Abstract
The aim of this study was to clarify the relative contribution of elevated left ventricle (LV) filling pressure (FP) estimated by pulmonary venous (PV) and mitral flow, transesophageal Doppler recording (TEE), and other extracardiac factors like obesity and renal insufficiency (KI) to exercise capacity (ExC) evaluated by cardiopulmonary exercise testing (CPX) in patients with dilated cardiomyopathy (DCM). During the CPX test, 119 patients (pts) with DCM underwent both peak VO2 consumption and then TEE with color-guided pulsed-wave Doppler recording of PVF and transmitral flow. In 78 patients (65%), peak VO2 was normal or mildly reduced (>14 mL/kg/min) (group 1) while it was markedly reduced (≤14 mL/kg/min) in 41 (group 2). In univariate analysis, systolic fraction (S Fract), a predictor of elevated pre-a LV diastolic FP, appeared to be the best diastolic parameter predicting a significantly reduced peak VO2. Logistic regression analysis identified five parameters yielding a unique, statistically significant contribution in predicting reduced ExC: creatinine clearance < 52 mL/min (odds ratio (OR) = 7.4, p = 0.007); female gender (OR = 7.1, p = 0.004); BMI > 28 (OR = 5.8, p = 0.029), age > 62 years (OR = 5.5, p = 0.03), S Fract < 59% (OR = 4.9, p = 0.02). Conclusion: KI was the strongest predictor of reduced ExC. The other modifiable factors were obesity and severe LV diastolic dysfunction expressed by blunted systolic venous flow. Contrarily, LV ejection fraction was not predictive, confirming other previous studies. This has important clinical implications.
Highlights
Dilated cardiomyopathies (DCM) are an escalating problem in the modern medicine, aggravated by the still poor knowledge of the underlying etiology and associated with poor prognosis and disabling symptoms like dyspnea and reduced functional capacity [1].Generally, a limitation in performing an aerobic effort is attributed to poor left ventricular contractile function
The prediction of the left ventricular filling pressure best attained with the combination of transmitral and pulmonary venous flow Doppler recording identified 62 (51%) patients with normal left ventricular filling pressure, 20 (16%) with isolated increase in Left ventricular (LV) filling pressure after atrial contraction with presumably normal mean atrial pressure, and 40 (33%) with elevation of the left ventricular pressure before atrial contraction (Pre-a increase of pressure) (Table 2)
This study has clearly shown for the first time that elevated LV filling pressure as assessed by pulmonary flow velocity Doppler recording, rather than LV EF, can significantly explain a reduced functional capacity as objectively measured by cardiopulmonary exercise testing (CPX)
Summary
Dilated cardiomyopathies (DCM) are an escalating problem in the modern medicine, aggravated by the still poor knowledge of the underlying etiology and associated with poor prognosis and disabling symptoms like dyspnea and reduced functional capacity [1].Generally, a limitation in performing an aerobic effort is attributed to poor left ventricular contractile function. What specific resting cardiac abnormalities mediate the poor exercise performance is not clearly understood. The physiology of restricted LV filling raises LV filling pressure to elevated values, transmitted back to the left atrium and the pulmonary capillary. This hemodynamic derangement increases the net filtration pressure, imbibing the pulmonary parenchyma and reducing pulmonary oxygen diffusion [3,4].
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