Raveen Bazaz

A prospective pilot study to evaluate the relationship between acute change in left ventricular synchrony after cardiac resynchronization therapy and patient outcome using a single-injection gated SPECT protocol.

Background— There are ongoing efforts to optimize patient selection criteria for cardiac resynchronization therapy (CRT). In this regard, the relationship between acute change in left ventricular synchrony (LV) after CRT and patient outcome remains undefined. Methods and Results— A novel protocol was designed to evaluate acute change in left LV synchrony after CRT using phase analysis of standard gated single-photon emission computed tomography (SPECT) myocardial perfusion imaging with a single injection of radiotracer and prospectively applied to 44 patients undergoing CRT. Immediately after CRT, 18 (41%), 11 (25%), and 15 (34%) patients had an improvement, no change, or a worsening in LV synchrony. An algorithm incorporating the presence of baseline dyssynchrony, myocardial scar burden, and lead concordance predicted acute improvement or no change in LV synchrony with 72% sensitivity, 93% specificity, 96% positive predictive value, and 64% negative predictive value and had 96% negative predictive value for acute deterioration in synchrony. Over a follow-up period of 9.6±6.8 months, patients who had an acute deterioration in synchrony after CRT had a higher composite event rate of death, heart failure hospitalizations, appropriate defibrillator discharges, and CRT device deactivation for worsening heart failure symptoms, compared with patients who had an improvement or no change [hazard ratio, 4.6 (1.3 to 16.0); log rank test; P=0.003]. Conclusions— In this single-center pilot study, phase analysis of gated SPECT was successfully used to predict acute change in LV synchrony and patient outcome after CRT.

Independent multicenter study of Riata and Riata ST implantable cardioverter-defibrillator leads.

BACKGROUND Riata and Riata ST leads (St Jude Medical, Sylmar, CA) are prone to failure. There are no independent multicenter reports regarding Riata or Riata ST lead performance. OBJECTIVE To conduct a retrospective multicenter study of Riata and Riata ST leads that were implanted and followed at 7 centers. METHODS The study included adults who received St Jude Medical Riata or Riata ST leads. Data for Quattro Secure leads were obtained from an earlier study. RESULTS From 2002 to 2010, 1081 patients received a Riata (n = 774) or Riata ST (n = 307) lead. Follow-up was longer for Riata than Riata ST leads (4.2 ± 2.4 years vs 3.3 ± 1.7 years; P<.0001). During the study, 67 leads failed (6.2%), including 62 of 774 Riata (8.0%) and 5 of 307 Riata ST (1.6%) leads. Forty-seven of 67 lead failures (70.1%) were caused by electrical malfunction, and 20 lead failures (29.9%) were due to externalized conductors (ECs) that were electrically intact. Of 110 leads examined fluoroscopically, ECs were found in 26 of 81 Riata (32%) and 1 of 29 Riata ST (3.4%) leads. Of 26 Riata leads with ECs, 7 (27%) were malfunctioning. Riata leads had lower overall and malfunction free survival compared to Quattro leads (P<.0001), while Riata ST lead survival was not different (P = .422). CONCLUSIONS The survival of Riata (but not Riata ST) leads was lower than Quattro leads; however, Riata ST leads had significantly shorter follow-up than Riata leads. ECs were common in Riata leads, and more than a quarter of Riata leads that had ECs were malfunctioning. Our observations suggest that systematic fluoroscopic examination of patients with Riata leads is appropriate.

Contemporary insights into the functional anatomy of the mitral valve

The mitral valve is a highly complex structure the normal functioning of which requires the coordinated interaction of the leaflets, annulus, chordae tendineae, and papillary muscles. Perturbations of any of these components can interfere with normal valve function. The integrity of the mitral valve is also essential to maintaining normal left ventricular geometry and function through closely coupled ventricular-valvular interactions. This review summarizes recent developments in our understanding of the anatomy and physiology of the mitral valve.

Fluoroscopic Screening of Asymptomatic Patients Implanted With the Recalled Riata Lead Family

Background— The Food and Drug Administration recently issued a class I recall of the St. Jude Medical Riata implantable cardioverter-defibrillator lead presumably because of increased risk of electric failure and mechanical separation via inside-out abrasion. We sought to examine the incidence and time dependence of inside-out abrasion in asymptomatic patients implanted with the Riata lead. Methods and Results— Asymptomatic patients implanted with the Riata lead at our institution were offered voluntary fluoroscopic screening in 3 views. Electric testing of the Riata lead with provocative isometric muscle contraction was performed at the time of fluoroscopic screening. Of the 245 patients undergoing fluoroscopic screening, 53 (21.6%) patients showed clear evidence of lead separation. Of these externalized leads, 0%, 13%, and 26% had a dwell time of <3 years, 3 to 5 years, and >5 years, respectively (P=0.037). Externalized leads had a significantly pronounced decrease in R-wave amplitude (−1.7±2.9 mV versus +0.35±2.5 mV; P<0.001), and more patients with externalized leads had ≥25% decrease in R-wave amplitude from baseline (28.0% versus 8.1%; P=0.018). One patient with externalization exhibited new noise on near-field electrogram. Conclusions— The Riata lead exhibits time-dependent high rates of cable externalization exceeding 20% at >5 years of dwell time. Externalized leads are associated with a more pronounced decrease in R-wave amplitude, which may be an early marker of future electric failure. The use of fluoroscopic and electric screening of asymptomatic patients with the Riata lead remains controversial in the management of patients affected by the recent Food and Drug Administration recall.

An Abnormal Right Ventricular Apical Angle is Indicative of Global Right Ventricular Impairment

The presence of right ventricular (RV) dysfunction is an adverse prognostic indicator but current echocardiographic methods have some limitations. RV apical angles in systole and diastole were correlated with known parameters of RV function in patients without pulmonary hypertension (Group 1) and in patients with pulmonary hypertension (Group 2). RV apical angles were significantly smaller in both systole (22 ± 7°) and diastole (33 ± 6°) in Group 1 patients when compared to Group 2 (54 ± 18°, p < 0.0001 and 59 ± 17°, p < 0.0001, respectively). RV apical angles, both in systole and diastole, were strongly correlated with RV end‐systolic area (R = 0.89, p < 0.0001) and end‐diastolic area (R = 0.81, p < 0.0001), respectively. Similarly, the apical systolic and diastolic angle correlated well with decreased tricuspid annular plane systolic excursion (TAPSE, R =−0.76 and R =−0.73, p < 0.001) as well as with decreased RV fractional area change (R =−0.81 and R =−0.77, p < 0.001). Therefore, we conclude that this new measurement of RV apical angle is simple and useful to quantify RV apical structural and functional abnormalities that are well correlated with global RV impairment in patients with chronic pulmonary hypertension.

Evidence of robust coupling of atrioventricular mechanical function of the right side of the heart: insights from M-mode analysis of annular motion.

Background: Extensive data exist regarding annular descent and ventricular function. We have already demonstrated significant differences in amplitude and timing of events between maximal mitral (MAPSE) and tricuspid (TAPSE) annular plane systolic excursion as well as described quantitative temporal differences in annular ascent (AA) between the right and left sides of the heart. However, whether any relationship exists between annular ascent and descent components remains uninvestigated. Methods: Left ventricular ejection fraction (LVEF), right ventricular fractional area change (RVFAC), MAPSE, TAPSE, MV, and TV AA as well as pulsed tissue Doppler of the lateral MV and TV annuli were recorded from 53 patients. Results: In this population (age 55 ± 17 years) mean LVEF was 55 ± 19%, mean RVFAC was 47 ± 20%, mean MAPSE was 2.11 ± 0.72 cm, mean TAPSE was 1.48 ± 0.44 cm, mean MV AA was 0.52 ± 0.17 cm, TV AA was 0.96 ± 0.47, MV A‐wave 0.10 ± 0.04 cm/s, and TV A‐wave was 0.13 ± 0.05 cm/s. A more robust correlation was seen between TV AA and RVFAC than between MV AA and LVEF and also between TV AA and pulsed TDI TV A‐wave velocity than between MV AA and pulsed TDI MV A‐wave. Conclusion: Our data reveal that mechanical systolic functions of the atria and the ventricles are more closely coupled on the right than on the left side of the heart. Whether this is a result of anatomic linking or chamber geometry will require further study.

Abnormal Right Ventricular Myocardial Strain Generation in Mild Pulmonary Hypertension

Background: Although right ventricular (RV) dyssynchrony has been identified in patients with severe pulmonary hypertension due to significant RV enlargement and compromise in systolic function, a more clinically relevant question pertains to RV mechanical properties in patients with mild elevation in pulmonary artery systolic pressures (PASP). Methods: Several echocardiographic parameters and peak longitudinal strain were measured in 40 patients and divided into two groups of 20 patients based on their PASP. Results: Group I included 20 individuals (mean age 48 ± 16 years with a mean PASP of 27 ± 5 mmHg) and Group II included 20 patients (mean age 63 ± 14 years with a mean PASP of 49 ± 7 mmHg.) All time intervals were adjusted for heart rate. RV fractional area change and tricuspid annular plane systolic excursion for Group I (62 ± 12% and 2.74 ± 0.56 cm) and Group II (49 ± 14%; P < 0.02 and 2.09 ± 0.40; P < 0.002) were both normal. However, Group II had lower peak longitudinal RV free wall (RVF) strain (−27.3 ± 7.1 % vs. −31.9 ± 8.7%, P < 0.04), longer time to peak RVF strain (448 ± 57 ms vs. 411 ± 43 ms; P < 0.03) and evidence of significant RV dyssynchrony (−83 ± 55 ms vs. 1 ± 17 ms, P < 0.00001) in contrast to Group I. Conclusion: In conclusion, mild elevations in PASP affect the mechanical properties of the RV and result in RV dyssynchrony despite absence of gross abnormalities in RV size or function.

Comparative echocardiographic analysis of mitral and tricuspid annular motion: differences explained with proposed anatomic-structural correlates.

Background: Annular motion (AM) has been shown to occur during all dynamic phases of the cardiac cycle; but little is known regarding comparisons between mitral and tricuspid AM. We elected to use M‐mode to examine the extent and timing of mitral and tricuspid AM events. Methods: A complete echocardiogram was obtained in 50 patients [mean age 53 ± 16 years, mean left ventricular ejection fraction (LVEF) 57 ± 19%, and mean right ventricular fractional area change (RVFAC) of 49 ± 20%]. Timing of all AM intervals was corrected for heart rate. Results: A strong linear correlation was noted for both LVEF and maximal mitral annular systolic excursion and for RVFAC and maximal tricuspid annular systolic excursion (r = 0.91, P < 0.0001). The amplitude of both maximal mitral annular descent (1.54 ± 0.45 cm) and ascent (0.64 ± 0.23 cm) was significantly smaller than for the tricuspid annulus (2.26 ± 0.73 and 0.98 ± 0.37 cm; P < 0.0001, respectively). Furthermore, while it takes longer for the mitral than for the tricuspid annulus (403 ± 52 ms vs 308 ± 50 ms; P < 0.0001, respectively) to descend to its lowest point; the duration to reach maximal ascent is shorter for the mitral than for tricuspid annulus (90 ± 22 ms vs 115 ± 19 ms; p < 0.0001, respectively). Conclusion: Significant differences exist in both amplitude and timing of AM events between the mitral and tricuspid annuli, likely reflecting intrinsic anatomical and electromechanical differences between both sides of the heart that require further investigation.

Complications of replacing implantable devices in response to advisories: A single center experience

BACKGROUND Advisories for implanted devices present a challenging management problem since no specific guidelines exist for device replacement under these circumstances. Since the rate and severity of complications is an important factor in the decision-making, we sought to review our experience with replacement of devices under advisory. METHODS Medical records of patients with devices under advisory were reviewed. A total of 237 patients (age 68+/-13 years, men 71%, implantable cardioverter-defibrillator (ICD) 87%) underwent device replacement in response to advisories (Medtronic Inc. 43% and Guidant Inc. 57%) at our institution between February 2005 and June 2006. RESULTS The mean time from original device implantation to replacement was 31+/-16 months (3-73 months). During a mean follow-up of 198+/-103 days, there was a 5.5% overall rate of complications related to the procedure. Major complications requiring re-operation affected 2.1% of patients. There were no deaths associated with device replacement. Device failure prior to replacement was documented in 1.7% of patients, with syncope occurring in one patient. A history of diabetes mellitus (23%), peripheral vascular disease (4%), obstructive lung disease (7%), end-stage renal disease (2%), or use of anticoagulation (44%) did not predict the occurrence of complications after advisory device replacement. CONCLUSION This single center experience shows a lower major complication rate from replacement of devices under advisory than previously reported. Experience from this center and others may be useful in guiding future management of patients in the setting of device advisories.

Impact of catheter ablation on pulmonary vein morphology and mechanical function.

Introduction: Previous reports have documented that radiofrequency catheter ablation of pulmonary veins induces a significant increase in the peak velocity of transvenous blood flow. Although the magnitude of the increase infers a state of pulmonary vein stenosis, there have been no reports of direct visualization of the ablation zone.