Table 5. Potential factors associated with guideline adherence.

Type of factor			Factor					Main results†	Guideline recommendations‡∞
									I		II			III						IV
Patient			Demographics
			Age					Elderly patients were less likely to receive acute aspirin, BB, heparin [34] and GP IIb/IIIa inhibitors [28,32], CA ≤48 h or in-hospital [24,49], statin [34], and all guideline recommended therapies (i.e. ACE, aspirin, BB, statin) [64] at discharge than younger patients Patients’ aged between 55 years and 74 years were less likely to receive acute BB [29] than patients below 55 years or of 75 years and older	↓ ↓					↓						↓
			Gender					Female patients were less likely to receive acute BB [29] and GP IIb/IIIa inhibitors [28,32], to receive CA ≤48 h or in-hospital [24,56], and to receive all guideline recommended discharge therapies (i.e. ACE, aspirin, BB, statin) [64] than male patients	↓					↓						↓
			Race					Patients of white race were more likely to receive acute GPIIb/IIIa inhibitors [28,32], CA ≤48 h [24], and clopidogrel at discharge [30] than patients of a non-white race	↑					↑						↑
			Clinical factors
			Angina pectoris					Patients with a history of angina pectoris were more likely to receive all guideline recommended discharge therapies (i.e. ACE, aspirin, BB, statin), than patients without a history of angina pectoris [64]												↑
			CHF					Patients with chronic heart failure were less likely to receive acute antiplatelet therapy (e.g. clopidogrel) [53], BB [29] and GPIIb/IIIa inhibitors [28], to receive CA ≤48 h [24], and all guideline recommended discharge therapies (i.e. ACE, aspirin, BB, statin) [64], than patients without chronic heart failure	↓					↓						↓
			PAD					Patients with PAD were more likely to be prescribed with clopidogrel at discharge, than patients without PAD [30]												↑
			Prior PCI					Patients with a prior PCI were more likely to receive acute antiplatelet therapy (e.g. clopidogrel) [53] and GPIIb/IIIa inhibitors [32], to receive CA ≤48 h [24], and to receive clopidogrel at discharge [30], than patients without a PCI in their medical history Patients with a prior PCI were less likely to be treated with acute BB, than patients without a PCI in their medical history [29]	↑ ↓					↑						↑
			Prior CABG					Patients with a prior CABG were less likely to receive acute GP IIb/IIIa inhibitors [28], and to receive CA ≤48 h [24], than patients without a CABG in their medical history Patients with a prior CABG were more likely to be prescribed with clopidogrel at discharge, than patients without a CABG in their medical history [30]	↓					↓						↑
			Prior MI					Patients with a prior MI were more likely to receive clopidogrel [30] and all guideline recommended therapies (i.e. ACE, aspirin, BB, statin) [64] at discharge, than patients without a MI in their medical history Patients who had a prior MI were less likely to receive acute GPIIb/IIIa inhibitors [28], and CA ≤48 h, than patients without a MI in their medical history [24]	↓					↓						↑
			Prior clopidogrel use					Patients who used clopidogrel before hospitalization were more likely to receive clopidogrel at discharge, than patients who did not use clopidogrel before hospitalization [30, 57]												↑
			Prior BB use					Patients who used BB before hospitalization were more likely to receive acute BB, than patients who did not use BB before hospitalization [29]	↑
			Prior heparin use					Patients who used heparin before hospitalization were less likely to be prescribed with clopidogrel at discharge, than patients who did not use heparin before hospitalization [30]												↓
			Prior stroke					Patients with a prior stroke were less likely to receive acute GP IIb/IIIa inhibitors [28], to receive CA ≤48 h [24], and all guideline recommended therapies (i.e. ACE, aspirin, BB, statin) [64] at discharge, than patients without a stroke in their medical history Patients with a prior stroke were more likely to receive clopidogrel at discharge [57], than patients without a stroke in their medical history	↓					↓						↓ ↑
			BMI					Patients with a high BMI were more likely to receive CA ≤48 h [24], and more likely to have a risk score documented in their medical chart [50], than patients with a normal BMI			↑			↑
			CAD risk factors					Patients with two or more risk factors for CAD were more likely to receive clopidogrel at discharge, than patients with one or no risk factors for CAD [57]												↑
Type of factor		Factor					Main results†			Guideline recommendations‡∞
										I			II				III					IV
Patient		Clinical factors
		Diabetes mellitus					Patients with diabetes mellitus were less likely to receive acute aspirin [34], and to receive CA ≤48 h or in-hospital [24,49], than patients without diabetes mellitus Patients with diabetes mellitus were more likely to receive clopidogrel [30] and all guideline recommended therapies (i.e. ACE, aspirin, BB, statin) [64] at discharge, than patients without diabetes mellitus			↓							↓					↑
		EF <40%					Patients with an EF <40% were less likely to be prescribed with clopidogrel at discharge, than patients without an EF <40% [30]															↓
		Family history of CAD					Patients with a positive family history for CAD were more likely to receive acute BB [29] and GP IIb/IIIa inhibitors [28], and CA ≤48 h [24] than patients with a negative family history of CAD			↑							↑
		Heart failure (acute)					Patients with acute heart failure were less likely to receive acute aspirin, heparin [34], GP IIb/IIIa inhibitors [28] and BB [29,34], to receive CA ≤48 h [24], and less likely to receive all guideline recommended discharge therapies (i.e. ACE, aspirin, BB, statin)[64], than patients without acute heart failure. They were also less likely to have a risk score documented in their medical chart [50] Patients with acute heart failure were more likely to be prescribed with ACE at discharge, than patients without acute heart failure [34]			↓			↓				↓					↓ ↑
		Hypercholesterolemia					Patients with hypercholesterolemia were more likely to receive acute BB [29] and GPIIb/IIIa inhibitors [28], to receive CA ≤48 h [24], and to receive clopidogrel at discharge [30], than patients without hypercholesterolemia			↑							↑					↑
		Hypertension					Patients with a history of hypertension were more likely to receive acute GPIIb/IIIa inhibitors [28], and to receive all guideline recommended discharge therapies (i.e. ACE, aspirin, BB, statin) [64], than patients without a history of hypertension			↑												↑
		Kidney failure					Patients with kidney failure were less likely to receive acute aspirin, heparin [34], BB [29] and GPIIb/IIIa inhibitors [28], to receive CA ≤48 h [24], and to receive aspirin and ACE at discharge [34], than patients without kidney failure			↓							↓					↓
		NSTEMI					NSTEMI patients were less likely to receive clopidogrel at discharge than patients with UA [57], but were more likely to have a risk score documented in their medical chart [50]						↑									↓
		Risk status (GRACE)					Patients with a high risk status are less likely to receive acute antiplatelet therapy [53] and other acute medications [56], to receive CA, and appropriate discharge medications [56] compared to patients with a low risk status			↓							↓					↓
		Smoking					(Recent) smokers were more likely to receive acute GPIIb/IIIa inhibitors [28,32], CA ≤48 h [24], and clopidogrel at discharge [30], than non-smokers (Recent) smokers were also more likely to have a risk score documented in their medical chart than non-smokers [50]			↑			↑				↑					↑
		Bleeding					Patients with a major bleeding in their medical history were less likely to be treated with antiplatelet therapy (e.g. clopidogrel) [53] or to receive clopidogrel at discharge [30], than patients without a major bleeding			↓												↓
		Hemodynamics
		Blood pressure					Patients with a high blood pressure at admission were more likely to receive acute BB [29], CA ≤48 h [24], and clopidogrel at discharge [30] than patients with a normal blood pressure at admission			↑							↑					↑
		Heart rate					Patients with a high heart rate were less likely to receive acute BB [29] and GP IIb/IIIa inhibitors [28], to receive CA ≤48 h [24], and to receive clopidogrel at discharge [30] than patients with a normal heart rate at admission. They were also less likely to have a risk score documented in their medical chart [50]			↓			↓				↓					↓
		Cardiac arrest / resuscitation					Patients presenting with cardiac arrest or who were resuscitated at hospital-admission were less likely to be treated with acute antiplatelet therapy (e.g. clopidogrel) [53], and less likely to have a risk score documented in their medical chart [50], than patients not presenting with cardiac arrest or being resuscitated in hospital			↓			↓
		Cardiogenic shock					Patients presenting with cardiogenic shock were less likely to receive all guideline recommended discharge therapies (i.e. ACE, aspirin, BB, statin), than patients without cardiogenic shock [64]															↓
Type of factor				Factor		Main results†						Guideline recommendations‡∞
												I			II				III				IV
Patient				Laboratory results
				Cardiac markers (e.g. troponin, CK-MB, CK)		Patients with positive cardiac markers were more likely to receive acute aspirin, BB, heparin [34] and GP IIb/IIIa inhibitors [28], to receive CA ≤48 h or in-hospital [24,37,49], and ACE, aspirin, BB, Statin [34], clopidogrel at discharge [30] than patients with normal cardiac markers levels						↑							↑				↑
				HB		Patients with HB levels of 9g/dL or lower were either less likely to receive clopidogrel at discharge [30] or more likely to receive clopidogrel at discharge [57] than patients with normal HB levels																	↑ ↓
				Electrocardiogram findings
				Transient ST elevation		Patients with transient ST elevation were more likely to receive acute aspirin [34], BB [29,34] and heparin [34], to receive CA ≤48 h [24], and to be discharged with aspirin, BB and ACE [34] than patients without such deviations on the electrocardiogram						↑							↑				↑
				ST depression		Patients with ST depression were more likely to receive acute aspirin [34], BB [29,34], heparin [34] and GP IIb/IIIa inhibitors [28], and to receive CA ≤48 h or in-hospital [24, 49] and to be discharged with ACE, aspirin, and BB [34] than patients without such deviations on the electrocardiogram						↑							↑				↑
				Atrial fibrillation		Patients with atrial fibrillation were less likely to receive all guideline recommended discharge therapies (i.e. ACE, aspirin, BB, statin), than patients without such deviation on the electrocardiogram [64]																	↓
				Invasive diagnostic procedures
				CA ≤24 h		Patients catheterized within the first 24 h after admission were more likely to be treated with antiplatelet therapy (e.g. clopidogrel), than patients that were not catheterized within the first 24 h after admission [53]						↑
				In-hospital CA		Patients receiving CA in-hospital were more likely to receive antiplatelet therapy (e.g. clopidogrel) [53], and to receive clopidogrel at discharge [30] than patients not receiving CA in-hospital						↑											↑
				Other
				Insurance		Patients with medicare or no insurance were less likely to receive acute BB [29] and GP IIb/IIIa inhibitors [28,32], and to receive CA ≤48 h than patients with private insurance [24] Patients with self-insurance were more likely to receive acute BB [29], but less likely to receive acute GP IIb/IIIa inhibitors [28], than patients with private insurance						↓ ↑							↓
				Time of presentation		Patients presenting at hospital during off-hours (i.e. between 5 pm to 7 am or in weekends) were less likely to receive CA ≤48 h, than patients presenting between during the week hours between 7 am to 5 pm [24]													↓
Organization				PCI facilities		Patients treated at hospitals with PCI facilities were more likely to receive CA ≤48 h, than patients treated in hospitals without such facilities [24]													↑
				CABG facilities		Patients treated at hospitals with surgical facilities were more likely to receive CA ≤48 h [24], and be among centers with the highest adherence rates regarding acute and discharge therapies [19] than patients treated at hospitals without surgical facilities						↑							↑				↑
				Catheterization facilities		Patients admitted to hospitals with onsite catheterization facilities were less likely to be treated with antiplatelet therapy (e.g. clopidogrel), than patients admitted to hospitals without such facilities [53] Patients admitted to hospitals with onsite catheterization facilities were more likely to receive CA, than patients treated in hospitals without such facilities [56]						↓							↑
				Cardiology care		Patients cared for by cardiologists were more likely to receive acute aspirin [34], BB [29,34], heparin [34] and GP IIb/IIIa inhibitors [28], to receive CA ≤48 h or in-hospital [24,56], and ACE, aspirin, BB, statin at discharge [34], and to be among centers with the highest adherence rates regarding acute and discharge therapies [19], than patients treated by other specialists						↑							↑				↑
Type of factor	Factor				Main results†											Guideline recommendations‡∞
																I		II			III			IV
Organization	Geographical location				Patients from the Northeast region (USA) were less likely to receive CA ≤48 h than patients in the south region [24] Patients from the Midwest/west region (USA) were more likely to receive CA ≤48 h than patients in the south region [24] Patients treated in Europe, Australia, New-Zealand and Canada were more likely to receive all guideline recommended discharge therapies (i.e. ACE, aspirin, BB, statin) than patients treated in North America [64] Patients treated in Argentina and Brazil were less likely to receive all guideline recommended discharge therapies (i.e. ACE, aspirin, BB, statin) than patients treated in the North America [64]																↓ ↑			↑ ↓
	Nr. of beds				Patients treated in hospitals with higher numbers of hospital beds were less likely to receive CA ≤48 h, than patients treated in hospital with lower number of hospital beds [24]																↓
	Accreditation				Patients treated at SCPC accredited hospitals were more likely to receive acute aspirin and BB, than patients not treated in such hospitals [25]											↑
	Hospitals’ teaching status				Patients treated at teaching hospitals were more likely to receive acute BB [29] and to receive CA in-hospital [49], than patients treated in non-teaching hospitals Patients treated at teaching hospitals were less likely to receive CA ≤48 h, than patients treated in non-teaching hospitals [24]											↑					↑ ↓
	Quality of MI care				Patients treated at hospitals with lower quality measures of MI care were less likely to receive clopidogrel at discharge, than patients treated at hospitals with higher quality of care measures of MI care [30]																			↓
Abbreviations: ACE, angiotensin-converting-enzyme inhibitor; BB, beta-blocker; BMI, body mass index; CA, coronary angiography; CABG, coronary artery bypass grafting; CAD, coronary artery disease; CHF, chronic heart failure; EF, ejection fraction; GP IIb/IIIa, Glycoprotein IIb/IIIa receptor inhibitors; GRACE, global registry of acute coronary events; HB, hemoglobin; MI, myocardial infraction; NSTEMI, non-ST-elevation myocardial infarction; PAD, peripheral artery disease; PCI, percutaneous coronary intervention; SCPC accreditation, society of cardiovascular patient care accreditation; UA, unstable angina. †Factors significantly (p≤0.05) associated with guideline adherence in multivariable analysis. ‡class I guideline recommendation: I = acute pharmacological care (<24 h after admission), II = risk stratification, III = invasive procedures, IV = discharge pharmacological care. ↑= higher adherence, ↓ = lower adherence. ∞ All factors are derived from studies studying adherence to the ACC/AHA guidelines, except Vikman 2003 (49) & Engel 2015 (50) who studied adherence to the ESC guidelines.