Left ventricular lead proximity to an akinetic segment and impact on outcome of cardiac resynchronization therapy.

BACKGROUND: Previous studies report that the optimal pacing site for cardiac resynchronization therapy (CRT) is along the left ventricular (LV) lateral and postero-lateral (PL) wall. However, little is known regarding whether pacing over an akinetic site impacts the contractile response and long-term outcome from CRT. METHODS AND RESULTS: A total of 38 patients with ischemic cardiomyopathy were studied for their acute hemodynamic and 12-month clinical response to CRT. The intraindividual percentage change in dP/dt (%DeltadP/dt), over baseline, was derived from the mitral regurgitation (MR) Doppler profile with CRT on versus off. Two-dimensional echocardiography was used for myocardial segmentation and determinination of akinetic sites. LV lead implant site was determined using angiographic and radiographic data and categorized as being "on" (group 1) or "off" (group 2) an akinetic site. Long-term response was measured as a combined endpoint of hospitalization for heart failure and/or all cause mortality at 12 months. Time to primary endpoint was estimated by the Kaplan-Meier method. Clinical characteristics and acute hemodynamic response was similar in both (group 1 [n = 14]; %DeltadP/dt 48.8 +/- 67.4% vs group 2 [n = 24]; %DeltadP/dt 32.2 +/- 40.1%, P = 0.92). No difference in long-term outcome was observed (P = 0.59). In contrast, lead placement in PL or mid-lateral (ML) positions was associated with a better acute hemodynamic response when compared to antero-lateral (AL) positions (PL, %DeltadP/dt 45.7 +/- 50.7% and ML, %DeltadP/dt 45.1 +/- 58.8% vs AL, %DeltadP/dt 2.9 +/- 30.9%, respectively, P = 0.014). CONCLUSION: LV lead proximity to an akinetic segment does not impact acute hemodynamic or 12-month clinical response to CRT.

Usefulness of a novel "response score" to predict hemodynamic and clinical outcome from cardiac resynchronization therapy.

Cardiac resynchronization therapy (CRT) is an important treatment for patients with congestive heart failure and ventricular dyssynchrony, but response to CRT is highly variable. We assessed whether a scoring system that encompasses a combination of patient selection and procedural variables would improve prediction of CRT response. Thirty-nine patients who underwent CRT with echocardiographic assessment of baseline contractility and left ventricular (LV) dyssynchrony, intraprocedural assessment of LV lead electrical delay, and postprocedural chest radiography were included. Baseline LV dyssynchrony was measured by Doppler tissue velocity imaging as the maximum time difference between peak systolic velocity of anterior, lateral, posterior, and septal walls. The hemodynamic effect of CRT was measured by Doppler analysis of mitral regurgitation as percent change in maximal +dP/dt (DeltadP/dt) with CRT on versus off. Acute responders to CRT were defined as Deltadp/dt >or=25%. Clinical response was measured as a combined end point of hospitalization for heart failure and all-cause mortality. A 4-point response score was generated using variables associated with DeltadP/dt and assigning 1 point for a dorsoventral LV/right ventricular interlead distance>10 cm, 1 point for a LV lead electrical delay>or=50%, 1 point for a baseline maximum +dP/dt <600 mm Hg/s, and 1 point for a maximum time difference>100 ms. In conclusion, there was a significant association between response score (0 to 4 points) and acute hemodynamic response to CRT (p<0.0001). Kaplan-Meier analysis associated a higher response score with improved 12-month event-free survival after CRT implantation (p=0.0019).

Radiographic left ventricular-right ventricular interlead distance predicts the acute hemodynamic response to cardiac resynchronization therapy.

Placement of left ventricular (LV) and right ventricular (RV) leads with maximal interlead separation is frequently sought during cardiac resynchronization therapy (CRT), but few published data are available to support this. This study examined the relation between LV and RV lead separation and the acute effects of CRT on cardiac contractility. A total of 51 consecutive patients who underwent CRT for standard indications with sufficient mitral regurgitation for echocardiographic assessment of contractility (using Doppler profiles of mitral regurgitation as a percentage of change in dP/dt [DeltadP/dt] with CRT on and off), successful transvenous LV lead placement, and postprocedural chest radiography were evaluated. The separation of the LV and RV lead tips (direct interlead distance and horizontal and vertical components) was determined on postprocedural posteroanterior and lateral radiographs. The corrected direct LV-RV interlead distance on the lateral radiograph was correlated with the DeltadP/dt (n = 51, r = 0.43, p = 0.002). The lateral interlead distance in the horizontal plane (r = 0.58, p <0.0001), but not the vertical plane (r = -0.28, p = NS), correlated with the DeltadP/dt. The corrected horizontal interlead distance on the lateral film was greater in acute hemodynamic responders to CRT (DeltadP/dt >25%) compared with nonresponders (14.4 +/- 5.4 vs 9.2 +/- 5.8 cm, p = 0.002). Other LV-RV measures on the posteroanterior and lateral radiographs did not correlate with the DeltadP/dt. Use of these findings may help to guide the sites of LV and RV lead placement to maximize the benefit derived from CRT.

Cocaine-induced myocardial infarction associated with severe reversible systolic dysfunction and pulmonary edema.

Myocardial infarction (MI) associated to cocaine use was originally reported in 1982 and cases are being encountered more frequently in our milieu. The literature regarding this diagnosis has included mostly cases of cocaine associated chest pain and MI without serious sequelae. A lesser number of reports however focus on the clinical presentation of severe myocardial dysfunction and severe pulmonary edema, with the mechanism for pulmonary edema still being debated. Although previously described individually, these manifestations are thought to be an uncommon complication of cocaine ingestion. In this article the subject is reviewed and we report our experience with two patients that presented to our care with severe pulmonary edema and concomitant severe left ventricular systolic dysfunction that resolved spontaneously with supportive therapy. It is felt that this clinical picture after cocaine use may be more common than expected. In this article we discuss the possible mechanisms associated to this presentation as well as review the literature regarding this subject.

Cardiac pacemakers: an update.

In this update of cardiac pacing we review the new revised ACC/AHA/NASPE Guidelines for implantation of cardiac pacemakers, including selection of pacing mode, possible new indications, and other more recent advances in cardiac pacing.