Table 1.

Adverse event severity level definitions with examples of adverse events which occurred during endomyocardial biopsy procedures.

Severity Level	Description	Example
Level 1 – None	No harm, no change in condition, may have required monitoring to assess for potential change in condition with no intervention indicated.	Transient bradycardia during biopsy sampling.
Level 2 – Minor	Transient change in condition, not life threatening, condition returns to baseline, required monitoring, required minor intervention such as holding a medication or obtaining a laboratory test.	Transient ST-T wave changes after coronary angiography requiring further monitoring.
Level 3 – Moderate	Transient change in condition may be life threatening if not treated, condition returns to baseline, required monitoring, required intervention such as reversal agent, additional medication, transfer to the intensive care unit for monitoring, or moderate transcatheter intervention to correct condition.	Damage to the tricuspid valve apparatus that required unexpected hospitalization for observation.
Level 4 – Major	Change in condition, life threatening if not treated, change in condition may be permanent, may have required an intensive care unit admission or emergent readmission to hospital, may have required invasive monitoring, required interventions such as electrical cardioversion or unanticipated intubation, or required major invasive cases or transcatheter interventions to correct condition.	Myocardial perforation requiring emergent pericardiocentesis.
Level 5 – Catastrophic	Any death and emergent surgery or extracorporeal membrane oxygenation (ECMO) to prevent death with failure to wean from bypass support.	A patient who developed hemodynamic instability, was placed on ECMO and subsequently died.