The HEART-GP strategy for ruling out acute coronary syndrome in out-of-hours primary care: a diagnostic accuracy trial protocol

BackgroundAcute coronary syndrome (ACS) is a life-threatening condition that must be rapidly identified to prevent morbidity and mortality. Differentiating ACS from benign conditions remains difficult in primary care settings due to non-specific and overlapping symptom profiles, and limited diagnostic resources. Current guidelines promote a low threshold for emergency department (ED) referral, resulting in referral rates of 40-70%. Despite this cautious approach, ACS cases are still missed, sometimes with serious consequences. The arrival of high-sensitivity troponin (hs-troponin) point-of-care testing (POCT) may enable safer, faster, and more efficient diagnosis in primary care settings. Methods and analysisThis multicenter prospective diagnostic accuracy trial evaluates the HEART-GP strategy, combining a single fingerstick hs-troponin test with clinical assessment and optional ECG. Adults ([≥]18 years) presenting with acute chest pain or discomfort to one of four participating Dutch OOH-PC centers are eligible. The primary outcome is the occurrence of major adverse cardiovascular events a composite of death, ACS, or urgent revascularization within six weeks. Diagnostic safety (sensitivity, negative predictive value) and efficiency (ED referral reduction) will be compared against standard care. Secondary analyses will assess the value of sex-specific cut-offs and integration with existing risk scores (HEART, INTERCHEST, Marburg Heart Score). Anticipated resultsWe anticipate that the HEART-GP strategy will demonstrate high diagnostic safety along with marked efficiency gains, with potential for reducing unnecessary ED referrals. If hs-POCT proves reliable, it could be implemented widely to improve the safety and efficiency of acute chest pain evaluation in pre-hospital care. Ethics and disseminationThe study was approved by the CCMO (CIV-NL-22-11-041231, 11-03-2022) and the Medical Research Ethics Committee (MREC) of the Amsterdam UMC (NL82428.000.22, 02-03-2023) and registered in the ISRCTN registry (ISRCTN11954040). Results will be disseminated through peer-reviewed journals, academic conferences, and stakeholder engagement to inform future diagnostic pathways in primary care. Strengths and limitations of this studyO_ST_ABSStrengthsC_ST_ABSO_LIAn innovative, pragmatic strategy for rapid rule-out of ACS C_LIO_LIHigh external validity due to prospective, multi-center, real-world OOH-primary care design C_LIO_LIIdentification of the optimal strategy of various risk stratification approaches using hs-troponin testing C_LIO_LIBlinded, independent adjudication of clinical outcomes C_LI LimitationsO_LIPowered for the composite MACE, but not for the individual components: death, ACS, or urgent coronary revascularization C_LIO_LIDespite the use of a (delayed) reference standard, complete avoidance of possible verification bias cannot be achieved C_LI