CARDIOVASCULAR MEDICINE

Excessive breathlessness in patients with diastolic heart failure

K K A Witte, N P Nikitin, J G F Cleland and A L Clark

Department of Academic Cardiology, Castle Hill Hospital, Kingston upon Hull, UK

Correspondence to:
Correspondence to:
Dr Klaus Witte
Academic Cardiology, Castle Hill Hospital, Castle Road, Cottingham, Hull HU16 5JQ, UK; klauswitte{at}hotmail.com

Objectives: To establish the prevalence of preserved left ventricular (LV) systolic function (PSF) in 435 consecutive symptomatic patients referred to a heart failure clinic and to examine their ventilatory response to exercise when compared with 134 control volunteers.

Methods: 216 (50%) patients had systolic heart failure (SHF) (ejection fraction < 45%). 51 (11%) had an immediately apparent alternative causes of breathlessness and 168 (39%), with no obvious other cause of breathlessness, were divided into those with PSF and diastolic dysfunction (DD) (PSF_DD; n = 113 or 26% of referrals) and those without DD (PSF_N; n = 55 or 13% of referrals). The controls were divided into those with (C_DD; n = 32) and those without (C_N; n = 102) echocardiographic evidence of DD.

Results: Patients with SHF had lower peak oxygen consumption (pO₂), steeper slope of minute ventilation (E) to carbon dioxide production, lower exercise time and shorter 6 min walk test than PSF patients and controls. PSF_DD patients had lower pO₂, exercise time and 6 min walk test than C_DD, although their echocardiograms were not different. Exercise capacity did not differ between PSF_DD and PSF_N patients. The slope relating E to symptoms (Borg/E slope) was less steep in those with SHF than in PSF_DD (0.17 (0.04) v 0.20 (0.08), p < 0.05) and in PSF_N (0.19 (0.10), p < 0.05), implying greater symptoms of breathlessness for a given level of E. Both PSF groups had a steeper slope than C_DD (0.14 (0.09), p < 0.05 for both comparisons).

Conclusions: Patients with PSF have exercise tolerance intermediate between that of patients with SHF and controls. Exercise tolerance is similar in PSF_DD and PSF_N. Both groups have worse exercise tolerance than C_DD. PSF_DD and PSF_N patients seem to experience a greater awareness of E than C_DD and patients with SHF.

Abbreviations: C_DD, controls with diastolic dysfunction; C_N, controls with normal diastolic function; DD, diastolic dysfunction; DHF, diastolic heart failure; IVRT, isovolumic relaxation time; LV, left ventricular; NYHA, New York Heart Association; PSF, preserved systolic function; PSF_DD, preserved systolic function and diastolic dysfunction; PSF_N, preserved systolic function without diastolic dysfunction; pO₂, peak oxygen consumption; SHF, systolic heart failure; CO₂, carbon dioxide production; E, minute ventilation

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