CAN PATIENTS PRESENTING TO THE ED WITH CHEST PAIN WHO HAVE INTERMEDIATE-RISK HEART SCORES BE MANAGED AS OUTPATIENTS? A RETROSPECTIVE REVIEW OF TWO RAPID ACCESS CHEST PAIN CLINICS

Abstract

BACKGROUND The HEART score provides clinical recommendations for patients presenting to the emergency department (ED) with chest pain. The initial retrospective validation study suggested that intermediate-risk patients have a 11.6% risk of a major adverse cardiac event (MACE) at 6 weeks and should be admitted to hospital for further investigation and treatment. Although inpatient admission facilitates timely investigations and treatment, this is a resource-intensive process. This study examines whether intermediate HEART score patients can be safely managed on an outpatient basis through rapid access chest pain clinics (RACPC). METHODS AND RESULTS This retrospective observational study included all chest pain patients referred to RACPCs from the ED between January 2018 and April 2020 in Regina and Saskatoon, Saskatchewan. HEART scores for the study were recorded as the HEART score given by the ED physician, and if this was unavailable, study authors calculated the HEART score from available clinical information. The primary outcome was MACE, a composite measure of death, acute coronary syndrome (ACS), stroke, coronary angiography, and revascularization at 6 weeks in intermediate-risk patients. Secondary outcomes included the type of MACE, rate of MACE before RACPC and the most predictive component of the HEART score. Out of 1989 ED referrals, 817 were for intermediate-risk patients. 9.3% (n=104) intermediate-risk patients experienced a MACE at 6 weeks, with coronary angiography being the most common MACE. In intermediate-risk patients, 1.10% (n=9) of MACEs occurred before RACPC follow-up. With angiography excluded, 0.73% of intermediate-risk patients experienced a MACE before their RACPC visit. The components of the HEART score most predictive of MACE were troponin (OR 11.0, 95% CI: 3.7-32.3) and history (OR 5.3, 95% CI: 2.4-11.8). CONCLUSION Our results challenge existing recommendations that patients with intermediate-risk HEART scores should be admitted. Discharging patients from the ED for outpatient follow-up is associated with the risk of an undetected MACE. In intermediate-risk patients, the risk of MACE before RACPC follow-up was below the 2% acceptable miss threshold recommended by the American College of Emergency Physicians. Conventional literature considers angiography as a MACE, despite it being a desired therapeutic outcome. Excluding angiography further reduces the risk of MACE before RACPC follow-up in intermediate-risk patients. These events could be further minimized through more restrictive RACPC referral processes that allow only intermediate-risk patients to be referred, as numerous studies emphasize safe discharge of low-risk patients. Nonetheless, further studies are needed to validate the safety of this model and effect on downstream admissions and cost savings. The HEART score provides clinical recommendations for patients presenting to the emergency department (ED) with chest pain. The initial retrospective validation study suggested that intermediate-risk patients have a 11.6% risk of a major adverse cardiac event (MACE) at 6 weeks and should be admitted to hospital for further investigation and treatment. Although inpatient admission facilitates timely investigations and treatment, this is a resource-intensive process. This study examines whether intermediate HEART score patients can be safely managed on an outpatient basis through rapid access chest pain clinics (RACPC). This retrospective observational study included all chest pain patients referred to RACPCs from the ED between January 2018 and April 2020 in Regina and Saskatoon, Saskatchewan. HEART scores for the study were recorded as the HEART score given by the ED physician, and if this was unavailable, study authors calculated the HEART score from available clinical information. The primary outcome was MACE, a composite measure of death, acute coronary syndrome (ACS), stroke, coronary angiography, and revascularization at 6 weeks in intermediate-risk patients. Secondary outcomes included the type of MACE, rate of MACE before RACPC and the most predictive component of the HEART score. Out of 1989 ED referrals, 817 were for intermediate-risk patients. 9.3% (n=104) intermediate-risk patients experienced a MACE at 6 weeks, with coronary angiography being the most common MACE. In intermediate-risk patients, 1.10% (n=9) of MACEs occurred before RACPC follow-up. With angiography excluded, 0.73% of intermediate-risk patients experienced a MACE before their RACPC visit. The components of the HEART score most predictive of MACE were troponin (OR 11.0, 95% CI: 3.7-32.3) and history (OR 5.3, 95% CI: 2.4-11.8). Our results challenge existing recommendations that patients with intermediate-risk HEART scores should be admitted. Discharging patients from the ED for outpatient follow-up is associated with the risk of an undetected MACE. In intermediate-risk patients, the risk of MACE before RACPC follow-up was below the 2% acceptable miss threshold recommended by the American College of Emergency Physicians. Conventional literature considers angiography as a MACE, despite it being a desired therapeutic outcome. Excluding angiography further reduces the risk of MACE before RACPC follow-up in intermediate-risk patients. These events could be further minimized through more restrictive RACPC referral processes that allow only intermediate-risk patients to be referred, as numerous studies emphasize safe discharge of low-risk patients. Nonetheless, further studies are needed to validate the safety of this model and effect on downstream admissions and cost savings.