1,329 calculators and references across 60 specialties, with each tool type shown up front.
MRI-LGE Extent (% LV Mass Fibrosis): Comprehensive Explanation and Clinical Context This calculator estimates the proportion of myocardial fibrosis (late gadolinium enhancement, LGE) relative to total left ventricular (LV) mass using cardiac MRI data: %LGE = (LGE mass / LV mass) × 100. When input volumes are provided, they are converted to grams assuming a myocardial density of 1.05 g/mL. LGE reflects focal myocardia
MUSTT Score (VT Inducibility): Explanation and Clinical Context The MUSTT (Multicenter Unsustained Tachycardia Trial) Score is designed to estimate the risk of arrhythmic events and sudden cardiac death in patients with prior myocardial infarction, left ventricular dysfunction, and non-sustained ventricular tachycardia. It incorporates key clinical parameters: age, left ventricular ejection fraction, NYHA functional
mWHO Classification of Maternal Cardiovascular Risk (2022 ESC): Explanation and Clinical Context The mWHO classification stratifies women with pre-existing cardiovascular disease according to the risk of maternal mortality and morbidity during pregnancy. It is a widely accepted tool in cardiology and obstetrics for counseling, planning, and monitoring pregnant women with cardiac conditions. - mWHO I indicates no dete
MYH7/MYBPC3 Mutation Severity Score - Explanation, clinical context and references This research model score aggregates genotype (gene and variant class), allele status (heterozygous vs compound/biallelic), family history of sudden cardiac death, age at diagnosis, maximal left ventricular wall thickness, arrhythmic markers (non-sustained ventricular tachycardia), recent unexplained syncope, left ventricular outflow tract
Myocardial Conduction Abnormality Score (MCAS): Explanation and Clinical Context The Myocardial Conduction Abnormality Score (MCAS) is a clinical tool developed to estimate the risk of conduction disturbances in patients with underlying cardiac disease, particularly those with prior myocardial infarction or age-related conduction changes. The score combines key variables including age, QRS duration, PR interval, pres
Myocardial Edema Ratio (MER): Explanation and Clinical Context The Myocardial Edema Ratio (MER) is a quantitative index derived from T2-weighted cardiac MRI images, calculated as the ratio of myocardial signal intensity (SI) to skeletal muscle SI. It is used to identify myocardial edema, commonly observed in acute myocardial injury such as myocarditis, acute myocardial infarction, or inflammatory cardiomyopathies. A
Myocardial Flow Reserve (MFR): Explanation and Clinical Context Myocardial Flow Reserve (MFR) is a quantitative index derived from positron emission tomography (PET) myocardial perfusion imaging, calculated as the ratio of hyperemic (stress) myocardial blood flow (MBF) to resting MBF. An MFR value below 2.0 is considered abnormal and reflects impaired coronary vasodilator capacity, which may result from epicardial co
Myocardial Injury after Noncardiac Surgery (MINS): Explanation and Clinical Context MINS refers to myocardial injury occurring within 30 days after noncardiac surgery, attributed to ischemic mechanisms and detected by postoperative cardiac troponin elevation. It is common, often clinically silent, and independently associated with short-term and long-term mortality. The preoperative model used here estimates i
Myocardial Perfusion Index (MPI): Explanation and Clinical Context The Myocardial Perfusion Index (MPI) quantifies the ratio of myocardial blood flow during stress to resting myocardial blood flow, serving as a non-invasive marker of coronary microvascular function and myocardial perfusion reserve. An MPI value near 2.0–3.0 is generally considered normal, reflecting adequate perfusion reserve. Reduced MPI values indi
Myocardial Protection Risk Index: Explanation and Clinical Context The Myocardial Protection Risk Index (MPRI) is a validated tool designed to estimate perioperative risk of myocardial injury and adverse outcomes during cardiac surgery. It integrates clinical variables including age, left ventricular ejection fraction, history of previous myocardial infarction, urgency of surgery, diabetes mellitus, and renal functio
Myocardial Salvage Score (MSS): Explanation and Clinical Context The Myocardial Salvage Score (MSS) quantifies the proportion of myocardium saved from infarction after coronary artery bypass grafting (CABG) or reperfusion therapy. It is calculated using the formula: MSS (%) = [(Area at Risk - Infarct Size) / Area at Risk] × 100 Where Area at Risk (AAR) represents the myocardium initially jeopardized by ischemia, and
Calculate Global Longitudinal Strain (GLS), Global Circumferential Strain (GCS), and Global Radial Strain (GRS) Myocardial Strain (GLS, GCS, GRS): Comprehensive Explanation and Clinical Context Myocardial strain quantifies myocardial deformation as a percentage change from the end-diastolic state. Global Longitudinal Strain (GLS) reflects the shortening of subendocardial longitudinal fibers and is reported as a negat
Myocardial Strain MRI (Feature Tracking, FT) : Explanation and Clinical Context Myocardial strain imaging using cardiac MRI feature tracking (FT) allows non-invasive quantification of myocardial deformation in three directions: longitudinal (GLS), circumferential (GCS), and radial (GRS). It provides early detection of subclinical myocardial dysfunction even when left ventricular ejection fraction (LVEF) is preserved.
Myocardial Work Efficiency Index (MWEI): Explanation and Clinical Context The Myocardial Work Efficiency Index (MWEI) is a novel, non-invasive echocardiographic parameter derived from left ventricular (LV) pressure–strain loops. It integrates LV deformation (strain) and afterload to evaluate the energy efficiency of myocardial contraction. The index is calculated as the ratio between Global Constructive Work (GCW)—th
Myocarditis Severity Index (MRI-based): Explanation and Clinical Context The Myocarditis Severity Index (MSI) is a composite score derived from key cardiac MRI parameters, including Left Ventricular Ejection Fraction (LVEF), T2 Mapping, and Late Gadolinium Enhancement (LGE). This index aids in assessing the severity of myocarditis and predicting clinical outcomes. A higher MSI indicates greater myocardial inflammatio
NAFLD Fibrosis Score (NFS): Explanation and Clinical Context The NAFLD Fibrosis Score is a non-invasive scoring system designed to estimate the likelihood of advanced fibrosis in patients with non-alcoholic fatty liver disease (NAFLD). It incorporates readily available clinical parameters including age, BMI, impaired fasting glucose/diabetes, AST/ALT ratio, platelet count, and albumin level. The resulting score strat
Age BMI Impaired Fasting Glucose or Diabetes Select Yes No AST ALT Platelet Count Albumin NAFLD Fibrosis Score Explanation and Clinical Context NAFLD Fibrosis Score is a validated noninvasive tool used to estimate the likelihood of advanced liver fibrosis in individuals with nonalcoholic fatty liver disease. The score integrates routine clinical and laboratory variables including age body mass index impaired fasting
Nakata Index and McGoon Ratio: Explanation and Clinical Context Nakata Index and McGoon Ratio are quantitative assessments of pulmonary artery size often used when evaluating patients with congenital heart diseases that involve reduced pulmonary blood flow. Both indices help clinicians determine surgical suitability, especially for procedures such as systemic to pulmonary artery shunts, complete repair of Tetralogy o
Excessive high pitched cry None or normal High pitched but consolable Continuous high pitched and inconsolable Sleep after feeding (hours) More than 3 hours 2 to 3 hours 1 to 2 hours Less than 1 hour Moro reflex Normal Hyperactive Markedly hyperactive Tremors disturbed None Mild Moderate to severe Tremors undisturbed None Mild Marked Increased muscle tone Absent Present Excoriation Absent Present Myoclonic jerks Abse
National Amyloidosis Centre (NAC) Risk Score: Explanation and Clinical Context The NAC staging system stratifies patients with transthyretin cardiac amyloidosis (ATTR-CA) into prognostic categories based on NT-proBNP and eGFR levels. Stage 1 indicates a lower risk of mortality, while Stage 3 denotes a higher risk. This system aids clinicians in assessing disease severity and guiding treatment decisions.
: Explanation and Clinical Context This tool estimates the 5-year risk of sudden cardiac death based on patient characteristics collected in national SCD registries. It incorporates variables including age, sex, history of myocardial infarction, left ventricular ejection fraction (LVEF), and history of heart failure. The model uses logistic regression to calculate the probability of SCD. Higher predicted percentages
Native T1 Mapping Index (T1 Time): Comprehensive Explanation and Clinical Context Native myocardial T1 reflects the longitudinal relaxation of protons in tissue and rises with increased free water or extracellular matrix expansion (edema, diffuse fibrosis, amyloidosis) and falls with intracellular storage (Anderson–Fabry, iron overload). Absolute T1 values depend on magnetic field strength (1.5T vs 3T) and mapping se
Clinical reference for Natriuretic Peptide Creatinine Ratio Npcr Calculator, with practical context for use alongside current guidance and professional judgment.
Navy Method Body Fat Explanation and Clinical Context The Navy Method is an anthropometric formula used to estimate body fat percentage based on body circumference measurements. It requires height, waist circumference, and neck circumference for men, with additional hip circumference for women. This method was developed by the United States Navy as a practical field tool that does not require advanced equipment. Norm
NCDR-LAAO Mortality Score: Explanation and Clinical Context The National Cardiovascular Data Registry–Left Atrial Appendage Occlusion (NCDR-LAAO) Mortality Risk Model is a validated predictive tool designed to estimate the likelihood of in-hospital mortality following percutaneous left atrial appendage occlusion (LAAO) procedures. Developed from the comprehensive NCDR LAAO Registry in the United States, which include
Neck Disability Index Explanation and Clinical Context The Neck Disability Index is a widely used patient reported outcome measure for evaluating functional impairment related to neck pain. It assesses ten domains of daily activities which include pain intensity personal care lifting reading headaches concentration work driving sleeping and recreation. Each item provides six possible responses scored from zero to fiv
Neonatal Pulmonary Hypertension (NPH) Risk Index: Explanation and Clinical Context The Neonatal Pulmonary Hypertension Risk Index is a validated scoring system designed to stratify the risk of pulmonary hypertension in neonates, particularly preterm infants. It incorporates key clinical variables available shortly after birth, including gestational age, birth weight, need for mechanical ventilation, and oxygenation i
Neonatal Sepsis Score Explanation and Clinical Context Neonatal sepsis represents a systemic response to infection in the newborn period and remains a leading cause of morbidity and mortality in early life. The Neonatal Sepsis Score is intended to aid clinicians in recognizing early signs of infection by integrating simple bedside clinical indicators. Temperature instability reflects impaired thermoregulation caused
Net Reclassification Index (NRI): Explanation and Clinical Context The Net Reclassification Index (NRI) is a statistical metric used to quantify the improvement in risk prediction offered by a new model compared to an existing model. It evaluates whether individuals with events (cases) are more correctly reclassified into higher risk categories and whether individuals without events (non-cases) are correctly reclassi
Neutrophil–Lymphocyte Ratio (NLR): Explanation and Clinical Context The Neutrophil–Lymphocyte Ratio (NLR) is calculated by dividing the absolute neutrophil count by the absolute lymphocyte count. It is an inexpensive and widely available marker of systemic inflammation. Elevated NLR has been associated with adverse outcomes in cardiovascular diseases, cancer, and critical illness. Cut-offs vary by clinical context, b
NEWS Early Warning Score Explanation and Clinical Context The National Early Warning Score is a clinical scoring system designed to identify patients at risk of acute deterioration in hospital settings. The score integrates respiratory rate oxygen saturation the need for supplemental oxygen systolic blood pressure heart rate temperature and level of consciousness. Each variable contributes a weighted score based on s
Interpretation and clinical use The NEXUS C Spine Clearance Rule identifies five clinical criteria. If none of the five criteria are present in a patient who is clinically reliable, the likelihood of clinically important cervical spine injury is low and radiographic imaging may be avoided. If any criterion is present imaging is recommended. Clinical reliability includes normal mental status and absence of significant
NGAL Predictive Model: Explanation and Clinical Context The NGAL predictive model estimates the risk of acute kidney injury (AKI) based on serum NGAL levels, age, and serum creatinine. Elevated NGAL levels are indicative of kidney injury, and when combined with clinical parameters, they enhance the accuracy of AKI risk stratification.
NIH Stroke Scale (NIHSS): Explanation and Clinical Context The NIH Stroke Scale (NIHSS) is a standardized tool developed by the National Institutes of Health to objectively quantify the neurological deficit in acute stroke patients. It evaluates 11 domains of neurological function, including level of consciousness, gaze, vision, facial movement, motor strength, ataxia, sensation, speech, and neglect. The total score
Non-HDL-C to LDL-C Ratio: Explanation and Clinical Context The Non-HDL-C to LDL-C ratio represents the proportion of total atherogenic lipoproteins (all apoB-containing particles) relative to LDL cholesterol. While LDL-C has long been the cornerstone of lipid management, non-HDL-C provides a more comprehensive view of atherogenic burden, encompassing VLDL, IDL, and lipoprotein(a). Definition: Non-HDL-C is calculated
Inferior vena cava Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the ASE and EACVI (2015)
Left ventricle (Size) Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the ASE and EACVI (2015) Left ventricle (Mass) Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the ASE and EACVI (2015) Left ventricle (Volume) Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the ASE and
Aorta (Size) Echocardiography in aortic diseases: EAE recommendations for clinical practice (2010)
Left ventricular diastolic function LAP indeterminate if only 1 of 3 parameters available. Pulmonary vein S/D ratio <1 applicable to conclude elevated LAP in patients with depressed LV EF. Recommendations for the Evaluation of LV Diastolic Function by Echocardiography: An Update from the ASE and EACVI (2016)
Northern New England CABG Mortality Risk Model: Explanation and Clinical Context This model was developed to predict in-hospital mortality for patients undergoing isolated coronary artery bypass graft (CABG) surgery in the Northern New England region of the United States. The model utilizes preoperative clinical variables to estimate the risk of mortality, aiding clinicians in decision-making and patient counseling.
NOVA Score (Nosocomial vs Community IE): Explanation and Clinical Context The NOVA score is a validated tool designed to differentiate nosocomial infective endocarditis (IE) from community-acquired IE in hospitalized patients. It incorporates four clinical parameters: neutrophil count, organ failure, prosthetic valve presence, and acquisition setting (nosocomial vs community). Each parameter contributes to a total sc
Gupta (NSQIP) MICA Risk Calculator Estimate 30-day risk of perioperative myocardial infarction or cardiac arrest (MICA) using the ACS-NSQIP–derived Gupta model. Enter preoperative variables below and click Calculate. NSQIP (Gupta) MICA: Explanation, Clinical Context, and References this calculator uses the ACS NSQIP-derived Gupta model to estimate the probability of myocardial infarction or cardiac arrest withi
Explanation and Clinical Context This decision tool is designed for patients with non ST segment elevation acute coronary syndromes who are potential candidates for coronary revascularization. The tool combines the GRACE risk score with simple clinical variables to help clinicians decide between a routine invasive strategy and a selective invasive strategy, and to estimate the appropriate timing of coronary angiograp
Explanation and Clinical Context This tool is intended for adults who present with non ST elevation acute coronary syndrome and in whom type 1 myocardial infarction due to plaque rupture is suspected. It summarizes key predictors that are mentioned in the twenty twenty five acute coronary syndrome guideline to estimate the likely benefit from an early invasive strategy and to suggest a practical time window for coron
NSVT Duration Index: Explanation and Clinical Context The NSVT Duration Index quantifies the burden of nonsustained ventricular tachycardia (NSVT) over a defined monitoring period. It is calculated as the total duration of NSVT episodes divided by the total duration of monitoring (in minutes). This index provides a standardized measure to assess arrhythmic risk in patients with cardiomyopathies, ischemic heart diseas
NT-proBNP/BNP Ratio: Explanation and Clinical Context The NT-proBNP/BNP ratio is a prognostic biomarker used in heart failure and cardiovascular risk assessment. NT-proBNP, the inactive N-terminal fragment of proBNP, and BNP, the biologically active peptide, reflect ventricular wall stress and myocardial dysfunction. Differences in clearance mechanisms and half-lives may cause discrepancies in absolute concentrations
Control Event Rate CER Experimental Event Rate EER Number Needed to Treat NNT or Number Needed to Harm NNH Explanation and Clinical Context Number Needed to Treat is a measure that reflects how many patients need to receive a specific intervention for one additional patient to benefit compared with control therapy. When the treatment reduces adverse outcomes the absolute risk reduction becomes positive and the result
NYHA Class Change Index: Explanation and Clinical Context The NYHA Class Change Index quantifies the difference in New York Heart Association (NYHA) functional class before and after a rehabilitation program. It is calculated by subtracting the post-rehabilitation class from the pre-rehabilitation class. Positive values indicate functional improvement, negative values indicate worsening, and zero indicates no change.
NYHA Functional Class: Explanation and Clinical Context The NYHA (New York Heart Association) Functional Classification is a widely used system to assess the severity of heart failure symptoms and their impact on physical activity. It classifies patients into four categories: Class I (no limitation of physical activity), Class II (slight limitation), Class III (marked limitation), and Class IV (symptoms at rest). Thi
Clinical reference for NYHA ICD Benefit Index Calculator, with practical context for use alongside current guidance and professional judgment.
Clinical reference for NYHA Pregnancy Composite Risk Score Calculator, with practical context for use alongside current guidance and professional judgment.
OBSERVANT Score (TAVI): Explanation and Clinical Context The OBSERVANT Score is a validated tool developed to estimate 30-day mortality risk for patients undergoing Transcatheter Aortic Valve Replacement (TAVR). It utilizes simple clinical variables available at hospital admission, including glomerular filtration rate (eGFR), critical preoperative state, New York Heart Association (NYHA) functional class IV, pulmonar
OBSERVANT Score (TAVI): Explanation and Clinical Context The OBSERVANT Score is a validated tool developed to estimate 30-day mortality risk for patients undergoing Transcatheter Aortic Valve Replacement (TAVR). It utilizes simple clinical variables available at hospital admission, including glomerular filtration rate (eGFR), critical preoperative state, New York Heart Association (NYHA) functional class IV, pulmonar
: Explanation and Clinical Context This calculator estimates the incremental cardiovascular hazard associated with occupational fine particulate (PM2.5) exposure by converting a time-weighted PM2.5 increment (workplace minus ambient, adjusted for exposure hours and control efficiency) into a hazard ratio using meta-analytic coefficients (≈10% higher risk per 10 μg/m3 increase). The tool translates population-based ex
Occupational Noise – Cardiac Hypertension Index (ON-CHI): Explanation and Clinical Context The ON-CHI is a conceptual tool that estimates the incremental hypertensive risk attributable to occupational noise exposure through a simple “risk-points” model integrating ambient noise level (LAeq,8h in dB(A)) and cumulative exposure duration (years). Chronic exposure to elevated occupational noise triggers sympathetic nervo
Occupational Sedentary Behaviour Cardiac Risk Score: Explanation and Clinical Context This tool provides an approximate risk stratification for cardiovascular (cardiac) risk based on occupational sedentary behaviour, demographic and lifestyle variables. Prolonged occupational sitting has been identified as a potential modifiable risk exposure for cardiometabolic disease and cardiovascular outcomes: for instance, indi
Ontario CABG Risk Score: Explanation and Clinical Context The Ontario CABG Risk Score is a validated tool designed to estimate the risk of operative mortality in patients undergoing coronary artery bypass grafting surgery. It incorporates preoperative variables including age, sex, left ventricular ejection fraction (LVEF), history of myocardial infarction, urgency of surgery, chronic renal failure, chronic pulmonary
OPEN-CTO Mortality Model: Explanation and Clinical Context “OPEN-CTO” refers to the prospective multicenter Outcomes, Patient Health Status, and Efficiency in Chronic Total Occlusion (OPEN-CTO) registry, which has served as an external validation cohort for contemporary CTO PCI risk tools. The most widely cited periprocedural mortality model for CTO PCI derives from the PROGRESS-CTO registry and was externally valida
OPTIMIZE-HF Discharge Readmission Model: Explanation and Clinical Context OPTIMIZE-HF (the Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients with Heart Failure) was a large hospital registry and quality-improvement programme that prospectively collected 60–90 day post-discharge outcomes in a sample of enrolled patients. OPTIMIZE-HF analyses identified several clinical variables strongly asso
OPTIMIZE-HF Risk Score: Explanation and Clinical Context OPTIMIZE-HF (Organized Program to Initiate Lifesaving Treatment in Hospitalized Patients with Heart Failure) Score is a validated clinical tool developed to estimate in-hospital mortality risk for patients admitted with acute decompensated heart failure. It uses readily available clinical variables at hospital admission including age, systolic blood pressure, h