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Electromechanical left ventricular behavior after nonsurgical septal reduction in patients with hypertrophic
M Y Henein1, C A O'Sullivan, I S Ramzy
1Royal Brompton Hospital, London, United Kingdom.
Insights
Nonsurgical septal reduction effectively reduces left ventricular outflow tract obstruction in hypertrophic obstructive cardiomyopathy (HOCM) patients. This procedure causes localized myocardial infarction, altering septal activation and improving symptoms.
Area of Science:
- Cardiology
- Interventional Cardiology
- Cardiac Electrophysiology
Background:
- Hypertrophic obstructive cardiomyopathy (HOCM) presents significant challenges for symptom management.
- Nonsurgical septal reduction offers a potential alternative to traditional treatments like dual chamber pacing and sensing (DDD) pacing and surgical myectomy.
Purpose of the Study:
- To investigate the electromechanical effects of nonsurgical septal reduction in patients with HOCM.
- To evaluate the impact of this intervention on left ventricular outflow tract (LVOT) obstruction and cardiac function.
Main Methods:
- Studied 20 symptomatic HOCM patients using echocardiography and electrocardiogram (ECG) before and after the procedure.
- Monitored changes in LVOT gradient, LVOT diameter, QRS duration, and septal wall motion.
Main Results:
- Successful septal reduction led to a 50% decrease in LVOT gradient within 24 hours and 80% at six months.
- Significant alterations in QRS duration, axis rotation, and septal excursion were observed, indicating changes in electrical activation and mechanical coordination.
- Increased LVOT diameter and evidence of localized myocardial infarction were noted post-procedure.
Conclusions:
- Nonsurgical septal reduction effectively reduces LVOT obstruction and increases LVOT diameter.
- The procedure induces consistent alterations in septal activation and myocardial coordination, potentially contributing to symptomatic improvement.
- These electromechanical changes may mimic the benefits observed with DDD pacing in HOCM patients.
Objectives:
To investigate the electromechanical consequences of nonsurgical septal reduction in a group of patients with hypertrophic obstructive cardiomyopathy (HOCM).
Background:
Patients with HOCM may benefit symptomatically from nonsurgical septal reduction as an alternative to dual chamber pacing and sensing (DDD) pacing and surgical myectomy.
Methods:
We studied 20 symptomatic patients with HOCM (12 men), mean age 52 +/- 17 years, before and after septal reduction using echocardiography and electrocardiogram (ECG).
Results:
Septal reduction with a significant rise in cardiac enzymes was successfully achieved in all patients resulting in a 50% reduction in resting left ventricular (LV) outflow tract gradient within 24 h of procedure and an 80% reduction after six months. Left ventricular outflow tract diameter increased at 24 h with a further increase six months later. QRS duration increased by 35 ms at 24 h after procedure associated with right bundle branch block (RBBB) and significant rightward axis rotation in 16 patients. R-wave amplitude in V1 fell by 7 +/- 4 mm in 15/20 patients, 13 of whom developed reduction of septal long axis excursion. Left-axis deviation appeared in three patients and septal q-wave was suppressed in 12 long-axis excursion; peak shortening and lengthening rates all fell at the septal site by 20% at 24 h. Only septal excursion returned back to baseline values at six months. Wall motion also became incoordinate so that postejection septal shortening increased by three times control values at 24 h and by four times six months later.
Conclusions:
Nonsurgical septal reduction is associated with a drop in LV outflow tract obstruction and the creation of a localized myocardial infarction (MI) increasing LV outflow tract diameter. The technique also results in a consistent alteration of septal activation and secondary incoordination. The latter could play a significant role in gradient reduction and symptomatic improvement in a manner similar to that seen with DDD pacing.