Introduction A significant proportion of hospital admissions consist of patients with suspected acute coronary syndrome (ACS), a non-diagnostic ECG and a normal 12-h troponin who require further risk stratification. A recent prospective randomised controlled study in our institution has shown that stress echocardiography (SE) is superior and more cost-effective compared with exercise electrocardiography in the risk stratification of these patients. This is the first study to assess the feasibility, accuracy and safety of SE for risk stratification in this specific population of patients within a real-life UK district general hospital setting.
Methods and Results We evaluated 173 consecutive patients (mean age 60 ± 11 years) with at least two or more cardiac risk factors who presented with acute chest pain but a non-diagnostic ECG and a normal 12-h troponin. All patients underwent SE (97% dobutamine) within 24 h of admission and were followed up for myocardial infarction or death. A low-risk SE result was defined as the absence of any inducible wall motion abnormality (WMA) or the involvement of no more than one myocardial segment (16-segment model) at a minimum target heart rate of 85% of the age-adjusted maximum heart rate. A high-risk scan was defined as the occurrence of inducible WMA in two or more segments. An inconclusive result was defined as failure to reach the minimum target heart rate in the absence of inducible WMA. The population studied had a mean TIMI risk score of 2 (low–intermediate). Diagnostic SE images were obtained in all patients and transpulmonary contrast agent was used in 89 (52%) patients. There were no significant reported adverse events during SE. 161 patients (93%) had a low risk; six (3.5%) patients were high risk and six (3.5%) patients had an inconclusive scan result. Those with a low-risk scan were discharged after a median hospital length of stay of 26 h. All patients with a high-risk scan result underwent inpatient coronary angiography, which demonstrated two patients each with single, double and triple vessel disease. Of these patients, three subsequently underwent successful percutaneous coronary revascularisation. All 173 patients were followed up over a mean period of 12 months (range 8–18). Only one patient (0.6%) with a low-risk scan result was re-admitted with an acute myocardial infarction and died (fig 1). There were no other reported re-admissions for myocardial infarction or coronary revascularisation.
Conclusion For patients presenting with suspected ACS, a non-diagnostic ECG and a normal 12-h troponin, SE offers a safe, rapid and accurate method of risk stratification that is logistically feasible as part of an acute chest pain clinical management pathway within a secondary care hospital setting (fig 2).