Table 4.

The main studies evaluating the prognostic significance of heart rate turbulence and risk stratification

Ref.	Clinical setting	Number of patients	Cut-off proposed	End-points (mean follow-up)	Results
Schmidt et al[80], 1999	Postinfarction patients	577	TO 0% TS 2.5 ms/RR	All-cause mortality (follow-up 22 mo)	HRT2 predictive for all-cause mortality
Ghuran et al[81], 2002	Postinfarction patients (ATRAMI)	1212	TO 0% TS 2.5 ms/RR	Combined end-point of fatal and non fatal cardiac arrhythmias (follow-up 21 mo)	HRT associated with endpoints
Barthel et al[83], 2003	Postinfarction patients (ISAR-HRT)	1455	TO 0% TS 2.5 ms/RR	All-cause mortality (follow-up 22 mo)	HRT independent predictor of mortality in patients with LVEF ≥ 30%
Grimm et al[84], 2003	NIDCM, LVEF ≤ 30%	242	TO 0% TS 2.5 ms/RR	Transplant-free survival (follow-up: 41 mo)	TO predictor of transplant-free survival. TO and TS only as univariate predictor of MCE
Exner et al[85], 2007	Myocardial infarction (REFINE)	322	TO 0% TS 2.5 ms/RR	Cardiac death or resuscitated cardiac arrest (follow-up 47 mo)	HRT (10-14 wk after MI) predictive for cardiac death or resuscitated cardiac arrest
Cygankiewicz et al[86], 2008	CHF (IDCM/and NIDCM)	607	TO 0% TS 2.5 ms/RR	All-cause mortality, sudden death and heart failure death (follow-up: 44 mo)	Abnormal TS predictive for all-cause mortality, sudden death and heart failure death
Klingenheben et al[87], 2008	NIDCM (Mean LVEF 28%)	114	TO 0% TS 2.5 ms/RR	Arrhythmic events (follow-up 22 mo)	HRT non predictive for arrhythmic events
Miwa et al[88], 2009	IDCM (241) and NIDCM (134)	375	TO 0% TS 2.5 ms/RR	Cardiac mortality Combined endpoint of cardiac death and/or stable sustained VT (follow-up 15 mo)	Abnormal HRT predictive for cardiac mortality and combined endpoint Prognostic value observed in both ischemic and non-ischemic cardiomyopathy
Huikuri et al[89], 2009	Postinfarction CARISMA	312	TS 2.5 ms/RR	Primary endpoint of documented VT/TV (follow-up 2 yr)	TS evaluated at 6 wk after MI predictive for primary endpoint No prognostic value for HRT evaluated 1 wk after MI
Ikeda et al[90], 2011	NIDC	134	TO 0% TS 2.5 ms/RR	Combined endpoint of cardiac mortality and sustained VT (follow-up 15 mo)	Abnormal HRT predictive for combined endpoint
Miwa et al[91], 2012	IDCM / NIDCM (LVEF ≤ 40%)	299	TO 0% TS 2.5 ms/RR	Combined endpoint of sudden cardiac death and sustained VT (follow-up 32 mo)	Abnormal HRT predictive for combined endpoint

HRT: Heart rate turbulence; NIDCM: Non-ischemic dilated cardiomyopathy; TO: Turbulence onset; TS: Turbulence slope; MCE: Major cardiac events; LVEF: Left ventricular ejection fraction; CHF: Chronic heart failure; NYHA ICD: Implantable cardioverter defibrillator.