Hypertrophic Cardiomyopathy: Analysis of Septal Thickness with Gradient Reduction in Patients Undergoing Radiofrequency Septal Ablation

Vilela, Andrea de Andrade; Shinzato, Mariane Higa; Valdigem, Bruno Pereira; Paladino, Antonio Tito; Correia, Edileide de Barros; Assef, Jorge Eduardo

doi:10.36660/abcimg.20240097i

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Original Article • Arq Bras Cardiol: Imagem cardiovasc. 38 (2) • 2025 • https://doi.org/10.36660/abcimg.20240097i linkcopy

Hypertrophic Cardiomyopathy: Analysis of Septal Thickness with Gradient Reduction in Patients Undergoing Radiofrequency Septal Ablation

Authorship SCIMAGO INSTITUTIONS RANKINGS

Background: Hypertrophic obstructive cardiomyopathy (HOCM) is an autosomal dominant genetic disorder. Invasive treatment for intraventricular gradient reduction is indicated in patients (p) who are refractory to clinical treatment with gradient ≥ 50 mmHg. Radiofrequency ablation (RFA) is one of the current options for invasive management.

Objectives: To evaluate the correlation between interventricular septal diameter and procedural success, defined as immediate post-procedural gradient reduction, improvement in functional class (FC), and sustained gradient reduction at 6-month follow-up.

Methods: Twenty-two patients with HOCM were included. Transthoracic echocardiography was performed before and six months after RFA, while transesophageal echocardiography (TEE) was carried out intraprocedure.

Results: The mean age was 56.64 years (± 12.23), with 68.18% of patients being female and 73% hypertensive. An immediate gradient reduction greater than 50% was observed in 72.7% of patients. At the 6-month follow-up, 60% of patients showed a ≥ 50% gradient reduction along with an improvement in FC. A median septal thickness of 18 mm was associated with greater procedural success compared to a median of 15 mm, and no significant change in septal thickness was observed over the 6-month follow-up period.

Conclusion: Radiofrequency septal ablation (RFSA) is an effective and safe technique for the invasive management of HOCM. The procedure enables a significant reduction in the intraventricular gradient, accompanied by improved FC and sustained short-term results. Thicker septal were associated with greater intraprocedural gradient reductions; however, there was no reduction in thickness during the 6-month follow-up.

Keywords:
Hypertrophic Cardiomyopathy; Radiofrequency Ablation

Central Illustration:
Hypertrophic Cardiomyopathy: Analysis of Septal Thickness with Gradient Reduction in Patients Undergoing Radiofrequency Septal Ablation

Clinical Characteristics	Total patients (n = 22)
Age (years) – mean (SD)	56.73 ± 12.20
Female – n (%)	15 (68%)
Male – n (%)	7 (32%)
BMI (kg/m²) – mean (SD)	29.69 ± 5.46
Body surface area (m²) – mean (SD)	1.84 ± 0.23
Smoking - n (%)	2 (9%)
Former smoker – n (%)	2 (9%)
Systemic arterial hypertension	16 (73%)
Dyslipidemia	11 (50%)
Coronary artery disease	3 (14%)
Hypothyroidism	3 (14%)
Diabetes mellitus	6 (27%)
Familial HCM	5 (23%)

Symptoms		Total patients (n = 22)
Dyspnea		22 (100%)
	FC I	0
	FC II	2 (9%)
	FC III	15 (68%)
	FC IV	5 (23%)
Angina		12 (55%)
Palpitation		6 (27%)
Syncope		7 (32%)
Fainting		5 (23%)

Medication		Total patients (n = 22)
Beta blocker		22 (100%)
	Propranolol	6 (27.3%)
	Atenolol	11 (50%)
	Metoprolol	5 (22.7%)
Amiodarone		1 (4.6%)
Disopyramide		1 (4.6%)
Calcium channel blocker		7 (31.8%)
	Amlodipine	1 (4.6%)
	Verapamil	3 (13.6%)
	Diltiazem	3 (13.6%)
ARB		4 (19.2%)
	Losartan	4 (19.2%)
Diuretics		15 (68.2%)
	Furosemide	2 (9.1%)
	Hydrochlorothiazide	4 (18.2%)
	Chlorthalidone	8 (36.4%)
	Spironolactone	13 (59.1%)

Patient	Sex	Age	Aortic Root (mm)	LA (mm)	iLA (mm/m²)	LVDD (mm)	Pre-Ablation Septal Thickness (mm)	Posterior Wall (mm)	Septum/PW Ratio	LV mass (g)	Indexed LV mass (g/m²)	EF (%)
1	M	55	33	50	60.00	44	23	11	2.09	408	178.3	69
2	F	50	32	57	81.00	47	24	12	2.00	345	156	78
3	F	51	32	40	73.00	36	15	11	1.36	201	99	74
4	F	64	29	41	37.00	41	15	10	1.50	229	165	68
5	F	71	32	47	43.00	43	18	13	1.38	341	165	70
6	F	62	30	33	46.00	42	27	19	1.42	427	207	74
7	F	58	29	52	108.00	36	18	14	1.29	214	143	70
8	M	51	36	43	36.00	44	18	12	1.50	335	163	66
9	F	23	29	39	50.00	36	17	8	2.13	189	114	67
10	F	73	34	42	49.00	48	16	13	1.23	362	189	62
11	F	64	29	46	52.00	42	15	11	1.36	252	155	65
12	M	55	35	41	37.00	51	20	11	1.82	438	223	69
13	F	79	34	56	64.00	38	21	18	1.17	367	209	69
14	F	50	36	33	40.00	40	16	14	1.14	292	200	68
15	F	54	31	38	53.00	42	15	10	1.5	237	145	66
16	M	38	33	58	43.00	49	22	13	1.69	497	225	61
17	M	51	36	46	46.00	51	17	12	1.42	397	193	67
18	M	62	37	43	43.00	48	17	13	1.31	381	214	62
19	M	55	34	50	80.00	42	32	16	2.00	686	394	76
20	F	71	32	49	82.00	45	15	15	1.00	346	215	68
21	F	64	37	45	55.00	52	13	12	1.08	331	186	67
22	F	48	31	32	40.00	43	15	10	1.50	246	129	67

Parameter	Mean	Median	Standard deviation	Minimum	Maximum
AO (mm)	32.77	32.50	2.67	29	37
LA (mm)	44.59	44.00	7.46	32	58
iLA (mm/m²)	56.36	49.50	18.76	36	108
LVDD (mm)	43.64	43.00	4.87	36	52
IS (mm)	18.59	17.00	4.63	13	32
PW (mm)	12.64	12.00	2.63	8	19
IS/PW	1.50	1.42	0.33	1.00	2.12
LV mass (g)	341.86	343.00	113.85	189	686
Indexed LV mass (g/m²)	184.88	182.15	58.49	99	394
LVEDV (ml)	88.7	85.5	23.10	54	130
EF (%)	68.32	68.00	4.29	61	78

Time points	Pre	Post	Absolute Dif. [95% CI]	Relative Reduction % [95% CI]	p-value
Intraprocedural	78.2 ± 33.1	34.1 ± 28.5	-44.1 [-53.3; −34.9]	58.9 [51.1; 66.7]	<0.001
Outpatient	110.5 ± 41.5	45.7 ± 24.4	-60.9 [-80.7; −41.1]	52.0 [38.2; 65.8]	<0.001

Endpoints		Total
Pre- and Post-Immediate Intraoperative
	Immediate gradient reduction ≥ 50%	16/22 (72.7%)
	Post-immediate gradient ≤ 50 mmHg	19/22 (86.4%)
	Post-immediate gradient ≤ 30 mmHg	12/22 (54.5%)
	Gradient reduction ≥ 50% and Post-immediate gradient ≤ 50 mmHg	16/22 (72.7%)
	Gradient reduction ≥ 50% of Post-immediate gradient ≤ 30 mmHg	12/22 (54.5%)
Pre-Outpatient and 6-Months Post-Outpatient
	Gradient reduction in 6 months ≥ 50%	12/20 (60.0%)
	Gradient after 6 months ≤ 50 mmHg	12/20 (60.0%)
	Gradient after 5 months ≤ 30 mmHg	7/20 (35.0%)
	Gradient reduction in 6 months ≥ 50% and after 6 months gradient ≤ 50 mmHg	9/20 (45.0%)
	Gradient reduction in 6 months ≥ 50% and after 6 months gradient ≤ 30 mmHg	6/20 (30.0%)

	SEPTUM
SUCCESS	Category	N	Variation	Median	Mean (SD)		p-value
Immediate gradient dropped MORE than 50%	No	6	15 – 18	15	15.8	(1.3)	0.050
Immediate gradient dropped MORE than 50%	Yes	16	13 – 32	18	19.6	(5.0)	0.050
Immediate gradient dropped BELOW 50%	No	3	15 – 18	15	16.0	(1.7)	0.300
Immediate gradient dropped BELOW 50%	Yes	19	13 – 32	17	19.0	(4.8)	0.300
Immediate gradient dropped BELOW 30%	No	10	15 – 27	16	17.9	(4.2)	0.421
Immediate gradient dropped BELOW 30%	Yes	12	13 – 32	17.5	19.2	(5.0)	0.421
Immediate gradient dropped more than 50% and BELOW 50 mmHg	No	6	15 – 18	15	15.8	(1.3)	0.050
Immediate gradient dropped more than 50% and BELOW 50 mmHg	Yes	16	13 – 32	18	9.6	(5.0)	0.050
Immediate gradient dropped more than 50% and BELOW 30 mmHg	No	10	15 – 27	16	17.9	(4.2)	0.421
Immediate gradient dropped more than 50% and BELOW 30 mmHg	Yes	12	13 – 32	17.5	19.2	(5.0)	0.421
Success 6 months gradient DROPPED more than 50%	No	8	16 – 32	19	20.6	(5.2)	0.137
Success 6 months gradient DROPPED more than 50%	Yes	12	13 – 27	16.5	17.8	(4.2)	0.137
Success Gradient 6 months BELOW 50%	No	8	13 – 23	17.5	17.5	(3.1)	0.506
Success Gradient 6 months BELOW 50%	Yes	12	15 - 32	17.5	19.9	(5.4)	0.506
Success Gradient 6 months DROPPED Below 30 mmHg	No	13	13 – 32	18	19.1	(5.1)	0.984
Success Gradient 6 months DROPPED Below 30 mmHg	Yes	7	15 – 27	17	18.7	(4.1)	0.984
Success gradient 6 months dropped > 50% and below 50 mmHg	No	11	13 – 32	18	19.2	(5.1)	0.751
Success gradient 6 months dropped > 50% and below 50 mmHg	Yes	9	15 – 27	17	18.7	(4.4)	0.751
Success gradient 6 months dropped > 50% and below 30 mmHg	No	14	13 – 32	17.5	18.9	(5.0)	0.889
Success gradient 6 months dropped > 50% and below 30 mmHg	Yes	6	15 – 27	17.5	19.0	(4.4)	0.889

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Departamento de Imagem Cardiovascular da Sociedade Brasileira de Cardiolodia (DIC/SBC) Av. Marechal Câmara, 160, 3º andar, Sala: 330 - Centro. CEP: 20020-907. , Telefone: +55 (21) 3478-2700 - Rio de Janeiro - RJ - Brazil
E-mail: abcimaging@cardiol.br

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[TFN1] N: number of patients; SD: standard deviation; BMI: body mass index; HCM: hypertrophic cardiomyopathy; SD: Standard Deviation.