Combined assessment of heart rate recovery and T-wave alternans during routine exercise testing improves prediction of total and cardiovascular mortality: the Finnish Cardiovascular Study.
BACKGROUND
Identification of individuals who are at risk for cardiovascular death remains a pressing public health challenge. Derangements in autonomic function acting upon an electrically unstable substrate are thought to be critical elements in triggering cardiovascular events.


OBJECTIVE
The purpose of this study was to analyze heart rate recovery (HRR) in combination with T-wave alternans (TWA) to improve risk assessment.


METHODS
The Finnish Cardiovascular Study (FINCAVAS) enrolled consecutive patients (N = 1,972 [1,254 men and 718 women], age 57 +/- 13 years [mean +/- SD]) with a clinically indicated exercise test using bicycle ergometer. TWA was analyzed continuously with the time-domain modified moving average method. Maximum TWA at heart rates <125 bpm was derived.


RESULTS
During 48 +/- 13 months of follow-up (mean +/- SD), 116 patients died; 55 deaths were cardiovascular. In multivariable Cox analysis after adjustment for common coronary risk factors, high exercise-based TWA (> or =60 microV) and low HRR (< or =18 bpm) yielded relative risks for all-cause mortality of 5.0 (95% confidence 2.1-12.1, P <.01) and for cardiovascular mortality of 12.3 (95% confidence interval 4.3-35.3, P <.01). High recovery-based TWA (> or =60 microV) and low HRR (< or =18 bpm) yielded relative risks for all-cause death of 6.1 (95% confidence interval 2.8-13.2, P <.01) and for cardiovascular mortality of 8.0 (95% confidence interval 2.9-22.0, P <.01). Prediction by HRR and TWA, both singly and in combination, exceeded that of standard cardiovascular risk factors.


CONCLUSIONS
Reduced HRR and heightened TWA powerfully predict risk for cardiovascular and all-cause death in a low-risk population. This novel approach could aid in screening of general populations during routine exercise protocols as well as improve insights into pathophysiology.
Leino
Johanna
J
Medical School, University of Tampere, Tampere, Finland.
Minkkinen
Mikko
M
Nieminen
Tuomo
T
Lehtimäki
Terho
T
Viik
Jari
J
Lehtinen
Rami
R
Nikus
Kjell
K
Kööbi
Tiit
T
Turjanmaa
Väinö
V
Verrier
Richard L
RL
Kähönen
Mika
M
D000222:Adaptation, Physiological; D001642:Bicycling / Q000502:physiology; D002318:Cardiovascular Diseases / Q000453:epidemiology / Q000401:mortality* / Q000503:physiopathology; D016552:Ergometry; D005080:Exercise Test; D005260:Female; D005387:Finland / Q000453:epidemiology; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D011379:Prognosis; D016016:Proportional Hazards Models; D012306:Risk; D012307:Risk Factors; D013318:Stroke Volume; D016277:Ventricular Function, Left