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Early changes in left ventricular subendocardial function after successful coronary angioplasty
M Y Henein1, K Priestley, T Davarashvili
1Cardiac Department, Royal Brompton National Heart and Lung Hospital, London.
Insights
Coronary artery disease impairs resting left ventricular long axis function, affecting subendocardial fibers. Successful angioplasty improves these systolic and diastolic abnormalities, indicating they stem from coronary stenosis.
Area of Science:
- Cardiology
- Cardiac Physiology
- Medical Imaging
Background:
- Coronary artery disease (CAD) is a leading cause of morbidity and mortality.
- Left ventricular (LV) long axis function, particularly subendocardial function, is crucial for efficient cardiac output.
- The impact of coronary angioplasty on resting LV long axis function is not fully understood.
Purpose of the Study:
- To investigate the early effects of coronary angioplasty on resting left ventricular long axis function.
- To determine if abnormalities in long axis function are directly related to coronary artery stenosis.
Main Methods:
- Prospective echocardiographic and Doppler examination of 23 patients with significant coronary artery disease.
- Measurements were taken before and after single vessel coronary angioplasty.
- Analysis focused on isovolumic relaxation time, transverse dimension changes, diastolic thinning and lengthening rates, and transmitral Doppler E/A ratio.
Main Results:
- Before angioplasty, patients exhibited prolonged isovolumic relaxation time, abnormal long axis motion, delayed diastolic lengthening, and reduced early diastolic thinning rates.
- Transmitral Doppler E/A ratio was modestly reduced.
- Following successful angioplasty, isovolumic relaxation time shortened, long axis motion normalized, and early diastolic lengthening and thinning rates increased.
Conclusions:
- Resting long axis motion, reflecting subendocardial fiber function, is consistently abnormal in patients with coronary artery disease.
- Successful coronary angioplasty leads to a return towards normal of these systolic and diastolic abnormalities.
- These findings suggest that the observed functional deficits are a direct consequence of coronary artery stenosis.
Objective:
To study the early effects of coronary angioplasty on resting left ventricular long axis function, reflecting that of the subendocardium.
Design:
Prospective echocardiographic and Doppler examination of patients with coronary artery disease, before and after single vessel coronary angioplasty.
Setting:
A tertiary referral centre for cardiac diseases with facilities for invasive and non-invasive investigation.
Patients:
23 patients with significant left coronary disease being considered for coronary angioplasty.
Results:
Before angioplasty the mean (SD) isovolumic relaxation time was longer than normal (75(19) ms v 55 (10), p < 0.001) with a significant increase in transverse dimension change before mitral valve opening, and peak rate of early diastolic thinning (8(3) v 10.4 (2.6) cm/s (p < 0.001)) was reduced. Long axis motion was frequently abnormal. The interval from the onset of the Q wave to the onset of shortening was prolonged (118 (30) ms v 90 (19) at the left site and 115 (26) ms v 81 (9) at the septal site, p < 0.001) and the onset of early diastolic rapid lengthening delayed with respect to the aortic valve closure sound (A2) by 85 (34) ms v 58 (11) at the left site and 88 (33) ms v 60 (9) at the septal site (p < 0.001). Although overall amplitude was reduced at the septal site only (1.23 (0.3) cm v 1.5 (0.4), p < 0.05), the extent (0.8 (0.2) cm v 1.04 (0.3) at the left site and 0.66 (0.2) cm v 0.9 (0.3) at the septal site, p < 0.001) and peak rate (6.2 (2) cm/s v 10 (2.5) at the left site and 5.4 (2.3) cm/s v 8.5 (2) at the septal site, p < 001) of early diastolic lengthening were both much lower than normal. The E/A ratio on transmitral Doppler was modestly reduced (1.0 (0.7) v 1.4 (0.4), p < 0.05). After angioplasty: isovolumic relaxation time shortened to 64 (18) ms (p < 0.001) and left ventricular incoordination regressed. Long axis shortening with respect to Q (98 (32) ms v 118 (30) at the left site and 94 (23) ms v 115 (26) at the septal site, p < 0.01) and that of lengthening with respect to A2 both normalised. Early diastolic peak lengthening rate increased (7.5 (2.1) cm/s v 6.2 (2) at the left site, and 6.3 (2.4) cm/s v 5.4 (2.3) at the septal site, p < 0.001). The early diastolic peak thinning rate of the posterior wall significantly increased (10 (3.5) cm/s v 8 (3), p < 0.005) as did mitral E/A ratio 1.2 (0.7) v 1.0 (0.7), p < 0.05).
Conclusion:
Long axis motion, representing the function of longitudinally arranged subendocardial fibres, is consistently abnormal in the resting state in coronary artery disease. These systolic and diastolic abnormalities return towards normal after successful angioplasty, suggesting that they are the direct effect of coronary artery stenosis.