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Left ventricular global dyssynchrony is exaggerated with age
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology.
Umeå University, Faculty of Medicine, Department of Surgical and Perioperative Sciences, Clinical Physiology. (Heart Centre)
Umeå University, Faculty of Medicine, Department of Public Health and Clinical Medicine, Cardiology. (Heart Centre)
2013 (English)In: International Cardiovascular Forum, ISSN 2410-2636, Vol. 1, no 1, 47-51 p.Article in journal (Refereed) Published
Abstract [en]

Background and Aim. Total isovolumic time (t-IVT) and Tei index both reflect global left ventricular (LV) dyssynchrony. They have been shown to be sensitive in responding to myocardial revascularization and in predicting clinical outcome in heart failure patients. Since most these patients are senior, determining the exact effect of age on such parameters remains mandatory. The aim of this study was to investigate the effect of age on LV t-IVT and Tei index compared with conventional systolic and diastolic parameters in normal individuals.

Methods. We studied 47 healthy individuals, mean age 62±12 years (24 female), who were arbitrarily classified into three groups: M (middle age), S (seniors), and E (elderly), using spectral Doppler echocardiography and tissue-Doppler imaging. We studied the interrelation between age, LV systolic and diastolic function parameters as well as t-IVT [60 – (total ejection time + total filling time) in s/min], and Tei index (T-IVT/ejection time).

Results. LV ejection fraction was 68±6%, E/A ratio 1±0.4, filling time 538±136ms, ejection time 313±26ms, t-IVT 7.7±2.6 s/min and Tei index 0.41±0.14. Age strongly correlated with t-IVT (r=0.8, p<0.001) and with Tei index (r=0.7, p<0.001) but not with QRS duration. Age also correlated with E/A ratio (r=-0.6, p<0.001), but not with global or segmental systolic function measurements. Mean values for t-IVT were 5.5 (95% CI, 4.6-6.3 s/min) for M, 6.9 (95% CI, 6.0-7.8 s/min) for S and 9.5 (95% CI, 8.4-10.6 s/min) for E groups. The corresponding upper limit of the t-IVT 95% normal CI (calculated as mean ±2SD) for the three groups was 8.3 s/min, 10.5 s/min and 14.5 s/min, respectively. The upper limit of normal t-IVT 95% CI was significantly shorter in the S compared with the E group (p=0.001). T-IVT correlated with A wave (r=0.66, p<0.001), E/A ratio (r=-0.56, p<0.001), septal e’ (r=-0.49, p=0.001) and septal a’ (r=0.4, p=0.006), but not with QRS.

Conclusions. In normals, age is associated with exaggerated LV global dyssynchrony and diastolic function disturbances, but systolic function remains unaffected. The strong relationship between age and t-IVT supports its potential use as a marker of global LV dyssynchrony. In addition, variations in the upper limit of normal values, particularly in the elderly may have significant clinical applications in patients recommended for CRT treatment.

Place, publisher, year, edition, pages
Barcaray International Publishing , 2013. Vol. 1, no 1, 47-51 p.
Keyword [en]
Total isovolumic time, age, LV dyssynchrony, Doppler echocardiography
National Category
Cardiac and Cardiovascular Systems
Research subject
Cardiology
Identifiers
URN: urn:nbn:se:umu:diva-88469OAI: oai:DiVA.org:umu-88469DiVA: diva2:715828
Available from: 2014-05-06 Created: 2014-05-06 Last updated: 2015-08-24Bibliographically approved
In thesis
1. The clinical value of total isovolumic time
Open this publication in new window or tab >>The clinical value of total isovolumic time
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The objective of this thesis is to evaluate the use of Doppler echocardiography markers ofglobal dyssynchrony [total isovolumic time (t-IVT)] in the following 6 studies: 1) Its prognostic role in predicting cardiac events in patients undergoing CABG surgery,compared with conventional global systolic and diastolic measurements. 2) Its additional value in predicting six minute walk test (6-MWT) in patients with leftventricular (LV) ejection fraction (EF) <45%. 3) Its prognostic value in comparison with other clinical, biochemical and echocardiographicvariables in patients with chronic systolic heart failure (HF). 4) The relationship between 6-MWT and cardiac function measurements in a consecutivegroup of patients, irrespective of EF and to identify predictors of exercise capacity. 5) To investigate the effect of age on LV t-IVT and Tei index compared with conventionalsystolic and diastolic parameters. 6) To assess potential additional value of markers of global LV dyssynchrony in predictingcardiac resynchronization therapy (CRT) response in HF patients.

Study I

Methods: This study included 74 patients before routine CABG who were followed up for18±12 months. Results: At follow-up, 29 patients were hospitalized for a cardiac event or died. LV-ESD wasgreater (P=0.003), fractional shortening (FS) lower (p<0.001), E:A ratio and Tei index higher(all P<0.001), and t-IVT longer (P<0.001) in patients with events. Low FS [0.66 (0.50–0.87),P<0.001], high E:A ratio [l4.13 (1.17–14.60), P=0.028], large LV-ESD [0.19 (0.05–0.84),P=0.029], and long t-IVT [1.37 (1.02–1.84), P=0.035] predicted events and deaths. Conclusion: Despite satisfactory surgical revascularization, long t-IVT and systolicdysfunction suggest persistent ventricular dyssynchrony that contributes to post-CABGcardiac events.

Study II

Methods: We studied 77 patients (60±12 year, and 33.3% females) with stable HF using 6-MWT.iii Results: E’ wave (r=0.61, p<0.001), E/e’ ratio (r=-0.49, p<0.001), t-IVT (r=-0.44, p<0.001),Tei index (r=-0.43, p<0.001) and NYHA class (r=-0.53, p<0.001) had the highest correlationwith the 6-MWT distance. In multivariate analysis, only E/e’ ratio [0.800 (0.665-0.961),p=0.017], and t-IVT [0.769 (0.619-0.955), p=0.018] independently predicted poor 6-MWTperformance (<300m). Conclusions: In HF, the higher the filling pressures and the more dyssynchronous the LV, thepoorer is the patient’s exercise capacity.

Study III

Methods: We studied 107 systolic HF patients; age 68±12 year, 25% females and measuredplasma NT-pro-BNP. Results: Over a follow-up period of 3718 months, t-IVT ≥12.3 sec/min, mean E/Em ratio≥10, log NT-pro-BNP levels ≥2.47 pg/ml and LV EF ≤32.5% predicted clinical events. Theaddition of t-IVT and NT-pro-BNP to conventional clinical and echocardiographic variablessignificantly improved the χ2 for the prediction of outcome from 33.1 to 38.0, (p<0.001). Conclusions: Prolonged t-IVT adds to the prognostic stratification of patients with systolicHF.

Study IV

Methods: We studied 147 HF patients (61±11 year, 50.3% male) with 6-MWT.Results: The 6-MWT correlated with t-IVT (r=-0.49, p<0.001) and Tei index (r=-0.43,p<0.001) but not with any of the other clinical or echocardiographic parameters. Group Ipatients (<300m) had lower Hb (p=0.02), lower EF (p=0.003), larger left atrium (p=0.02),thicker septum (p=0.02), lower A wave (p=0.01) and lateral wall a’ (p=0.047), longerisovolumic relaxation time (r=0.003) and longer t-IVT (p= 0.03), compared with Group II(>300m). Only t-IVT ratio [1.257 (1.071-1.476), p=0.005], LV EF [0.947 (0.903-0.993),p=0.02], and E/A ratio [0.553 (0.315-0.972), p=0.04] independently predicted poor 6-MWTperformance. Conclusion: In HF, the limited 6-MWT is related mostly to severity of global LVdyssynchrony, more than EF or raised filling pressures.

Study V

Methods: We studied 47 healthy individuals (age 62±12 year, 24 female), arbitrarilyclassified into: M (middle age), S (seniors), and E (elderly). Results: Age strongly correlated with t-IVT (r=0.8, p<0.001) and with Tei index (r=0.7,p<0.001), E/A ratio (r=-0.6, p<0.001), but not with global or segmental systolic function measurements or QRS duration. The normal upper limit of the t-IVT (95% CI) for the three groups was 8.3 s/min, 10.5 s/min and 14.5 s/min, respectively, being shorter in the S compared with the E group (p=0.001). T-IVT correlated with A wave (r=0.66, p<0.001), E/Aratio (r=-0.56, p<0.001), septal e’ (r=-0.49, p=0.001) and septal a’ (r=0.4, p=0.006), but notwith QRS. Conclusions: In normals, age is associated with exaggerated LV global dyssynchrony anddiastolic function disturbances, but systolic function remains unaffected.

Study VI

Methods: We studied 103 HF patients (67±12 year, 82.5% male) recruited for CRTtreatment. Results: Prolonged t-IVT [0.878 (0.802-0.962), p=0.005], long QRS duration [0.978 (0.960-0.996), p=0.02] and high tricuspid regurgitation pressure drop (TRPD) [1.047 (1.001-1.096),p=0.046] independently predicted response to CRT. A t-IVT ≥11.6 s/min was 67% sensitiveand 62% specific (AUC 0.69, p=0.001) in predicting CRT response. Respective values for aQRS ≥ 151ms were 66% and 62% (AUC 0.65, p=0.01). Combining the two variables had asensitivity of 67% but higher specificity of 88% in predicting CRT response. In atrialfibrillation (AF) patients, only prolonged t-IVT ≥11 s/min [0.690 (0.509-0.937), p=0.03]independently predicted CRT response with a sensitivity of 69% and specificity of 79% (AUC0.78, p=0.015). Conclusion: Combining prolonged t-IVT and broad QRS had higher specificity in predictingresponse to CRT, with the former the sole predictor of response in AF patients.

Place, publisher, year, edition, pages
Umeå: Umeå universitet, 2014. 89 p.
Series
Umeå University medical dissertations, ISSN 0346-6612 ; 1656
Keyword
Heart failure, cardiac resynchronization therapy, predictors, echocardiography, total isovolumic time, six-minute walk test, left ventricular dyssynchrony
National Category
Cardiac and Cardiovascular Systems
Identifiers
urn:nbn:se:umu:diva-88994 (URN)978-91-7601-086-0 (ISBN)
Public defence
2014-06-10, Room D, Unod T9, Norrlands universitetssjukhus, Umea, 09:00 (English)
Opponent
Supervisors
Available from: 2014-05-20 Created: 2014-05-19 Last updated: 2014-05-20Bibliographically approved

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