Cardiac arrest is the sudden cessation of coordinated mechanical cardiac function — abruptly stopping circulation and oxygen delivery to the brain, heart, and vital organs — producing clinical death within minutes if untreated. It is critically distinguished from myocardial infarction (which is a blockage event that may or may not cause arrest) and heart failure (a chronic pump dysfunction that reduces output but does not stop the heart): cardiac arrest is the electrical and mechanical emergency that ends all circulation, producing immediate unconsciousness, apnea, and pulselessness. The four underlying electrical mechanisms define both the arrest type and the treatment algorithm: ventricular fibrillation (VF) and pulseless ventricular tachycardia (pVT) are shockable rhythms — immediately treated with electrical defibrillation alongside CPR, with epinephrine and amiodarone/lidocaine in subsequent ACLS cycles; pulseless electrical activity (PEA) and asystole are non-shockable rhythms — treated exclusively with high-quality CPR and epinephrine while reversible causes (the “H’s and T’s”: Hypovolemia, Hypoxia, Hydrogen ion [acidosis], Hypo/hyperkalemia, Hypothermia; Tension pneumothorax, Tamponade, Toxins, Thrombosis [PE], Thrombosis [MI]) are identified and corrected. Return of spontaneous circulation (ROSC) is the immediate survival milestone, followed by post-cardiac arrest syndrome management including targeted temperature management (TTM), hemodynamic optimization, and coronary angiography when indicated. The 2025 AHA ACLS Guidelines reaffirm early defibrillation for shockable rhythms and high-quality CPR (rate 100-120/min, depth ≥2 inches) as the two interventions with the strongest evidence for survival.
Clinical Indicators: ICD-10-CM encodes cardiac arrest under category I46, but I46 itself is NON-BILLABLE — all three billable codes (I46.2, I46.8, I46.9) carry critical “Code first” sequencing instructions for I46.2 and I46.8 requiring the underlying cause to be sequenced as the principal diagnosis. Only I46.9 (cause unspecified) may serve as principal diagnosis. The former I46.0 (cardiac arrest due to VF) was deleted from ICD-10-CM — VF as the cause of cardiac arrest is no longer a distinct code; use I46.2 with the underlying cardiac condition (VF coded separately as I49.01) when documented.
“Heart; stomach” — the primary Greek root for the heart; notably, kardia also denoted the upper stomach (cardia of the stomach) in antiquity, which is why some gastric terms (e.g., cardia, cardioesophageal) also carry this root; became Latin cardiacus and English cardiac ~1600; appears in cardiac, cardiology, cardiomyopathy, pericardium, bradycardia, tachycardia
”Of, pertaining to, relating to” — adjectival suffix converting a noun into an adjective; cardiacus (“pertaining to the heart”) entered English through French cardiaque (14th century) before direct Latin borrowing; appears in cardiac, maniac, celiac, thoracic
arrest
Old French arester → Latin ad- + restare
”To stop, to stand still; to cause to stop” — from Latin ad- (“to, at”) + restare (“to remain, to stop”); the clinical sense of “sudden cessation/stopping” of a physiological process is attested in English medical literature from the 17th century; the compound “cardiac arrest” as a formal medical term is attested from 1950 per the Oxford English Dictionary and etymonline
Literally: “A stopping pertaining to the heart” — a surprisingly recent clinical compound, formally coined in 1950 as cardiac resuscitation science began to mature. The term elegantly captures the pathophysiological event: the heart (kardia) has been stopped (arrested) — making it one of the most literally accurate compound terms in all of emergency medicine. The Greek root kardia traces back to the Proto-Indo-European root *kerd- (“heart”), the same ancestor that gives Latin cor/cordis (“heart”), Old English heorte, and modern English heart — a root shared across the entire Indo-European language family. The clinical compound “cardiac arrest” entered standardized medical usage in the same era as CPR (formally described in the 1960 JAMA paper by Kouwenhoven, Jude, and Knickerbocker), fundamentally reshaping emergency medicine.
🔀 ALIASES / ALTERNATE TERMS
Term
Context
Sudden cardiac arrest (SCA)
The most common clinical synonym; specifically implies an unexpected event in a previously stable or ambulatory patient; I46.9 / I46.2 / I46.8 depending on documented etiology; commonly used in out-of-hospital arrest documentation.
Cardiopulmonary arrest
The compound term emphasizing simultaneous cessation of cardiac AND respiratory function; codes to the same I46.x family — there is no separate “cardiopulmonary arrest” code in ICD-10-CM.
Ventricular fibrillation arrest
Cardiac arrest with VF as the underlying mechanism; formerly I46.0 (now DELETED); code I46.2 (cardiac arrest due to underlying cardiac condition) + I49.01 (VF) when VF is the documented precipitating arrhythmia.
PEA (Pulseless Electrical Activity)
A non-shockable arrest rhythm with organized electrical activity but no mechanical output; no specific ICD-10-CM code — codes to the I46.x family based on underlying cause; the H’s and T’s search defines the underlying diagnosis that leads.
Asystole
Flat-line arrest — complete absence of electrical and mechanical activity; no specific ICD-10-CM code separate from the I46.x family; severity supported in documentation.
ROSC (Return of Spontaneous Circulation)
The immediate resuscitation milestone — when effective cardiac mechanical function is restored; NOT a separate ICD-10-CM code; its presence or absence influences post-arrest diagnosis selection (e.g., anoxic encephalopathy if ROSC is achieved but neurological damage occurred).
🔗 RELATED TERMS
Ventricular fibrillation — I49.01; the most common shockable arrest rhythm in adult out-of-hospital cardiac arrest; when VF causes cardiac arrest, code the underlying cardiac condition first (e.g., I25.10 for chronic ischemic heart disease), then I46.2, then I49.01 per the “Code first” instruction.
Ventricular tachycardia (pVT) — I47.2; pulseless ventricular tachycardia is a shockable rhythm treated identically to VF; code as an additional diagnosis when documented as the arrest mechanism.
Anoxic brain injury / Hypoxic-ischemic encephalopathy — G93.1; the most clinically significant post-ROSC complication — brain injury from the ischemic interval during arrest; code additionally when physician documents anoxic encephalopathy, hypoxic brain injury, or post-cardiac arrest brain injury.
Cardiogenic shock — R57.0; explicitly Excludes2 from I46 — both codes may be reported together when cardiac arrest is followed by or accompanied by cardiogenic shock; cardiogenic shock is NOT included in the cardiac arrest code.
Acute myocardial infarction — I21.3 (STEMI of unspecified site) / I21.9 (AMI unspecified) / STEMI-specific codes; the most common underlying precipitant of cardiac arrest; when AMI causes cardiac arrest, AMI sequences first (Code first instruction under I46.2) followed by I46.2.
Targeted temperature management (TTM) / Therapeutic hypothermia — No specific ICD-10-CM procedure code; inpatient reported via ICD-10-PCS 6A4Z0ZZ (hypothermia); CPT 99291/99292 (critical care) covers the physician management time for TTM post-ROSC.
Sudden cardiac death — I46.1; sudden cardiac death — heart stopped but did NOT respond to resuscitation (patient did not achieve ROSC); distinguished from cardiac arrest (I46.2/I46.8/I46.9) where resuscitation was attempted and ROSC was achieved or is ongoing; I46.1 is the appropriate code only when the patient died and there was no ROSC.
Acute respiratory failure — J96.00 / J96.01; frequently accompanies or precedes cardiac arrest; when documented as a co-existing condition post-ROSC, code separately.
CODING CORNER
🏥 ICD-10-CM CODES
Cardiac Arrest — Category I46
⚠️ ICD-10-CM / Chapter Nuances: I46 (parent) is NON-BILLABLE. The three billable codes carry critical sequencing instructions. I46.2 and I46.8 both carry a mandatory “Code first” instruction — the underlying cardiac condition (I46.2) or non-cardiac underlying condition (I46.8) must be sequenced as the principal/first-listed diagnosis, with the cardiac arrest code following. Only I46.9 (cause unspecified) may serve as the principal diagnosis when the etiology is undetermined. The former I46.0 (cardiac arrest due to ventricular fibrillation) was deleted from ICD-10-CM — do NOT use I46.0; VF-driven cardiac arrest uses I46.2 + I49.01 (VF). The Excludes2 note for cardiogenic shock (R57.0) means both I46.x and R57.0 may be reported together when both are documented.
Code
Description
I46.2
Cardiac arrest due to underlying cardiac condition (Code SECOND — the underlying cardiac condition goes first per “Code first” instruction; use when a cardiac etiology [ACS, VF, VT, cardiomyopathy, coronary artery disease] is the documented precipitant of the arrest)
I46.8
Cardiac arrest due to other underlying condition (Code SECOND — the non-cardiac underlying condition [e.g., sepsis, hypoxia, pulmonary embolism, drug toxicity, hypokalemia] goes first per “Code first” instruction; use when a non-cardiac etiology is the documented precipitant)
I46.9
Cardiac arrest, cause unspecified (The only I46.x code that may serve as principal/first-listed diagnosis; use when the etiology is not documented or cannot be determined despite workup — the most common code in the ED setting when cause is uncertain)
I46.1
Sudden cardiac death, so described (Use ONLY when the patient did NOT achieve ROSC and died — heart stopped and could not be resuscitated; do NOT use for patients who achieved ROSC and survived even briefly; completely distinct from I46.2/I46.8/I46.9 which apply to arrest with resuscitation attempt)
Ventricular fibrillation (Code additionally when VF is the documented arrest mechanism — previously I46.0 [now deleted]; pair with I46.2 when a cardiac condition [e.g., ACS, cardiomyopathy] drove the VF)
I47.2
Ventricular tachycardia (Code additionally when pulseless ventricular tachycardia [pVT] is documented as the arrest rhythm; also a shockable rhythm — treated identically to VF in ACLS)
I49.02
Ventricular flutter (Code additionally when ventricular flutter is the documented arrest mechanism)
Post-ROSC Complications (Code Additionally When Documented)
Anoxic brain damage, not elsewhere classified (The critical post-cardiac arrest code — hypoxic-ischemic encephalopathy (HIE) from the ischemic interval; code additionally when the physician explicitly documents anoxic or hypoxic brain injury, post-cardiac arrest encephalopathy, or HIE; dramatically elevates DRG severity weight)
R57.0
Cardiogenic shock (Excludes2 from I46 — may be coded additionally; use when cardiogenic shock is documented as a separate co-occurring condition post-ROSC)
J96.00
Acute respiratory failure, unspecified (Code additionally when acute respiratory failure is documented as a post-arrest complication — commonly present after prolonged arrest or in the post-ROSC phase requiring mechanical ventilation)
Acute kidney injury, unspecified (Post-arrest AKI from ischemia-reperfusion injury; code additionally when physician documents AKI in the post-resuscitation period)
E87.20
Metabolic acidosis, unspecified (Post-arrest lactic acidosis is near-universal; code additionally when physician documents metabolic acidosis or lactic acidosis as an active condition in the post-arrest workup)
Underlying Precipitating Cause (Sequences FIRST When Using I46.2 or I46.8)
Code
Description
I21.9
Acute myocardial infarction, unspecified (Sequences FIRST before I46.2 when AMI is the documented precipitant of cardiac arrest — the most common pairing in adult in-hospital and out-of-hospital cardiac arrest)
I25.10
Atherosclerotic heart disease of native coronary artery without angina pectoris (Sequences FIRST before I46.2 when chronic ischemic heart disease is the underlying cardiac condition)
I42.9
Cardiomyopathy, unspecified (Sequences FIRST before I46.2 when cardiomyopathy is the documented underlying cardiac cause)
Sepsis, unspecified organism (Sequences FIRST before I46.8 when sepsis is the documented non-cardiac precipitant — a common cause of PEA arrest)
J93.11
Primary spontaneous pneumothorax (Sequences FIRST before I46.8 when tension pneumothorax is the documented precipitant — a reversible “T” in the H’s and T’s algorithm)
I26.09
Other pulmonary embolism without acute cor pulmonale (Sequences FIRST before I46.8 when massive PE is the documented precipitant of PEA cardiac arrest)
🔧 COMMON CPT CODES (Emergency Resuscitation & Critical Care)
Resuscitation Procedures
⚠️ Critical CPT Nuance: 92950 (CPR) and critical care codes 99291/99292 are reportable on the same date of service, but the time spent performing CPR must be excluded from the critical care time calculation — CPR time cannot be double-counted as critical care time. 92950 includes chest compressions, ventilation, and emergency cardiac defibrillation when performed as part of CPR — do NOT separately report 92960 (external cardioversion/defibrillation) if it was performed as a component of the CPR resuscitation effort; 92960 is reserved for elective cardioversion of a rhythm in a patient who is NOT in cardiac arrest.
CPT Code
Description
92950
Cardiopulmonary resuscitation (e.g., in cardiac arrest) (The definitive CPR code — includes chest compressions, ventilation [bag-valve-mask], and emergency cardiac defibrillation when performed as part of the CPR event; report ONCE per resuscitation event; the time spent performing CPR must be excluded from concurrent critical care time calculation when 99291 is also billed)
Intubation, endotracheal, emergency procedure (Emergency endotracheal intubation for airway management during cardiac arrest; separately reportable from CPR; report ONCE regardless of number of intubation attempts; time spent performing intubation excluded from critical care time)
92960
Cardioversion, elective, electrical conversion of arrhythmia; external (Elective synchronized cardioversion — report ONLY for scheduled conversion of a stable arrhythmia in a patient NOT in cardiac arrest; do NOT report alongside 92950 for the same episode — defibrillation within CPR is included in 92950; cannot be reported within a critical care time block)
Critical Care — Post-Resuscitation Management
⚠️ Critical CPT Nuance: Critical care codes 99291 and 99292 are time-based. Minimum threshold for 99291 is 30 minutes of critical care time; below 30 minutes, use the appropriate E/M level. Critical care time must be personally spent by the billing physician in direct patient management — bedside, unit, or immediately available with direct patient involvement. Time documenting in the chart, reviewing results, and discussing with the care team counts if immediately related to the critical patient. 99291 is reported ONCE per patient per day; 99292 is added for each additional 30-minute block beyond the first 74 minutes. CPR time (92950), intubation time (31500), and other separately billable procedures must be subtracted from total critical care time before applying the time thresholds.
Critical care, evaluation and management of the critically ill or critically injured patient; first 30-74 minutes (Report ONCE per physician per patient per date for the first 30-74 minutes of critical care; includes post-ROSC management, hemodynamic stabilization, vasopressor titration, targeted temperature management oversight, and continuous monitoring; CPR time must be subtracted from this total)
+Critical care, each additional 30 minutes (Add-on; report for each additional 30-minute block of critical care time beyond the first 74 minutes; e.g., 75-104 min = 99291 + 99292 ×1; 105-134 min = 99291 + 99292 ×2; never alone)
Vascular Access — Cardiac Arrest
CPT Code
Description
36555
Insertion of non-tunneled centrally inserted central venous catheter; younger than 5 years of age (Pediatric central line insertion during cardiac arrest resuscitation)
36556
Insertion of non-tunneled centrally inserted central venous catheter; age 5 years and older (Adult/older pediatric central venous catheter insertion for vasoactive drug administration during or post-arrest resuscitation; separately reportable from critical care)
36600
Arterial puncture, withdrawal of blood for diagnosis (Arterial blood draw for post-ROSC ABG to assess pH, oxygenation, and lactate; if arterial line is placed, use 36620 instead)
36620
Arterial catheterization or cannulation for sampling, monitoring, or transfusion (separate procedure); percutaneous (Arterial line placement for continuous hemodynamic monitoring in post-cardiac arrest ICU management; separately reportable from critical care)
Post-Arrest Diagnostics
CPT Code
Description
93000
Electrocardiogram, routine ECG with at least 12 leads; with interpretation and report (Post-ROSC 12-lead ECG for STEMI/ischemia evaluation — critical in post-arrest protocol per 2025 AHA guidelines; separately reportable from critical care)
71046
Radiologic examination, chest; 2 views (Post-intubation, post-ROSC portable chest X-ray for ETT position confirmation and pulmonary assessment; separately reportable from critical care)
82803
Gases, blood, any combination of pH, pCO₂, pO₂, CO₂, HCO₃ (including calculated O₂ saturation) (Arterial blood gas — serial monitoring post-ROSC for acid-base status, oxygenation targets [avoid hyperoxia per 2025 guidelines], and ventilator management; append -91 for each repeat same-day ABG)
83605
Lactate (lactic acid) (Serial lactate monitoring post-arrest — lactic acidosis from ischemia is universal; lactate clearance tracks resuscitation adequacy; separately reportable from BMP/CMP)
Catheter placement in coronary artery(s) for coronary angiography, including intraprocedural injection(s) for coronary angiography, imaging supervision and interpretation; with right heart catheterization(Used for post-ROSC coronary angiography per 2025 AHA guidelines in suspected ACS-driven arrest — verify modifier application and bundling rules with PCI add-ons when PCI is performed)
93458
Catheter placement in coronary artery(s) for coronary angiography… left heart catheterization including intraprocedural injection(s) for left ventriculography, when performed (Left heart catheterization with coronary angiography; separately reported when ventriculography is also performed at the same session)
Significant, separately identifiable E/M service — Append to 99291 when CPR (92950) is performed on the same day; the E/M (critical care) is separately identifiable from the CPR procedure
Distinct procedural service — Append to separately reportable procedures (e.g., 36556 central line) performed during a critical care encounter to prevent NCCI bundling with the critical care codes
Professional component — Append to imaging codes (e.g., 71046 chest X-ray) when the physician provides only the interpretation and report, not the technical performance
Reduced services — Append to 92950 in the rare scenario where CPR was initiated but abbreviated (e.g., patient had a DNR identified mid-resuscitation and CPR was stopped); requires documentation supporting the reduced service
⚠️ Coding Note: The most critical compliance rules in cardiac arrest coding span sequencing, code deletion awareness, and CPR/critical care time separation. On sequencing: I46.2 and I46.8 are NEVER the principal diagnosis — the “Code first” mandatory instruction means the underlying cardiac or non-cardiac cause must always lead; placing I46.2 as the first-listed diagnosis when an underlying cause is documented is a sequencing error with DRG and reimbursement implications. On code deletion: I46.0 (cardiac arrest due to VF) was deleted from ICD-10-CM — submitting I46.0 generates an unrecognized code rejection; the correct coding for VF-driven arrest is I46.2 (Code first: the cardiac condition) + I49.01 (VF). On CPR and critical care time: 92950 and 99291 are reportable together on the same date, but the actual minutes spent performing CPR must be deducted from the total critical care time before applying the 30-minute threshold — including CPR minutes in the critical care time total is a documentation and compliance error per AMA CPT and NCCI guidelines. Separately: 92960 (cardioversion) must NEVER be reported alongside 92950 for the same episode — elective cardioversion and emergency defibrillation-as-CPR-component are mutually exclusive claims for the same encounter. Finally, G93.1 (anoxic brain damage) remains one of the most under-coded post-arrest diagnoses in inpatient settings — it dramatically affects DRG severity and should be queried whenever the physician documents post-arrest neurological changes, altered consciousness, or hypoxic encephalopathy after ROSC.
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