroups.