1,329 calculators and references across 60 specialties, with formula confidence shown up front.
T-wave Alternans (TWA): Explanation and Clinical Context T-wave Alternans (TWA) refers to beat-to-beat variations in the amplitude or morphology of the T-wave on the electrocardiogram, reflecting repolarization heterogeneity. Elevated microvolt-level TWA has been validated as a non-invasive marker for increased risk of ventricular arrhythmias and sudden cardiac death, particularly in patients with structural heart di
T1/T2 Mapping Index: Explanation and Clinical Context The T1/T2 Mapping Index is derived from cardiac MRI T1 and T2 relaxation times, providing a quantitative assessment of myocardial tissue characteristics. T1 mapping reflects interstitial fibrosis, edema, or infiltration, while T2 mapping is sensitive to myocardial edema. The index (T1/T2 ratio) allows clinicians to detect early myocardial abnormalities and differe
T1/T2 Mapping Ratio in Myocarditis: Explanation and Clinical Context T1/T2 mapping ratio is a non-invasive CMR-based metric used to quantify myocardial tissue changes in suspected myocarditis. T1 relaxation time reflects myocardial fibrosis and edema, while T2 relaxation time predominantly reflects myocardial water content and inflammation. The ratio of T1/T2 helps to stratify the likelihood of active myocardial infl
Inputs (all numeric, use dot for decimals) T2 Mapping Edema Index: Explanation and Clinical Context T2 mapping quantifies myocardial transverse relaxation time (T2) in milliseconds on a pixel-wise basis. Elevated myocardial T2 reflects increased free water and serves as a quantitative index of myocardial edema. About the parameters: • T2 (ms): quantitative value representing water content in myocardium. • Z-score: de
Explanation and Clinical Context The GRACE risk model is widely used for early mortality and adverse event risk estimation in non ST elevation ACS and is endorsed within the AHA ACS Guideline 2025 as a validated tool for guiding treatment intensity including invasive strategy timing pharmacotherapy duration and monitoring needs. Variables in this calculator represent core elements of GRACE which include age heart rat
Table Based TIMI NSTEMI STEMI Tool Explanation and Clinical Context This tool is based on the TIMI risk model integrated in the twenty twenty five acute coronary syndrome guideline as one of validated approaches for rapid prognosis stratification in unstable angina and NSTEMI STEMI continuum. It assigns one point to seven clinical variables including older age sixty five or more, presence of three or more traditional
Takotsubo (InterTAK) Prognostic Score: Explanation and Clinical Context The InterTAK Prognostic Score is a validated tool derived from the International Takotsubo Registry to estimate the risk of in-hospital complications and adverse events in patients with Takotsubo syndrome. It incorporates clinical and demographic variables including gender, emotional and physical triggers, ST-segment elevation, QTc prolongation,
Explanation — TAPSE, physiology, clinical meaning, and prognostic context TAPSE (tricuspid annular plane systolic excursion) quantifies the longitudinal displacement of the lateral tricuspid annulus toward the apex during systole and therefore serves as a simple surrogate of right ventricular longitudinal systolic function. It is measured in M-mode aligned with the lateral tricuspid annulus in the apical four-chamber
TAPSE/PASP Optimization Index: Comprehensive Explanation and Clinical Context Definition & Formula: The TAPSE/PASP ratio (mm/mmHg) is a noninvasive surrogate of right ventricular-pulmonary arterial (RV-PA) coupling. It is calculated as tricuspid annular plane systolic excursion (TAPSE, in mm) divided by pulmonary artery systolic pressure (PASP, in mmHg). Measurement: TAPSE is measured by M-mode at the lateral tricusp
TAPSE/PASP Ratio: Explanation and Clinical Context The TAPSE/PASP ratio is a non-invasive echocardiographic index used to assess the coupling between right ventricular (RV) function and pulmonary arterial load. TAPSE (Tricuspid Annular Plane Systolic Excursion) measures longitudinal RV systolic function, while PASP (Pulmonary Artery Systolic Pressure) reflects the afterload imposed on the RV. This ratio provides insi
TAPVR Repair Risk Index: Explanation and Clinical Context Total Anomalous Pulmonary Venous Return (TAPVR) is a rare congenital heart defect where pulmonary veins drain abnormally into the right atrium or systemic veins, leading to cyanosis and increased pulmonary blood flow. Surgical repair is essential, but postoperative complications, including reinterventions, remain a concern. The TAPVR Repair Risk Index is a cli
Target Cardiac Output (CO): Explanation and Clinical Context Target cardiac output represents the estimated cardiac output required to maintain adequate systemic perfusion in relation to an individual's body surface area. The formula uses a standard cardiac index value of 2.2 liters per minute per square meter, which reflects the minimal cardiac index associated with preserved organ perfusion in hemodynamically stabl
FRANCE-2 TAVI Risk Score (Precise Logistic Model): Explanation and Clinical Context The FRANCE-2 TAVI Risk Score uses a logistic regression model to predict 30-day mortality after transcatheter aortic valve implantation (TAVI) in patients with severe aortic stenosis. Predictors include age, NYHA class IV, peripheral artery disease, atrial fibrillation, serum creatinine, left ventricular ejection fraction (LVEF), and
TAVR Mortality Score (TVT Registry): Explanation and Clinical Context The TAVR Mortality Score developed by the TVT Registry is a validated predictive tool for estimating 30-day mortality after transcatheter aortic valve replacement (TAVR). It uses key clinical variables available prior to the procedure, including age, sex, NYHA class IV, serum creatinine, left ventricular ejection fraction (LVEF), history of prior C
TAVR Valve Academic Research Consortium (VARC-3) Classification: Explanation and Clinical Context VARC-3 provides a standardized framework to assess patient risk, procedural outcomes, and complications after transcatheter aortic valve replacement (TAVR). This classification incorporates clinical, anatomical, and procedural variables, such as age, surgical risk scores (e.g., STS-PROM), functional status (NYHA class),
TB Pericarditis Complication Risk Model: Explanation and Clinical Context This calculator estimates a relative hazard index (RHI) for two major complications of tuberculous pericarditis—death and constrictive pericarditis—based on multivariable predictors from the IMPI program. In HIV-infected patients, higher NYHA class, hypotension, peripheral oedema, and lower weight increased mortality hazard. For constrictive pe
TB Pericarditis Non Cardiac Risk Score Explanation and Clinical Context This clinical scoring system is designed to support the identification of tuberculous pericarditis in patients who present with pericardial effusion without dominant cardiac causes. The score uses simple non cardiac clinical indicators that reflect systemic inflammatory and infectious processes including fever night sweat weight loss prolonged co
Head and Neck Percentage Anterior Trunk Percentage Posterior Trunk Percentage Right Arm Percentage Left Arm Percentage Right Leg Percentage Left Leg Percentage Perineum Percentage Explanation and Clinical Context Total Body Surface Area or TBSA estimation is a foundational step in the initial management of burn patients. Accurate assessment helps determine fluid resuscitation needs, predicts systemic impact, and guid
: Explanation and Clinical Context The Telemonitoring Cost-Benefit Cardiac Program Model is designed to estimate the financial impact and efficiency of implementing telemonitoring programs for patients with chronic heart failure or post–cardiac hospitalization follow-up. It combines key cost elements — baseline hospitalization cost, expected reduction in readmissions, and telemonitoring program expenses — to produce
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Triglyceride/HDL-C Ratio: Explanation and Clinical Context The triglyceride to high-density lipoprotein cholesterol (TG/HDL-C) ratio is a widely studied marker reflecting atherogenic dyslipidemia and insulin resistance. A higher ratio is associated with increased cardiovascular risk, metabolic syndrome, and subclinical atherosclerosis. Typical thresholds categorize risk as follows: <2 = low risk, 2–4 = intermediate r
TG/HDL-C Ratio: Explanation and Clinical Context The triglyceride to HDL-cholesterol (TG/HDL-C) ratio is a simple, reliable marker used to estimate insulin resistance and cardiometabolic risk. It is calculated by dividing fasting triglycerides (mg/dL) by HDL-C (mg/dL). A low ratio (<2) generally indicates low risk for insulin resistance and cardiovascular events, while a high ratio (>4) suggests significant insulin r
: Explanation and Clinical Context This tool estimates the probability of an adverse surgical outcome (e.g., mortality or major complication) after repair of transposition of the great arteries, based on key preoperative and intraoperative variables (age at surgery, ventricular function, presence of a VSD, complexity of coronary anatomy, ischemic time). In this sample implementation, a logistic regression model is as
Pericardial effusion Recommendations for Cardiac Chamber Quantification by Echocardiography in Adults: An Update from the ASE and EACVI (2015)
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: Explanation and Clinical Context The Thyroid Dysfunction Cardiovascular Risk Index is a predictive model designed to quantify cardiovascular risk associated with abnormal thyroid function using continuous TSH levels. It incorporates TSH levels, age, sex, systolic blood pressure, and total cholesterol to calculate a continuous risk index. Higher TSH levels, advanced age, male sex, elevated systolic blood pressure, a
TSH (mIU per L) Free T4 (ng per dL) Thyroid Function Index Panel Explanation and Clinical Context The Thyroid Function Index is an integrated measure that combines serum TSH and free T4 to provide a more stable and physiologically relevant indicator of thyroid status. TSH alone can fluctuate because of pituitary dynamics and non thyroidal influences while free T4 may remain within reference intervals in early thyroid
Explanation and Clinical Context This clinical tool assists in bedside decision making for long term P2Y12 therapy in patients treated for acute coronary syndrome with percutaneous coronary intervention. The twenty twenty five acute coronary syndrome guideline describes that ticagrelor based dual antiplatelet therapy for up to twelve months is the standard after PCI unless bleeding risk becomes unacceptable. Recurren
References American Heart Association Twenty twenty five Guideline for Management of Acute Coronary Syndromes JACC Twenty twenty five Mehran R et al Ticagrelor with or without aspirin after PCI NEJM Twenty nineteen Kim B K et al Ticagrelor monotherapy versus ticagrelor plus aspirin in ACS after PCI TICO trial JACC Twenty twenty
Explanation - TIMI Risk Score for STEMI: Comprehensive Overview The TIMI Risk Score for STEMI (Thrombolysis In Myocardial Infarction) is a clinical tool used to estimate short-term (30-day) mortality in patients with ST-elevation myocardial infarction. It was developed by Morrow et al. (Circulation, 2000) using data from the InTIME-II trial, aiming to simplify bedside risk assessment at patient presentation. Each cli
TIMI Risk Score for UA/NSTEMI: Comprehensive Explanation and Clinical Context The TIMI (Thrombolysis In Myocardial Infarction) Risk Score is a validated tool used to predict the likelihood of adverse cardiovascular outcomes (death, myocardial infarction, or urgent revascularization) within 14 days in patients with Unstable Angina (UA) or Non ST-Elevation Myocardial Infarction (NSTEMI). It consists of seven clinical p
Tobacco/Drug Use Cardiac Athlete Risk Multiplier: Explanation and Clinical Context This tool provides an approximate multiplier of cardiovascular risk among athletes with a history of tobacco or recreational drug use. The calculation integrates age-related risk, resting heart rate, cumulative exposure (in years), and the physiological impact of the specific substance used. Chronic nicotine exposure increases sympathe
TOF Risk Stratification Index (RVOT Gradient + Anatomy): Explanation and Clinical Context The TOF Risk Stratification Index estimates post-operative risk in patients with Tetralogy of Fallot (TOF) based on right ventricular outflow tract (RVOT) gradient and anatomical complexity. RVOT gradient reflects the severity of right ventricular obstruction, while anatomical complexity accounts for coronary artery anomalies, p
Total Energy Expenditure TDEE Explanation and Clinical Context Total Energy Expenditure represents the total amount of energy that the human body uses in a full day. It reflects basal metabolic processes physical activity and the thermic effect of food. Basal Metabolic Rate is the energy required to maintain essential physiological processes at rest and it forms the largest portion of TDEE. Physical activity modifies
Tpeak-Tend Interval Index: Explanation and Clinical Context The Tpeak-Tend (Tpe) interval represents the time from the peak to the end of the T wave on the ECG and reflects transmural dispersion of repolarization. The Tpe Index, calculated as Tpe/QT ratio, normalizes the Tpe interval relative to the QT interval and provides a dimensionless measure of ventricular repolarization heterogeneity. Increased Tpe Index has b
TRACE Study — Post-MI Heart Failure Risk (explanation and clinical context) This calculator is TRACE-inspired: the original TRAndolapril Cardiac Evaluation (TRACE) was a randomized trial that enrolled patients with reduced left ventricular function soon after myocardial infarction and demonstrated morbidity and mortality benefits of long-term ACE inhibition (trandolapril) in that population. TRACE showed that LV syst
: Explanation and Clinical Context The TRANSFORM-HF Mortality Comparison Index is derived from the TRANSFORM-HF trial (Felker GM, et al., NEJM 2022), which compared torsemide and furosemide in patients hospitalized with heart failure. The trial demonstrated no statistically significant difference in all-cause mortality at 12 months between the two diuretics (26.1% vs 26.2%; HR 1.02, 95% CI 0.89–1.18). This calculator
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Transseptal Puncture Complexity Index (Experimental): Comprehensive Explanation and Clinical Context This calculator proposes a pragmatic, literature-informed composite score to anticipate technical complexity of transseptal puncture (TSP) before left atrial procedures. Factors that repeatedly correlate with difficult access include prior TSP or septal instrumentation (e.g., occluder/patch), challenging thoracic or c
Urine Potassium Plasma Potassium Urine Osmolality Plasma Osmolality Transtubular Potassium Gradient TTKG Explanation and Clinical Context TTKG is a physiologic estimate of potassium secretion in the cortical collecting duct and reflects the activity of aldosterone as well as distal tubular sodium delivery. It is calculated by the ratio of urine potassium concentration to plasma potassium concentration multiplied by t
Travel Region (primary) Country (optional) Days Since Return Length of Stay (days) Key Exposures (check all that apply) Freshwater swimming/canyoning Heavy mosquito exposure Tick exposure Unpasteurized dairy / farm animal contact Rural/adobe housing (triatomine exposure) Clinical Features (check all that apply) Fever Chest pain Dyspnea Palpitations/syncope New murmur/heart failure signs Eosinophilia Key Tests/History
TRED-HF Recovery / Relapse Prediction — explanation and clinical context The TRED-HF randomized pilot trial examined phased withdrawal of all heart failure pharmacotherapy in carefully selected patients with previously dilated cardiomyopathy who had asymptomatic recovery of left ventricular function (LVEF ≥50%), normalised indexed LV volumes, and low NT-proBNP at baseline; approximately 40–44% of participants relapse
: Explanation and Clinical Context The GLIDE score is an anatomy-based predictor to estimate procedural success following tricuspid transcatheter edge-to-edge repair (T-TEER), including TriClip. It integrates five echocardiographic variables: septolateral coaptation gap (0–5 mm vs. ≥6 mm), TR jet location (anteroseptal/central vs. posteroseptal/anteroposterior/diffuse), TEE image quality (good vs. limited), chordal d
: Explanation and Clinical Context This calculator classifies tricuspid regurgitation (TR) severity according to the 5-grade scheme used in the TRILUMINATE program (trace/mild, moderate, severe, massive, torrential). It integrates quantitative echocardiographic parameters — vena contracta (VC), effective regurgitant orifice area (EROA), regurgitant volume (RVol), and 3D vena contracta area (VCA) — using evidence-base
TRISS Trauma Injury Severity Score Explanation and Clinical Context TRISS is a validated method for estimating the probability of survival in trauma patients by integrating three established components of trauma assessment which are the Revised Trauma Score the Injury Severity Score and patient age. The model also incorporates the mechanism of trauma which is categorized as blunt or penetrating because outcomes diffe
Tropical Myocarditis Severity Index (TMSI): Explanation and Clinical Context The Tropical Myocarditis Severity Index (TMSI) is a pragmatic bedside score tailored for use in tropical, resource-limited healthcare settings where myocarditis frequently presents secondary to infections such as dengue, rickettsioses, Chagas disease, and leptospirosis. The index prioritizes clinically accessible variables—hemodynamics, arrh
Troponin–CK-MB Concordance Index: Explanation and Clinical Context The Troponin–CK-MB Concordance Index is a predictive tool designed to assess the agreement between troponin and CK-MB levels in detecting myocardial injury. It is calculated as the ratio of troponin to the sum of troponin and CK-MB, reflecting how much troponin predominates relative to CK-MB. Higher values indicate a stronger concordance of troponin w
TRUE-AHF Prognostic Classification — explanation and clinical context This page implements an experimental prognostic classifier inspired by common predictors used in acute heart failure (AHF) prognostic models: advanced age, low systolic blood pressure, tachycardia, elevated BUN/creatinine, hyponatremia, elevated natriuretic peptides (NT-proBNP), reduced left ventricular ejection fraction, and positive cardiac tropo
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: Rationale, Interpretation & Clinical Context Truncating variants in the TTN gene (TTNtv) are among the most common genetic contributors to dilated cardiomyopathy (DCM) and have been associated with increased risk of heart failure, atrial fibrillation, and adverse cardiac events in multiple cohort studies. Risk modifiers identified across the literature include whether the TTNtv lies in exons with high proportion sp
TVT Registry Mortality Score: Explanation and Clinical Context The TVT Registry Mortality Score is a validated tool developed by the Society of Thoracic Surgeons and the American College of Cardiology to estimate in-hospital mortality risk for patients undergoing transcatheter aortic valve replacement (TAVR). It incorporates patient demographics, comorbidities, heart failure severity, renal function, procedural acces
Exploratory : Explanation and context The TWILIGHT randomized trial tested whether, among high-risk patients who had completed 3 months of dual antiplatelet therapy after PCI, stopping aspirin and continuing ticagrelor monotherapy reduced clinically relevant bleeding without increasing ischemic events. The trial found a lower rate of BARC 2/3/5 bleeding with ticagrelor monotherapy versus ticagrelor plus aspirin, with
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Age BMI Waist Circumference in cm Physical Activity less than thirty minutes per day No Yes Family History of Diabetes in first degree relative No Yes History of Hypertension No Yes Type 2 Diabetes Risk Score Explanation and Clinical Context This tool estimates the risk of developing type 2 diabetes using simple clinical variables including age, body mass index, waist circumference, physical activity, family history