Effect of low-amplitude two-dimensional radial strain at left ventricular pacing sites on response to cardiac resynchronization therapy.

BACKGROUND: Left ventricular (LV) lead placement to areas of scar has detrimental effects on response to cardiac resynchronization therapy (CRT). Speckle-tracking radial two-dimensional strain offers assessment of the extent of regional myocardial deformation. The aim of this study was to assess the impact of LV lead placement at areas of low-amplitude strain on CRT response. METHODS: The optimal cutoff of radial strain amplitude at the LV pacing site associated with an unfavorable CRT response was determined in a derivation group (n = 65) and then tested in a second consecutive validation group (n = 75) of patients with heart failure. Patients had concordant LV leads if placed at the most delayed site, and dyssynchrony was defined as anteroseptal to posterior delay ≥ 130 msec. CRT response was defined as a ≥15% reduction in LV end-systolic volume at 6 months. RESULTS: In the derivation group, a derived cutoff for radial strain amplitude of <9.8% defined low-amplitude segments (LAS) and had a high specificity but low sensitivity for predicting LV reverse remodeling, suggesting a strong negative predictive value. In the validation group, compared with patients without LAS at the LV pacing site, in patients with LAS (n = 16), CRT response was significantly lower (62.7% vs 31.3%, P < .05). By multivariate analysis, LV lead concordance and the absence of an LAS at the LV pacing site but not dyssynchrony were significantly related to CRT response. CONCLUSION: LV lead placement over segments with two-dimensional radial strain amplitudes <9.8% is associated with poor outcomes of CRT.

Characterization of the suitability of coronary venous anatomy for targeting left ventricular lead placement in patients undergoing cardiac resynchronization therapy.

AIMS: Recent studies suggest differences in coronary venous anatomy between patients with ischaemic (I) and non-ischaemic (N) cardiomyopathy. We hypothesize that these differences may affect the potential for left ventricular (LV) lead targeting in patients undergoing cardiac resynchronization therapy. METHODS AND RESULTS: The retrograde contrast venograms were retrospectively reviewed in 133 patients (age 68 +/- 9 years, 101 males). The quantity and distribution of veins were recorded as well as the final lead position. There were no major differences in the distribution of LV lead positions between I and N [posterior vein, 14.0% (I) vs. 15.8% (N); posterolateral vein, 21.1 vs. 18.4%; lateral vein, 59.7 vs. 50.0%; anterolateral vein, 3.5 vs. 13.2%; P= NS]. Excluding the middle and great cardiac veins, in total only 59 of 133 patients had more than one suitable vein as potential targets for LV lead placement (I, 36.8% vs. N, 50.0%; P = 0.16). CONCLUSION: Underlying aetiology does not affect the quantity and distribution of coronary veins available for LV lead placement. The limitations of venous anatomy restrict LV lead placement to a single vein with little scope for site selection in almost half of all the patients. Given these limitations, in many patients, prospective targeting of LV lead placement may require a direct surgical approach.

Left ventricular lead placement in cardiac resynchronization therapy: where and how?

Cardiac resynchronization therapy (CRT) offers proven benefit to patients with refractory symptomatic chronic heart failure (New York Heart Association Class III or IV), severe left ventricular (LV) systolic dysfunction (LV ejection fraction <35%), and LV dyssynchrony (QRS width >120 ms). Cardiac resynchronization therapy has the potential to improve survival and functional capacity, reduce hospital admissions, and promote LV reverse remodelling. Although difficult to truly evaluate, up to 30% of patients do not attain symptomatic benefit. Factors associated with a poor outcome include inappropriate patient selection, inadequate device programming, presence of myocardial scar, and suboptimal LV lead placement. Left ventricular dyssynchrony is an important determinant of CRT response, although at present no reliable single measure to identify patients beyond QRS width has been identified. In this review, we discuss the effect of LV lead placement to pace the region of maximal dyssynchrony, the impact of total scar burden on response, and the relationship between LV lead position and localized scar. Consideration is also given to prospectively defining placement of the LV lead including surgical epicardial lead positioning.