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Hemodynamic response to LV pacing predictive of need for post-CRT remodeling
Duckett S. J Am Coll Cardiol. 2011;58:1128-1136.
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Acute hemodynamic response to left ventricular pacing is useful for predicting patients who are likely to remodel after cardiac resynchronization therapy for dilated cardiomyopathy and ischemic cardiomyopathy, according to a study.
Researchers collected information for the study from patients undergoing dilated and ischemic cardiomyopathy for cardiac resynchronization therapy (CRT). Patients underwent echocardiography before CRT, implant hemodynamic evaluation during CRT, an occlusive venogram, and LV volumes were assessed before and after CRT. Optimal coronary sinus LV lead position was determined by the largest percentage rise in the maximum rate of LV pressure to dual-chamber LV pacing. Reverse remolding was determined if there was at least a 15% reduction in LV end-systolic volume, and symptomatic response was evaluated by NYHA functional class and quality-of-life questionnaire every 6 months, according to the study.
Overall, 33 patients underwent CRT; 21 undergoing dilated and 12 ischemic cardiomyopathy. “The maximum rate of LV pressure increased significantly from baseline (P<.001) with dual-chamber LV pacing or the optimal LV lead position,” researchers said.
Reverse remolding was exhibited in 56% of patients. When predicting remolding, a more than 10% improvement in maximum rate of LV pressure from baseline with dual-chamber LV pacing was more sensitive vs. echocardiographic parameters, according to the study. Reverse remolding was experienced in 61% of patients with dilated cardiomyopathy vs. 45% with ischemic cardiomyopathy.
According to the study, there was a strong relationship for acute hemodynamic response and reverse remolding for dilated cardiomyopathy (P=.01) and ischemic cardiomyopathy (P=.04). When it came to patients with dilated cardiomyopathy, reverse remolding had a statistically significant relationship between systolic dyssynchrony index (P=.004) and intraventricular ejection fraction (P=.006). Reverse remolding was only statistically significant with intraventricular ejection fraction (P=.006), when it came to patients with ischemic cardiomyopathy.
Disclosure: Dr. Duckett reports no relevant financial disclosures.
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This is a small study in which most of the patients (91%) responded with improved symptoms. Although reverse remodeling is desirable, it is not required to obtain a clinical improvement. The implication of predicting a response is that this would be a way to decide to not place a lead or device. However, since almost everyone improved by some measure, it would not be appropriate to withhold CRT on the basis of the response. It is expected that the people who respond the most by having reverse remodeling will have an initially detectable response — no surprise. Also, this did not use biventricular pacing, just dual-chamber with LV-only pacing. This makes the data more difficult to evaluate. So, in summary, this is not surprising or very helpful. However, it does reinforce that patients have improvement, even when there is no measurable reverse remodeling.
– Bruce L. Wilkoff, MD
Cardiology
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