Evolution of clinical diagnosis in patients presenting with unexplained cardiac arrest or syncope due to polymorphic ventricular tachycardia.
BACKGROUND
A systematic evaluation of patients with unexplained cardiac arrest (UCA) yields a diagnosis in 50% of the cases. However, evolution of clinical phenotype, identification of new disease-causing mutations, and description of new syndromes may revise the diagnosis.


OBJECTIVE
To assess the evolution in diagnosis among patients with initially UCA.


METHODS
Diagnoses were reviewed for all patients with UCA recruited from the Cardiac Arrest Survivors with Preserved Ejection Fraction Registry with at least 1 year of follow-up.


RESULTS
After comprehensive investigation of 68 patients (age 45.2 ± 14.9 years; 63% men), the initial diagnosis was as follows: idiopathic ventricular fibrillation (n = 34 [50%]), a primary arrhythmic disorder (n = 21 [31%]), and an occult structural cause (n = 13 [19%]). Patients were followed for 30 ± 17 months, during which time the diagnosis changed in 12 (18%) patients. A specific diagnosis emerged for 7 patients (21%) with an initial diagnosis of idiopathic ventricular fibrillation. A structural cardiomyopathy evolved in 2 patients with an initial diagnosis of primary electrical disorder, while the specific structural cardiomyopathy was revised for 1 patient. Two patients with an initial diagnosis of a primary arrhythmic disorder were subsequently considered to have a different primary arrhythmic disorder. A follow-up resting electrocardiogram was the test that most frequently changed the diagnosis (67% of the cases), followed by genetic testing (17%).


CONCLUSIONS
The reevaluation of patients presenting with UCA may lead to a change in diagnosis in up to 20%. This emphasizes the need to actively monitor the phenotype and also has implications for the treatment of these patients and the screening of their relatives.
Population Health Research Institute, McMaster University, Hamilton, Canada; Polytechnic University of Marche, Ancona, Italy.
Maria
M
Vittoria Matassini
University of British Columbia, Vancouver, British Columbia, Canada.
Andrew D
AD
Krahn
Dalhousie University, Halifax, Nova Scotia, Canada.
Martin
M
Gardner
Université Laval, Quebec City, Quebec, Canada.
Jean
J
Champagne
British Columbia Children's Hospital, Vancouver, British Columbia, Canada.
Shubhayan
S
Sanatani
University of Ottawa Heart Institute, Ottawa, Canada.
David H
DH
Birnie
University of Ottawa Heart Institute, Ottawa, Canada.
Michael H
MH
Gollob
University Health Network, University of Toronto, Toronto, Ontario, Canada.
Vijay
V
Chauhan
Queen's University, Kingston, Ontario, Canada.
Christopher S
CS
Simpson
Hospital for Sick Children, Toronto, Ontario, Canada.
Robert M
RM
Hamilton
Montreal Heart Institute, Montreal, Quebec, Canada.
Mario
M
Talajic
St. Michael's Hospital, University of Toronto, Toronto, Ontario, Canada.
Kam
K
Ahmad
University of Calgary, Calgary, Alberta, Canada.
Brenda
B
Gerull
University of British Columbia, Vancouver, British Columbia, Canada.
Santabhanu
S
Chakrabarti
Population Health Research Institute, McMaster University, Hamilton, Canada. Electronic address: Jeff.Healey@phri.ca.
Jeff S
JS
Healey
D000328:Adult; D001145:Arrhythmias, Cardiac / Q000175:diagnosis; D009202:Cardiomyopathies / Q000175:diagnosis; D003937:Diagnosis, Differential; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006323:Heart Arrest / Q000175:diagnosis*; D006801:Humans; D008133:Long QT Syndrome / Q000175:diagnosis; D008297:Male; D008875:Middle Aged; D012042:Registries; D013575:Syncope / Q000175:diagnosis*; D017180:Tachycardia, Ventricular / Q000150:complications*; D014693:Ventricular Fibrillation / Q000175:diagnosis
ARVC; CASPER; CPVT; Cardiac Arrest Survivors with Preserved Ejection Fraction Registry; Cardiac arrest; ECG; ERS; Genetics; IVF; LQTS; QTc; Registry; SAECG; SS; Schwartz score; UCA; VT; arrhythmogenic right ventricular cardiomyopathy; catecholaminergic polymorphic ventricular tachycardia; corrected QT interval; early repolarization syndrome; electrocardiogram/electrocardiographic; idiopathic ventricular fibrillation; long QT syndrome; signal-averaged electrocardiography; unexplained cardiac arrest; ventricular tachycardia