Chronotropic Incompetence Does Not Limit Exercise Capacity in Chronic Heart Failure.
BACKGROUND
Limited heart rate (HR) rise (HRR) during exercise, known as chronotropic incompetence (CI), is commonly observed in chronic heart failure (CHF). HRR is closely related to workload, the limitation of which is characteristic of CHF. Whether CI is a causal factor for exercise intolerance, or simply an associated feature remains unknown.


OBJECTIVE
This study sought to clarify the role of the HR on exercise capacity in CHF.


METHODS
This series of investigations consisted of a retrospective cohort study and 2 interventional randomized crossover studies to assess: 1) the relationship between HRR and exercise capacity in CHF; and 2) the effect of increasing and lowering HR on exercise capacity in CHF as assessed by symptom-limited treadmill exercise testing and measurement of peak oxygen consumption in patients with CHF due to left ventricular systolic dysfunction.


RESULTS
The 3 key findings were: 1) the association of exercise capacity and HRR is much weaker in severe CHF compared to normal left ventricular function; 2) increasing HRR using rate-adaptive pacing (versus fixed-rate pacing) in unselected patients with CHF does not improve peak exercise capacity; and 3) acutely lowering baseline and peak HR by adjusting pacemaker variables in conjunction with a single dose of ivabradine does not adversely affect exercise capacity in unselected CHF patients.


CONCLUSIONS
The data refute the contention that CI contributes to impaired exercise capacity in CHF. This finding has widespread implications for pacemaker programming and the use of heart-rate lowering agents. (The Influence of Heart Rate Limitation on Exercise Tolerance in Pacemaker Patients [TREPPE]; NCT02247245).
Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom.
Haqeel A
HA
Jamil
Clinical Trials Research Unit, Leeds Institute of Clinical Trials Research, Leeds, United Kingdom.
John
J
Gierula
Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom.
Maria F
MF
Paton
Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom.
Roo
R
Byrom
Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom.
Judith E
JE
Lowry
Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom.
Richard M
RM
Cubbon
Clinical Trials Research Unit, Leeds Institute of Clinical Trials Research, Leeds, United Kingdom.
David A
DA
Cairns
Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom.
Mark T
MT
Kearney
Leeds Institute of Cardiovascular and Metabolic Medicine, University of Leeds, Leeds, United Kingdom. Electronic address: k.k.witte@leeds.ac.uk.
Klaus K
KK
Witte
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D002316:Cardiotonic Agents / Q000008:administration & dosage / Q000494:pharmacology; D016009:Chi-Square Distribution; D002908:Chronic Disease; D015331:Cohort Studies; D016001:Confidence Intervals; D004452:Echocardiography; D005081:Exercise Therapy / Q000379:methods*; D017079:Exercise Tolerance / Q000502:physiology*; D005260:Female; D006333:Heart Failure / Q000000981:diagnostic imaging / Q000188:drug therapy / Q000401:mortality / Q000534:rehabilitation*; D006339:Heart Rate / Q000187:drug effects*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology; D011379:Prognosis; D016032:Randomized Controlled Trials as Topic; D012016:Reference Values; D012189:Retrospective Studies; D018570:Risk Assessment; D012720:Severity of Illness Index; D012737:Sex Factors; D015996:Survival Rate
D002316:Cardiotonic Agents
chronotropic incompetence; exercise capacity; heart failure; heart rate