Acute Coronary Syndrome At First Contact In Primary Care: Women, Diabetes, And The Safety Of Rapid ECG High Sensitivity Troponin Pathways

BackgroundAcute coronary syndrome at first contact in primary care must be recognised rapidly and safely--especially in women and in adults with diabetes, who more often present without classic chest pain and are at risk of under-triage. We synthesised evidence on symptom constellations and triage strategies--rapid electrocardiogram, high-sensitivity cardiac troponin pathways, and primary-care risk tools--that reduce missed or late recognition of acute coronary syndrome. MethodsTargeted review (Jan 1, 2007-May 31, 2025) of prospective cohorts, diagnostic or implementation studies, risk-tool derivations and validations, telephone-triage studies, and contemporary guidelines relevant to first-contact primary care (office, urgent or emergency primary care, and out-of-hours services). Prespecified outcomes were missed acute coronary syndrome, 30-day major adverse cardiac events, time to electrocardiogram, time to troponin and decision, emergency-department transfer or admission, length of stay, and diagnostic performance (sensitivity, specificity, negative and positive predictive value). Risk of bias was assessed with Quality Assessment of Diagnostic Accuracy Studies-2, Newcastle-Ottawa Scale, and Risk of Bias 2, and certainty of evidence with Grading of Recommendations, Assessment, Development and Evaluation. FindingsAcross 18 sources, symptom clusters alone were insufficient to safely rule out acute coronary syndrome; history-based rules showed heterogeneous sensitivity and are best used to structure history and trigger testing. Rapid electrocardiogram (with repeats when concern persists) and high-sensitivity cardiac troponin algorithms provided the greatest diagnostic safety. Ambulatory implementations of assay-specific strategies achieved very high negative predictive values (approximately 99-100%) for rule-out in low-risk populations and accelerated disposition; an emergency primary-care deployment of the European Society of Cardiology 0/1-hour high-sensitivity troponin pathway ruled out about 64% at 1 hour, yielded a conclusive decision for about 77% by 4 hours, and reduced length of stay by roughly 2.2 hours. Safety margins were lower in patients with known coronary artery disease (negative predictive value about 96-98%) and the rule-out fraction was smaller, supporting more conservative thresholds, brief observation, or adjunctive clinical risk scoring. Telephone and out-of-hours case-control data linked non-retrosternal descriptors and system factors to missed acute coronary syndrome, arguing for up-triage to in-person electrocardiogram and troponin testing or emergency medical services transfer. InterpretationFor adults first assessed in primary care--particularly women and people with diabetes--a protocolised pathway (electrocardiogram within minutes, serial high-sensitivity troponin using assay-specific delta thresholds, and clear escalation) offers high rule-out safety with faster, more equitable care. Known coronary artery disease is a caution zone, warranting stricter discharge thresholds or extended observation. Health systems should invest in clinic electrocardiogram access, point-of-care high-sensitivity troponin where laboratory turnaround is slow, emergency-medical-services-first scripts, and routine audit (time to electrocardiogram and troponin, rule-out at 1 and 4 hours, emergency-department transfer, and 30-day major adverse cardiac events) stratified by sex, diabetes status, and coronary artery disease. RESEARCH IN CONTEXTO_ST_ABSEvidence before this studyC_ST_ABSWe searched MEDLINE (via PubMed), Embase, and Web of Science from Jan 1, 2007, to May 31, 2025, using terms for acute coronary syndrome (ACS)/chest pain, primary care/general practice/out-of-hours services, women/sex differences, diabetes, high-sensitivity cardiac troponin (hs-cTn; 0/1-hour and very-low strategies), telephone triage, and primary-care risk scores (Marburg Heart Score, INTERCHEST, HEART/HEAR). We hand-searched guideline repositories and reference lists. Three signals consistently emerged: (1) guidelines endorse rapid electrocardiogram (ECG) and hs-cTn-based pathways; (2) symptom clusters alone--particularly in women and people with diabetes--are insufficient to rule out ACS; and (3) primary-care data are sparse and heterogeneous, with safety concerns in known coronary artery disease (CAD) when accelerated rule-out algorithms are used. Few studies linked findings to operational metrics important at the primary-care front door (time-to-ECG/hs-cTn, rule-out proportions, length of stay [LOS]). Added value of this studyWe integrate first-contact primary-care evidence across 18 sources into a single, implementable pathway centered on rapid ECG, assay-specific hs-cTn strategies (0/1-hour or single very-low when symptom onset [≥]3 h), and explicit escalation thresholds. We foreground women and adults with diabetes, quantify rule-out safety including the known-CAD caveat, and pair clinical accuracy with operational outcomes (time-to-test, rule-out at 1/4 h, emergency department transfers, LOS). We provide a concise summary table and figure plus an audit set that clinicians can deploy immediately, alongside formal risk-of-bias and GRADE certainty judgments. Implications of all the available evidencePrimary care can safely accelerate ACS evaluation by pairing ECG within 10 minutes and hs-cTn algorithms with conservative thresholds in known CAD and proactive escalation for non-chest presentations common in women and people with diabetes (e.g., dyspnea, epigastric discomfort, unusual fatigue). Health systems should invest in clinic ECG access, point-of-care hs-cTn where laboratory turnaround is slow, emergency medical services (EMS)-first triage scripts, and routine audit of time-to-ECG/hs-cTn, rule-out proportions, emergency department transfers, and 30-day major adverse cardiac events (MACE) stratified by sex, diabetes, and CAD. Research priorities include prospective, consecutive primary-care cohorts with adjudicated 30-day outcomes, pragmatic trials of point-of-care hs-cTn, decision support tailored to known CAD, and cluster-randomized improvements to telephone/virtual triage.