Predictive value of a 4-hour accelerated diagnostic protocol in patients with suspected ischemic chest pain presenting to an emergency department

ABSTRACT

Currently recommended risk stratification protocols for suspected ischemic chest pain in the emergency department [ED] includes point-of-care availability of exercise treadmill/nuclear tests or CT coronary angiograms. These tests are not widely available for most of the ED's. This study aims to prospectively validate the safety of a predefined 4-hour accelerated diagnostic protocol [ADP] using chest pain, ECG, and troponin T among suspected ischemic chest pain patients presenting to an ED of a tertiary care hospital in Oman. One hundred and thirty-two patients aged over 18 years with suspected ischemic chest pain presenting within 12 hours of onset along with normal or non-diagnostic first ECG and negative first troponin T [<0.010 microg/l] were recruited from September 2008 to February 2009. Low-probability acute coronary syndrome [ACS] patients at 4-hours defined as absent chest pain and negative ECG or troponin tests were discharged home and observed for 30-days for major adverse cardiac events [MACE] [Group I negative ADP]. High-probability ACS patients at 4-hours were defined by recurrent or persistent chest pain, positive ECG or troponin tests and were admitted and observed for in-hospital MACE [Group II positive ADP]. One hundred and thirty-two patients were recruited and 110 patients completed the study. The overall 30-day MACE in this cohort was 15% with a mortality of less than 1%. 30-days MACE occurred in 8/95 of group I patients [8.4%] and 9/15 of the in-hospital MACE patients in group II. The ADP had a sensitivity of 52% [95% CI 0.28-0.76], specificity of 93% [0.85-0.97], a negative predictive value of 91% [0.83-0.96], a positive predictive value of 60% [0.32-0.82], negative likelihood ratio of 0.5 [0.30-0.83] and a positive likelihood ratio of 8.2 [3.3-20] in predicting MACE. A 4-hour ADP using chest pain, ECG, and troponin T had high specificity and negative predictive value in predicting 30-day MACE among low probability ACS patients discharged from ED. However, 30-day MACE in ADP negative patients was relatively high in contrast to guideline recommendations. Hence, there is a need to establish ED chest pain unit and adopt new protocols especially adding a point-of-care exercise treadmill test in the ED