Heart failure and the risk of shocks in patients with implantable cardioverter defibrillators: results from the Triggers Of Ventricular Arrhythmias (TOVA) study.
BACKGROUND
Left ventricular ejection fraction (LVEF) predicts device discharges in patients with implantable cardioverter-defibrillators (ICDs). The relationship between severity of congestive heart failure (CHF) and ICD discharges is less clear.


RESULTS
We prospectively analyzed the association between CHF and risk of appropriate ICD discharges in the Triggers Of Ventricular Arrhythmias (TOVA) study, a cohort study of ICD patients conducted at 31 centers in the United States. Reported shocks were confirmed for sustained ventricular tachycardia (VT) or fibrillation (VF) by analysis of stored electrograms. Proportional hazards models included CHF categorized by New York Heart Association class. Baseline CHF was present among 502 (44%) of 1140 patients; 170 (34%) had class I, 230 (46%) had class II, 97 (19%) had class III, and only 5 (1%) had class IV symptoms. During median follow-up of 212 days, 92 patients experienced 1 or more appropriate ICD discharges. Class III CHF was associated in a statistically significantly manner with ICD discharge for VT/VF (hazard ratio 2.40, 95% CI 1.16 to 4.98), even with adjustment for LVEF. The combination of LVEF <0.20 and class III symptoms resulted in a particularly high risk of shocks for VT/VF (hazard ratio 3.90, 95% CI 1.28 to 11.92).


CONCLUSIONS
Class III CHF, an easily accessible clinical measure, is an independent risk factor, along with LVEF, for ventricular arrhythmias that require shock therapy among ICD patients. Whether patients with class III CHF benefit to a greater degree from ICDs and whether aggressive treatment of CHF in ICD patients may prevent ventricular arrhythmias remains to be determined.
Whang
William
W
Cardiovascular Division, Bulfinch 001, Massachusetts General Hospital, 55 Fruit St, Boston, Mass 02114, USA. wwhang@partners.org
Mittleman
Murray A
MA
Rich
David Q
DQ
Wang
Paul J
PJ
Ruskin
Jeremy N
JN
Tofler
Geoffrey H
GH
Muller
James E
JE
Albert
Christine M
CM
D000206:Actuarial Analysis; D000368:Aged; D002317:Cardiovascular Agents / Q000627:therapeutic use; D016757:Death, Sudden, Cardiac / Q000517:prevention & control; D017147:Defibrillators, Implantable / Q000706:statistics & numerical data*; D018572:Disease-Free Survival; D004554:Electric Countershock / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006333:Heart Failure / Q000150:complications* / Q000188:drug therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D011237:Predictive Value of Tests; D016016:Proportional Hazards Models; D011446:Prospective Studies; D012306:Risk; D012307:Risk Factors; D012720:Severity of Illness Index; D013318:Stroke Volume; D017180:Tachycardia, Ventricular / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control / Q000628:therapy; D014481:United States / Q000453:epidemiology; D014693:Ventricular Fibrillation / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control / Q000628:therapy
D002317:Cardiovascular Agents