|Year : 2008 | Volume
| Issue : 3 | Page : 104-108
Short Term Effect of Cardiac Resynchronization Therapy on Functional Recovery of Patients with Congestive Heart Failure
Zaky Hosam, Habibi Hamid, Abdel Aziz Mohamed, Aljassim Obaid
Dubai Heart Centre, Dubai Hospital, Dubai, United Arab Emirates
|Date of Web Publication||17-Jun-2010|
P.O. Box 21910, Dubai
United Arab Emirates
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Objectives: We investigated the impact of six month cardiac resynchronization therapy (CRT) on echocardiographic and clinical variables in congestive heart failure patients (CHF).
Background: Cardiac resynchronization reduces symptoms and improves left ventricular function in many patients with heart failure due to left ventricular systolic dysfunction and cardiac dyssynchrony1. We evaluated its short term effects on reverse remodeling of the left ventricle and on the patient symptoms.
Methods: The evaluated group contains seven patients (1 woman and 6 men). The average age was 62.43 ± 21.9 years. All the patients had CHF with prolonged QRS. The etiology was ischemic in 5 and idiopathic in 2. All patients underwent physical examination and six minutes hall walk test. Echocardiography was done to evaluate basic cardiac function, left ventricular ejection fraction (LVEF, M-mode & Simpson), left ventricular end diastolic diameter (LVEDD), left ventricular end systolic diameter (LVESD), MR severity and dysynchrony by Doppler and tissue Doppler. Results were compared before implantation and six weeks and six month after CRT implantation.
Results: LVEDD and LVESD were reduced after six months, LVEDD was reduced from 75.9 ± 7.4 to 71.0 ± 4.1 mm ± SD (p value 0.04) and LVESD was reduced from 62.4 ± 8.5 to 59.3 ± 7.0 (p value 0.15). Ejection fraction was significantly increased after 6 weeks from 25 ± 7.1% to 31 ± 4.5%, (p value 0.03).The average grade of mitral regurgitation has increased from 1.67 ± 0.82 at baseline to 1.75 ± 0.88 at 6 month follow up, (p value 0.66) by semi-quantitative analysis.
Conclusion: Although the study was performed on a small number of patients, yet we are convinced that Cardiac resynchronization therapy had favorable hemodynamic and clinical results in our heart failure patients.
Keywords: cardiac resynchronization therapy, congestive heart failure, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, mitral regurgitation, LVEF
|How to cite this article:|
Hosam Z, Hamid H, Mohamed AA, Obaid A. Short Term Effect of Cardiac Resynchronization Therapy on Functional Recovery of Patients with Congestive Heart Failure. Heart Views 2008;9:104-8
|How to cite this URL:|
Hosam Z, Hamid H, Mohamed AA, Obaid A. Short Term Effect of Cardiac Resynchronization Therapy on Functional Recovery of Patients with Congestive Heart Failure. Heart Views [serial online] 2008 [cited 2019 Dec 9];9:104-8. Available from: http://www.heartviews.org/text.asp?2008/9/3/104/63753
| Introduction|| |
Over the past decade, investigators have established that ventricular stimulation of right and left ventricle together (biventricular), or just left ventricular free wall itself, can improve the mechanics and energetics of the failing heart with discoordinate contraction. Cardiac resynchronization therapy (CRT) have gained an established role in the treatment of patients with advanced heart failure due to systolic dysfunction in association with QRS delay .Patients not only feel better and can do more with CRT, but also they live longer and are hospitalized less ,, .
| Methods|| |
Our study included 7 patients. All patients gave written informed consent for the procedure and the study. In this study, we had studied the effect of CRT on our patients regarding symptoms, 6 minutes hall walk test and echocardiographic measures of reverse remodeling at 6 weeks and 6 month intervals. The design, inclusion and exclusion criteria of the study are as follows:
| Inclusion criteria|| |
- Patients with CHF of both ischemic and nonischemic origin.
- NYHA functional class III or IV.
- On optimal medical therapy
- LVEF ≤ 0.35
- LVEDD ≥ 5.5 cm
- QRS duration ≥ 120 msec.
- Echocardiographic evidence of intra and inter-ventricular conduction delay.
| Exclusion criteria|| |
- Asymptomatic heart failure patients
- Reversible risk factors like ischemia or operable valve lesion.
| Patient's evaluation before the procedure|| |
- History taking to assess the NYHA functional class, to ensure that the patient is on maximal medical therapy and complies well with medication and absence of treatable causes for the heart failure.
- Examining the chest, heart and abdomen for signs of heart failure and underlying etiology.
- 6 minutes hall walk test for ambulant patients.
- ECG: for PR interval and QRS width.
- CXR: for cardiac silhouette and lung field evaluation.
| A. Echocardiographic measurements|| |
Transthoracic echocardiography was performed shortly before pacemaker implantation and then after six weeks and six months when patients were paced with the optimal mode and settings. Left atrial and left ventricular diameters were determined using M-mode echocardiography under two-dimensional guidance in the parasternal long-axis view according to the recommendation of chamber quantification by the American society of echocardiography 2006. The end of diastole was defined by the largest diameter while the end of systole was defined by the smallest cavity area before mitral valve opening. Biplane left ventricular end systolic volume (LVESV) and left ventricular end diastolic volume (LVEDV) were respectively calculated from the two-chamber and four-chamber views, according to the modified Simpson's rule. Measurements were averaged from three cardiac cycles. Left ventricular EF was calculated as: (LVEDV - LVESV)/ LVEDV x1005. Mitral regurgitation (MR) was semiquantitatively graded on a 4-point scale (grades 0 to 3) using color-coded Doppler signals, the maximal jet area was measured in the parasternal and apical views4. Final analysis was performed off-line (from videotape) by two independent observers after manual recalibration on a Phillips sonos 7500 ultrasound scanner.
| B. Evidence of dysynchrony|| |
Aortic (AO) pre-ejection time ≥ 140 msec from onset of QRS to start of aortic ejection was calculated to diagnose intraventricular conduction delay  . Measuring pulmonary pre-ejection time and confirming interventricular conduction delay by a difference between AO pre ejection and pulmonary pre ejection of more than 40 msec was done  . Tissue Doppler evidence of desynchrony in the form delayed longitudinal contraction by ≥ 70 msec between the basal septum and the basal lateral wall in the 4 chamber view and evidence of post systolic motion was also done  .
| Pacing protocol and Operative procedure|| |
The implantation of atrio-biventricular pacemakers was done through creation of a pocket in the delto-pectoral groove. Pacing leads were inserted in the right atrial appendage, right ventricular apex and coronary sinus. For LV pacing, we tried to reach mid lateral wall position. Cases which had ICD implantation, defibrillation threshold testing twice at 10 joules less than the maximumal output of the device was done. All leads were tested for threshold of pacing, impedance, and RA and RV leads for P wave and R wave sensing. Testing for pherenic nerve stimulation at 10 volts was done for all leads.
One case with persistent left superior vena cava with no apparent tributary had epicardial lead implantation through minimal thoracotomy by the cardiac surgeon. Postoperative programming for the atrioventricular (A-V) delay and ventriculo-ventricular (V-V) delay using echocardiography for optimization. ICD cases were programmed on the VF zone where indicated for primary prevention of sudden cardiac death.
Follow up: The Following steps were repeated in 6 weeks and 6 month follow-up:
- History taking, examination and 6 minutes hall walk test.
- Echocardiography measurements of LVEDD, LVESD, LVEF, and mitral regurgitation (MR).
- Doppler examination for mitral inflow to optimize the A-V delay and for left ventricular out flow tract (LVOT) to optimize the V- V delay.
- The pacemakers have been interrogated and tested for threshold, impedance, and sensitivity of all leads and percent pacing.
- ICD cases were interrogated for possible shocks or any attack of dysrrhythmia.
| Concomitant drug treatment|| |
For patients to be included in the study, they had to be in a stable NYHA functional class III without a change in medication or in class IV without the need for intravenous inotropic drugs during the last month.
| Statistical analysis|| |
Statistical analysis was performed using SPSS 13 software (statistical Package for Social Science) for windows. Results were expressed as mean ± SD or mean (range) as appropriate using Student's t-test & Wilcoxon test wherever applicable. A p-value of less than 0.05 (two - tailed) was considered statistically significant.
| Results|| |
In this study, 7 patients were recruited and one of them was a female. The mean age was 62.43 years ± 21.9 years. Five patients had ischemic cardiomyopathy and 2 had nonischemic cardiomyopathy. One of them had persistent left superior vena cava with no tributary. In this case Left ventricular epicardial lead was implanted by mini-thoracotomy by the cardiac surgeon, however unfortunately during the follow up, we found that he developed exit block with the highest output of the Frontier Saint Jude pacemaker of 7.5 volts and pulse width of 1.5 msec, no LV capture was detected and was considered a non-responder.
One out of 7 patients had 45% CRT delivered most of the time due to frequent PVCs, three had 92% CRT delivery and three had 100% CRT delivery all the time.
Patient's mean ± (SD) NYHA functional class was 3.14 ± (0.38) at baseline and dropped to a mean of 2.14 ± (0.38) at 6 weeks (P value 0.02) and remained steady upto 6 months .There were statistically significant changes denoting sustained benefit attained at 6 weeks [Table 1] .
The 6 minutes hall walk test has increased in 6 weeks and 6 months follow up. However when analyzed using paired t test, it revealed no statistically significant change between the baselines and both the 6 weeks and the 6 months follow up. This could be explained by the small number of cases recruited in the study.
Although the changes in the 6 minutes walk test was statistically insignificant, the distance walked at the 6 weeks increased in comparison to the baseline and increased further at the 6 months follow up [Figure 1] and [Figure 2].
Mitral incompetence did not show significant change when the baseline was compared to the 6 weeks and the 6 months follow up.
The end diastolic diameter at baseline versus 6 weeks showed near significant change (p value 0.6); and baseline versus 6 months follow up, the end diastolic diameter showed statistically significant reduction using paired t-test. The end systolic diameter decreased when comparing the baseline follow up to 6 weeks and 6 months, the change was not significant statistically [Table 1].
When the ejection fraction was compared at baseline to 6 weeks, the increase in EF was significant; and to 6 months follows up, there was an increase in the Ejection fraction but the change was statistically insignificant. We can conclude that the benefit in 6 weeks was sustained at 6 months.
| Discussion|| |
In this study, most of the changes in the parameters measured go in line with the major randomized trials. Some of the results were statistically insignificant mostly due to the small number recruited.
The mean NYHA functional class improved significantly when comparing the baseline data to 6 weeks data and also improved significantly when comparing the baseline to 6 months follow up which goes in agreement with most of the short term randomized trials ,,,, .
In our study, the 6 minutes hall walk test distance has increased in both the 6 weeks and the 6 months follow up, but was not statistically significant; in comparison to other trials where the increase in the distance walked was significant ,,,, . We believe that the small number of cases is the reason behind the non significant result.
The functional mitral incompetence did not change significantly in our cohort although others , documented the significant decrease in functional mitral incompetence for the patients receiving CRT.
The ejection fraction showed significant improvement in baseline versus 6 weeks and nonsignificant increase in the baseline versus 6 months. That increase was also observed in other trials , where the ejection fraction increased significantly at 6 months follow up.
The end diastolic diameter decreased significantly in 6 months follow up and near significantly (p value 0.6) in 6 weeks follows up. Also other investigators ,,, showed statistically significant decrease in the end diastolic diameter.
The end systolic diameter in this study decreased nonsignificantly both in the 6 weeks and 6 months follow up, although by stllebrink and colleagues14 as well as others ,,, decreased significantly in the 6 months follow up.
| Conclusion|| |
Cardiac resynchronization therapy on short term follow up evaluation proved beneficial on the patients' symptoms, exercise capacity and evidence of inducing LV reverse remodeling by echocardiography.
| Study Limitation|| |
The major limitation of this study was the small number of patients recruited that could explain why some of the results were not statistically significant.
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[Figure 1], [Figure 2]