Myocardial oxygen supply and demand imbalance predicts mortality in older nursing home residents: The PARTAGE study.

BACKGROUND: A mismatch between myocardial oxygen supply and demand is the most common cause of ischemic myocardial injury in older persons. The subendocardial viability ratio (SEVR) can usefully estimate the degree of myocardial perfusion relative to left-ventricular workload. The aim of the present study was to evaluate the ability of SEVR to predict long-term mortality in the older population. Additionally, we aimed to identify the SEVR cutoff value best predicting total mortality. METHODS: This is a multicenter, longitudinal study involving a large population of individuals older than 80 years living in nursing homes. Patients with cancer, severe dementia, and very low level of autonomy were excluded from the study. Participants were monitored for 10 years. Adverse outcomes were recorded every 3 months from inclusion to the end of the study. SEVR reflects the balance between subendocardial oxygen supply and demand, and was estimated non-invasively by analyzing the carotid pressure waveform recorded by applanation arterial tonometry. RESULTS: A total of 828 people were enrolled (mean age: 87.7 ± 4.7 years, 78% female). 735 patients died within 10 years and 24 were lost to follow-up. SEVR was inversely associated with mortality at univariate Cox-regression model (risk ratio, 0.683 per unit increase in SEVR; 95% confidence interval (CI) [0.502-0.930], p = 0.015) and in a model including age, sex, body mass index, Activity of Daily Living index and Mini-Mental State Examination score (risk ratio, 0.647; 95% CI [0.472-0.930]). The lowest tertile of SEVR was associated with higher 10-years total mortality than the middle (p < 0.001) and the highest (p < 0.004) tertile. A SEVR cutoff value of 83% was identified as the best predictor of total mortality. CONCLUSIONS: SEVR may be considered as a marker of "cardiovascular frailty." An accurate non-invasive estimation of SEVR could be a useful and independent parameter to assess survival probability in very old adults. TRIAL REGISTRATION: NCT00901355, registered on ClinicalTrials.gov website.

Comparison Between Invasive and Noninvasive Methods to Estimate Subendocardial Oxygen Supply and Demand Imbalance.

Background Estimation of the balance between subendocardial oxygen supply and demand could be a useful parameter to assess the risk of myocardial ischemia. Evaluation of the subendocardial viability ratio (SEVR, also known as Buckberg index) by invasive recording of left ventricular and aortic pressure curves represents a valid method to estimate the degree of myocardial perfusion relative to left ventricular workload. However, routine clinical use of this parameter requires its noninvasive estimation and the demonstration of its reliability. Methods and Results Arterial applanation tonometry allows a noninvasive estimation of SEVR as the ratio of the areas directly beneath the central aortic pressure curves obtained during diastole (myocardial oxygen supply) and during systole (myocardial oxygen demand). However, this "traditional" method does not account for the intra-ventricular diastolic pressure and proper allocation to systole and diastole of left ventricular isometric contraction and relaxation, respectively, resulting in an overestimation of the SEVR values. These issues are considered in the novel method for SEVR assessment tested in this study. SEVR values estimated with carotid tonometry by "traditional" and "new" method were compared with those evaluated invasively by cardiac catheterization. The "traditional" method provided significantly higher SEVR values than the reference invasive SEVR: average of differences±SD= 44±11% (limits of agreement: 23% - 65%). The noninvasive "new" method showed a much better agreement with the invasive determination of SEVR: average of differences±SD= 0±8% (limits of agreement: -15% to 16%). Conclusions Carotid applanation tonometry provides valid noninvasive SEVR values only when all the main factors determining myocardial supply and demand flow are considered.

Systolic time intervals assessed from analysis of the carotid pressure waveform.

OBJECTIVE: The timing of mechanical cardiac events is usually evaluated by conventional echocardiography as an index of cardiac systolic function and predictor of cardiovascular outcomes. We aimed to measure the systolic time intervals, namely the isovolumetric contraction time (ICT) and pre-ejection period (PEP), by arterial tonometry. APPROACH: Sixty-two healthy volunteers (age 47 ± 17 years) and 42 patients with heart failure and reduced ejection fraction were enrolled (age 66 ± 14 years). Pulse waves were recorded at the carotid artery by arterial tonometry together with simultaneous aortic transvalvular flow by Doppler-echocardiography, synchronized by electrocardiographic gating. The ICT was determined from the time delay between the electrical R wave and the carotid pressure waveform, after adjustment for the pulse transit time from the aortic valve to the carotid artery site, estimated by an algorithm based on the carotid-femoral pulse wave velocity. The PEP was evaluated by adding the electrical QR duration to the ICT. MAIN RESULTS: The ICT derived from carotid pulse wave analysis was closely related to that measured by echocardiography (r = 0.90, p < 0.0001), with homogeneous distribution in Bland-Altman analysis (mean difference and 95% confidence interval = 0.2 from -14.2 to 14.5 ms). ICT and PEP were higher in cardiac patients than in healthy volunteers (p < 0.0001). The ratio between PEP and left ventricular ejection time was related to the ejection fraction measured with echocardiography (r = 0.555, p < 0.0001). SIGNIFICANCE: The timing of electro-mechanical cardiac events can be reliably obtained from the carotid pulse waveform and carotid-femoral PWV, evaluated using arterial tonometry. Systolic time intervals assessed with this approach showed good agreement with measurements performed with conventional echocardiography and may represent a promising additional application of arterial tonometry.

Influence of carotid atherosclerotic plaques on pulse wave assessment with arterial tonometry.

OBJECTIVE: Aortic stiffness and central pressure measurements have become increasingly important for the overall estimation of cardiovascular risk. The aim of this study is to verify whether the presence of stenosis in the carotid arteries due to atherosclerotic plaques may induce a bias in the measurement of carotid-femoral pulse wave velocity (PWV) and in the analysis of central pulse waveform variables assessed by carotid tonometry. METHODS: Eighty-four patients (age: 67.1 ±â€Š12.4 years) undergoing screening for carotid atherosclerosis were enrolled, divided into three groups according to carotid ultrasound findings (NASCET criteria): 28 patients without significant stenosis, 30 patients with bilateral plaques, and 26 patients with right or left monolateral stenosis. PWV and other variables derived from the central pulse waveform analysis (central blood pressure, augmentation index and forward and backward waves) were measured at both right and left carotid arteries by a validated PulsePen tonometer. A repeatability study was performed in 28 young healthy patients (age: 25.4 ±â€Š2.9 years). RESULTS: A high degree of correlation was found between bilateral measurements in all groups, and particularly in groups with monolateral carotid stenosis, with no significant difference attributable to lateralized stenosis. Right-left differences in asymmetric groups were 0.35 ±â€Š5.12 mmHg (R = 0.960) for central blood pressure, -2.12 ±â€Š7.39% (R = 0.743) for augmentation index, 0.64 ±â€Š1.56 m/s (R = 0.947) for PWV, 0.08 ±â€Š8.48 mmHg for forward wave (R = 0.742) and 0.35 ±â€Š2.35 mmHg for backward wave (R = 0.907). CONCLUSION: Measurement of PWV and of variables derived from the central pulse waveform analysis by carotid tonometry is not biased by the presence of local atherosclerotic plaques.