SWMA tied to subsequent cardiac events, altered left ventricular morphology in IDCM
Patients with idiopathic dilated cardiomyopathy (IDCM) commonly have left ventricular (LV) segmented wall motion abnormalities (SWMA), a new study has shown.
Moreover, SWMA is tied independently to impaired functional and morphometric LV improvement following optimal pharmacotherapy (OPT), and poor overall prognosis.
“In this study, we found [that] the event-free survival rate was worse in the patients with SWMA than in those without SWMA and [that] among the clinical parameters at baseline, SWMA was one of the independent predictors for the cardiac events as well as decreased LV end-systolic dimension index (LVESDI) after the establishment of OPT,” said researchers.
In the study cohort of 85 IDCM patients (mean age 55±13 years; 80 percent male), those who had SWMA (SWMA+; n=26) had significantly lower rates of cardiac event-free survival compared with those who had diffuse LV hypokinesis (SWMA-; n=59; p<0.001), according to the Kaplan-Meier survival curve. [Int Heart J 2017;58:544-550]
Subsequent multivariate analysis revealed that New York Heart Association (NYHA) functional class of III to IV (hazard ratio [HR], 9.20; 95 percent CI, 1.65 to 47.4; p=0.01) and SWMA+ (HR, 3.38; 1.11 to 10.8; p=0.03) were significant clinical predictors of cardiac events.
Echocardiography showed that SWMA- patients had significantly greater reductions in LVESDI (8±6 vs 3±6 mm/m2; p=0.001) and increases in LV ejection fraction (LVEF; p<0.05) compared with SWMA+ patients.
SWMA+ (p=0.02), late gadolinium enhancement (p=0.01) and serum sodium (p=0.02) were independent predictors of decreased LVESDI 12 months after OPT.
While the exact mechanism by which SWMA exerts its clinical impact on IDCM patients is still unknown, several studies have proposed possibilities, according to researchers.
“Among them are a partial-volume effect caused by reduced wall thickening, down-regulated perfusion secondary to a reduced oxygen demand, increased intramyocardial pressure during diastole, and fibrotic alterations,” they enumerated. [Arch Intern Med 1992;152:769-772; Heart Rhythm 2010;1:1390-1395]
“Another study estimated SWMA using nuclear techniques showing that patients with regional abnormalities or focal defects exhibited more advanced [heart failure] and had a poor prognosis, possibly derived from ventricular arrhythmia by regional myocardial sympathetic denervation,” they added. [J Nucl Cardiol 2002;9;15-22]
IDCM patients with LVEF <45 percent at baseline were recruited from the Kitasato University Hospital. Exclusion criteria included left bundle branch block, ventricular pacemaker implants, coronary artery diseases and secondary causes of cardiomyopathy.
All participants underwent electrocardiography and echocardiography at baseline and at 12 months. Left ventriculography (LVG) was performed to evaluate LV wall motion.
“The findings of this study have important clinical implications for the management of newly-diagnosed IDCM patients,” researchers claimed. “Nonpharmacological device treatment including [implantable cardiovascular defibrillator] and [cardiac resynchronization therapy] showed clinical benefits in selected patients with reduced LVEF.”
“Based on the present study, the recommended therapeutic option for patients without SWMA by conventional LVG would be to pursue pharmacotherapies in anticipation of subsequent LV reverse remodeling. Alternatively, in patients with SWMA, earlier adaptability of nonpharmacotherapies or other heart-substitutional treatments may be preferable therapeutic options,” they continued.