Impaired left ventricular stroke volume reserve during clinical dobutamine stress predicts future episodes of pulmonary edema

Prognostic value of N-Terminal Pro-B-Type Natriuretic Peptide in Takotsubo syndrome

BACKGROUND

Takotsubo syndrome (TTS), a form of acute transient heart failure, has been associated with severe complications and considerable mortality rates. N-Terminal Pro-B-Type Natriuretic Peptide (NT-proBNP) might serve as a marker to identify high-risk patients but has not yet been investigated regarding prognostic implications in TTS. Aim of this study was to determine the short- and long-term prognostic utility of NT-proBNP in patients with TTS.

METHODS

The predictive value of admission NT-proBNP was assessed in an international, multicenter study including 177 consecutive TTS patients. Predefined endpoints were 30-day major adverse cardiac events (MACE) consisting of all-cause death, cardiogenic shock, and pulmonary edema as well as long-term mortality in median 2.3 years after the acute event.

RESULTS

Stratification according to median admission NT-proBNP (4511 pg/ml) resulted in significantly higher 30-day MACE [22.5 versus 9.1%; odds ratio (OR) 2.90, 95% confidence interval (CI) 1.20-6.99 p = 0.015] and long-term mortality rates [16.3 versus 9.4%; hazard ratio (HR) 2.72, 95% CI 1.13-6.56 p = 0.021] in patients > median. The best admission NT-proBNP cutoffs to predict 30-day MACE and long-term mortality were determined at 5560 and 8178 pg/ml respectively, with subsequent improved risk stratification for short-term MACE (OR 3.61, 95% CI 1.49-8.72; p = 0.003) and long-term mortality (HR 4.40; 95% CI 1.85-10.44, p < 0.001). Multivariate regression analysis identified admission NT-proBNP as an independent predictor of 30-day MACE (p < 0.001) and long-term mortality (p = 0.012).

CONCLUSIONS

Admission NT-proBNP is an independent predictor for short- and long-term adverse events in TTS patients and, therefore, a useful marker for risk stratification immediately at presentation.

Cardiovascular response to exercise training in the systemic right ventricle of adults with transposition of the great arteries

KEY POINTS

Patients with transposition of the great arteries (TGA) and systemic right ventricles have premature congestive heart failure; there is also a growing concern that athletes who perform extraordinary endurance exercise may injure the right ventricle. Therefore we felt it essential to determine whether exercise training might injure a systemic right ventricle which is loaded with every heartbeat. Previous studies have shown that short term exercise training is feasible in TGA patients, but its effect on ventricular function is unclear. We demonstrate that systemic right ventricular function is preserved (and may be improved) in TGA patients with exercise training programmes that are typical of recreational and sports participation, with no evidence of injury on biomarker assessment. Stroke volume reserve during exercise correlates with exercise training response in our TGA patients, identifying this as a marker of a systemic right ventricle (SRV) that may most tolerate (and possibly even be improved by) exercise training.

ABSTRACT

We aimed to assess the haemodynamic effects of exercise training in transposition of the great arteries (TGA) patients with systemic right ventricles (SRVs). TGA patients have limited exercise tolerance and early mortality due to systemic (right) ventricular failure. Whether exercise training enhances or injures the SRV is unclear. Fourteen asymptomatic patients (34 ± 10 years) with TGA and SRV were enrolled in a 12 week exercise training programme (moderate and high-intensity workouts). Controls were matched on age, gender, BMI and physical activity. Exercise testing pre- and post- training included: (a) submaximal and peak; (b) prolonged (60 min) submaximal endurance and (c) high-intensity intervals. Oxygen uptake (V̇O2; Douglas bag technique), cardiac output (Q̇c, foreign-gas rebreathing), ventricular function (echocardiography and cardiac MRI) and serum biomarkers were assessed. TGA patients had lower peak V̇O2, Q̇c, and stroke volume (SV), a blunted Q̇c/V̇O2 slope, and diminished SV response to exercise (SV increase from rest: TGA = 15.2%, controls = 68.9%, P < 0.001) compared with controls. After training, TGA patients increased peak V̇O2 by 6 ± 8.5%, similar to controls (interaction P = 0.24). The magnitude of SV reserve on initial testing correlated with Q̇c training response (r = 0.58, P = 0.047), though overall, no change in peak Q̇c was observed. High-sensitivity troponin T (hs-TnT) and N-terminal prohormone of brain naturetic peptide (NT pro-BNP) were low and did not change with acute exercise or after training. Our data show that TGA patients with SRVs in this study safely participated in exercise training and improved peak V̇O2. Neither prolonged submaximal exercise, nor high-intensity intervals, nor short-term exercise training seem to injure the systemic right ventricle.

Increased cardiovascular stiffness and impaired age-related functional status

Our objective was to determine if increased cardiovascular (CV) stiffness is associated with disability in middle-aged and older adults at risk for congestive heart failure. CV stiffness (brachial pulse pressure/left ventricular stroke volume indexed to body surface area) and total disability (the summed assessment of activities of daily living, mobility, and instrumental activities of daily living) were measured in 445 individuals. A subset of 109 randomly selected individuals also underwent physical function testing. Total disability was associated with CV stiffness (p = .01), driven by an association with mobility (p = .005), but not activities of daily living (p = .13) or instrumental activities of daily living (p = .61). After accounting for age, these correlations remained significant for men (p = .04), but not for women. CV stiffness was also associated with increased 400-m walk time (p = .02). In middle-aged and elderly men at risk for congestive heart failure, CV stiffness is associated with decreased mobility and physical function, and increased overall disability.

Mechanism of decreased sensitivity of dobutamine associated left ventricular wall motion analyses for appreciating inducible ischemia in older adults

BACKGROUND

Dobutamine associated left ventricular (LV) wall motion analyses exhibit reduced sensitivity for detecting inducible ischemia in individuals with increased LV wall thickness. This study was performed to better understand the mechanism of this reduced sensitivity in the elderly who often manifest increased LV wall thickness and risk factors for coronary artery disease.

METHODS

During dobutamine cardiovascular magnetic resonance (DCMR) stress testing, we assessed rate pressure product (RPP), aortic pulse wave velocity (PWV), LV myocardial oxygen demand (pressure volume area, PVA, mass, volumes, concentricity, and the presence of wall motion abnormalities (WMA) and first pass gadolinium enhanced perfusion defects (PDs) indicative of ischemia in 278 consecutively recruited individuals aged 69 ± 8 years with pre-existing or known risk factors for coronary artery disease. Each variable was assessed independently by personnel blinded to participant identifiers and analyses of other DCMR or hemodynamic variables.

RESULTS

Participants were 80% white, 90% hypertensive, 43% diabetic and 55% men. With dobutamine, 60% of the participants who exhibited PDs had no inducible WMA. Among these participants, myocardial oxygen demand was lower than that observed in those who had both wall motion and perfusion abnormalities suggestive of ischemia (p = 0.03). Relative to those with PDs and inducible WMAs, myocardial oxygen demand remained different in these individuals with PDs without an inducible WMA after accounting for LV afterload and contractility (p = 0.02 and 0.03 respectively), but not after accounting for either LV stress related end diastolic volume index (LV preload) or resting concentricity (p = 0.31-0.71).

CONCLUSIONS

During dobutamine stress testing, elderly patients experience increased LV concentricity and declines in LV preload and myocardial oxygen demand, all of which are associated with an absence of inducible LV WMAs indicative of myocardial ischemia. These findings provide insight as to why dobutamine associated wall motion analyses exhibit reduced sensitivity for identifying inducible ischemia in elderly.

TRIAL REGISTRATION

This study was registered with Clinicaltrials.gov (NCT00542503).

Abnormal stress-related measures of arterial stiffness in middle-aged and elderly men and women with impaired fasting glucose at risk for a first episode of symptomatic heart failure

Background

Abnormal resting arterial stiffness is present in middle‐aged and elderly persons with abnormalities of fasting glucose (diabetes or impaired fasting glucose) and is associated with exercise intolerance. We sought to determine whether these same persons exhibited stress‐related abnormalities of arterial stiffness.

Methods and Results

We analyzed dobutamine magnetic resonance stress imaging results from 373 consecutively recruited persons aged 55 to 85 years with normal fasting glucose, impaired fasting glucose, or diabetes who were at risk for but without symptomatic heart failure. Personnel blinded to participant identifiers measured arterial stiffness (brachial pulse pressure/left ventricular stroke volume indexed to body surface area, the aortic elastance index [brachial end‐systolic pressure/left ventricular stroke volume indexed to body surface area], and thoracic aortic distensibility) at 80% of the maximum predicted heart rate response for age. Participants averaged 69±8 years of age; 79% were white, 92% were hypertensive, and 66% were women. After accounting for hypertension, sex, coronary artery disease, smoking, medications, hypercholesterolemia, and visceral fat, we observed an effect of glycemic status for stress measures of arterial stiffness in those with diabetes and impaired fasting glucose relative to those with normal fasting glucose (P=0.002, P=0.02, and P=0.003, respectively).

Conclusion

Middle‐ and older‐aged individuals with diabetes or impaired fasting glucose have higher stress measures of arterial stiffness than those with normal fasting glucose. These data emphasize the need for future studies with larger sample sizes to determine whether stress‐related elevations in arterial stiffness are related to exercise intolerance and future episodes of heart failure experienced by those with abnormalities of fasting glucose.

Clinical Trial Registration

URL: http://clinicaltrials.gov/. Unique identifier: NCT00542503.

Cardiac adaptation in acute hypertensive pulmonary edema

The aim of this study was to evaluate the role of left ventricular (LV) dysfunction (global and regional, systolic and diastolic) acute dyssynchrony, ischemic mitral regurgitation (MR), and afterload changes in acute hypertensive pulmonary edema (AHPE). Forty-four consecutive patients were evaluated by comprehensive echocardiography during clinical and radiologic pulmonary edema (63 ± 29 minutes after first dose of treatment) and after 48 to 92 hours. Twenty age- and gender-matched asymptomatic hypertensive and diabetic subjects served as controls. AHPE was associated with increased afterload (estimated arterial elastance 3.0 vs 2.3 mm Hg/ml, p = 0.024) and subsequent decreased longitudinal LV systolic function (mean strain of 6 basal segments -11.0% vs -15.4%; p = 0.015) compared to the stable follow-up state. However, global LV systolic function was maintained (estimated ventricular elastance 1.7 vs 1.6 mm Hg/ml, stroke work 76.7 vs 84.5 cJ, ejection fraction 0.33 vs 0.37, all nonsignificant). Except for diastolic filling time (ratio to cardiac cycle 0.41 vs 0.49, p <0.001), other indexes of diastolic function, dyssynchrony, and MR severity were similar between evaluations. Patients with AHPE had worse ventricular-arterial coupling, systolic function, estimated diastolic stiffness, and filling pressures compared to asymptomatic controls, suggesting a decreased capacity to adapt to changes in loading. In conclusion, acute alterations of systolic and diastolic LV function, myocardial synchrony, and ischemic MR are unlikely mechanisms of AHPE. Rather, AHPE is likely to develop in patients with decreased systolic and diastolic capacity to adapt to acute changes in loading.

A general theory of acute and chronic heart failure

Current concepts of heart failure propose multiple heterogeneous pathophysiological mechanisms. Recently a theoretical framework for understanding chronic heart failure was suggested. This paper develops this framework to include acute heart failure syndromes. We propose that all acute heart failure syndromes may be understood in terms of a relative fall in left ventricular stroke volume. The initial compensatory mechanism is frequently a tachycardia often resulting in a near normal cardiac output. In more severe forms a fall in cardiac output causes hypotension or cardiogenic shock. In chronic heart failure the stroke volume and cardiac output is returned to normal predominantly through ventricular remodeling or dilatation. Ejection fraction is simply the ratio of stroke volume and end-diastolic volume. The resting stroke volume is predetermined by the tissue's needs; therefore, if the ejection fraction changes, the end-diastolic volume must change in a reciprocal manner. The potential role of the right heart in influencing the presentation of left heart disease is examined. We propose that acute pulmonary edema occurs when the right ventricular stroke volume exceeds left ventricular stroke volume leading to fluid accumulation in the alveoli. The possible role of the right heart in determining pulmonary hypertension and raised filling pressures in left-sided heart disease are discussed. Different clinical scenarios are presented to help clarify these proposed mechanisms and the clinical implications of these theories are discussed. Finally an alternative definition of heart failure is proposed.

Simultaneous measurement of left and right ventricular volumes and ejection fraction during dobutamine stress cardiovascular magnetic resonance

OBJECTIVE

During cardiovascular stress, if right ventricular (RV) stroke volume exceeds left ventricular (LV) stroke volume, then a large volume of blood is displaced into the pulmonary circulation that may precipitate pulmonary edema. We sought to determine the metrics by which cardiovascular magnetic resonance (CMR) could measure simultaneous displacement of RV and LV stroke volumes during dobutamine stress.

METHODS

Thirteen healthy subjects (5 women) aged 53 ± 10 years without medical conditions and taking no medications underwent 2 CMR examinations at 1.5 T separated by 4 to 8 weeks in which RV and LV stroke volumes were determined during intravenous dobutamine and atropine infused to achieve 80% of the maximum predicted heart rate response for age.

RESULTS

The RV and LV stroke volumes were highly correlated at each level of stress (rest: r = 0.98, P = 0.007; low stress: r = 0.87, P = 0.001; and peak stress: r = 0.88, P = 0.001), and the mean difference in SV at each level of stress (rest, low stress, and peak stress was 0 to 2 mL on examinations 1 and 2.

CONCLUSIONS

Simultaneous change in right and left ventricular stroke volumes can be assessed in a highly reproducible manner throughout the course of dobutamine CMR stress administered to achieve 80% of maximum predicted heart rate response for age. This technology may help identify discrepancies in RV and LV stroke volumes during cardiovascular stress that are associated with the development of pulmonary edema.