Modifiers matching arrhythmia:

• cardiac,
• severe,
• serious,
• ventricular,

Simple categories matching serious:

• disease,
• illness,
• pains,
• idea,
• circumstances,
• calamity,
• endeavor,
• violence,
• condition,
• infection,
• threat,
• crime,
• form,
• std,
• user,
• song,
• disorder,
• trouble,
• upheaval,
• interaction,
• larceny,
• participation,
• material,
• trauma,
• subject,
• offense,
• drama,
• disability,
• sector,
• ceremony,
• pathology,
• story,
• reaction,
• injury,
• offence,
• tale,
• violation,
• agent,
• misconduct,
• blemish,
• infraction,
• aberration,
• wrongdoing,
• effort,
• wound,
• failure,
• intervention,
• procedure,
• stuff,
• problem,
• forum,
• drug,
• setback,
• attack,
• diversion,
• trait,
• sickness,
• occasion,
• journal,
• topic,
• injustice,
• harm,
• complication,
• phenomenon,
• point,
• defect,
• discipline,
• malpractice,
• theme,
• hazard,
• emotion,
• science,
• zoonosis,
• misbehaviour,
• study,
• writing,
• grounds,
• profession,
• behaviour,
• loss,
• malignancy,
• case,
• complaint,
• enjoyment,
• gathering,
• tendency,
• end,
• stage,
• operation,
• scholar,
• game,
• animal,
• program,
• conflict,
• business,
• act,
• bacteria,
• pathogen,
• narcotic,
• risk,
• constraint,
• infringement,
• virus,
• damage,
• headache,
• stimulant,
• malfunction,
• accident,
• addiction,
• imperfection,
• incident,
• content,
• malady,
• surgery,
• happening,
• abnormality,
• disturbance,
• delinquent,
• charge,
• tumour,
• mishap,
• behavior,
• reader,
• dance,
• disruption,
• experience,
• item,
• piece,
• music,
• document,
• phobia,
• substance,
• enterprise,
• evil,
• nature,
• event,
• passion,
• measure,
• harassment,
• penalty,
• error,
• information,
• symptom,
• sin,
• promise,
• pain,
• attempt,
• thing,
• handicap,
• danger,
• misfortune,
• contagion,
• storm,
• result,
• title,
• application,
• professional,
• flaw,
• abuse,
• disaster,
• entity,
• weapon,
• cancer,
• works,
• action,
• morbidity,
• challenge,
• work,
• manifestation,
• issue,
• need,
• misdeed,
• sanction,
• transgression,
• help,
• situation,
• status,
• mistake,
• matter,
• difficulty,
• ailment,
• consequence,
• allergy,
• indiscipline,
• system,
• assault,
• cause,
• activity,
• casualty,
• arrhythmia,
• state,
• occurrence,
• felony,
• development,
• conduct,