Methods

We conducted a retrospective cohort study of patients with HC with coexisting hypertension referred to the SLRHC HC program from January 1995 to January 2011. Patients were referred for confirmation of diagnosis and treatment recommendations. Criteria for diagnosis of HC in this study were echocardiographic demonstration of a hypertrophied nondilated left ventricle ≥15 mm inappropriate for the degree of hypertension severity and only if ≥1 of the following 3 criteria were present: (1) dynamic left ventricular (LV) outflow tract (LVOT) obstruction due to systolic anterior motion of the mitral valve and mitral-septal contact at rest or with physiologic provocation, (2) echocardiographic abnormalities typical of HC and generally not seen in hypertensive heart disease (i.e., apical or apical-mid hypertrophy sparing the base, marked asymmetric hypertrophy with systolic anterior motion but with gradients <30 mm Hg, or severe asymmetric hypertrophy with mild hypertension), and (3) in patients with nonobstructive HC, ancillary supportive criteria were a family history of HC in a first-degree family member or genotype analysis showing an HC-related sarcomeric protein mutation.

Hypertension was diagnosed conservatively only if 1 or both of the following criteria were present at the initial evaluation: (1) the patient was being actively treated for an established diagnosis of hypertension with a vasodilator such as a dihydropyridine calcium channel blocker, an ACE inhibitor, or an ARB; a thiazide-type diuretic; or clonidine, and (2) the patient had elevated blood pressure readings, defined as systolic pressure ≥140 mm Hg and/or diastolic pressure ≥90 mm Hg, on 2 consecutive SLRHC clinic visits.

Demographic, clinical, and laboratory data were obtained by retrospective chart review. Blood pressure readings and medications were compared between the initial and the last visits. The study was approved by the institutional review board of St. Luke’s Roosevelt Hospital.

Maximal LV wall thickness was measured from parasternal long-axis and short-axis views on 2-dimensional echocardiography, as previously described. The initial and follow-up echocardiograms were specifically assessed for systolic anterior motion of the mitral valve and peak instantaneous LVOT gradients. The simplified Bernoulli equation was used to calculate LVOT gradient, and the highest instantaneous gradient was reported. Care was taken to separate LVOT signal from that of mitral regurgitation. In all patients, the LVOT gradient was measured in the supine left lateral decubitus position and during 3 separate Valsalva maneuvers and after standing, as previously reported. All patients capable of exercising underwent treadmill testing with the Bruce protocol and had gradients acquired after exercise. Patients were excluded from exercise if they had orthopedic disabilities or such severe heart failure symptoms that they were deemed incapable of performing even a modified, reduced treadmill protocol, or for rest gradients >80 mm Hg. Beta blockers were held the morning of the stress test, while other medications were continued. Post–stress exercise continuous-wave Doppler gradients from the apical views were acquired in the supine left lateral decubitus position within 30–60 seconds after the completion of exercise and then again 3 minutes later. Patients were deemed to be obstructed if the maximal peak instantaneous LVOT gradient (at rest or provoked, including postexercise) was ≥30 mm Hg. Patients with follow-up durations <30 days as well as those without follow-up echocardiographic data were excluded. Patients were also excluded if they had severe mitral regurgitation thought to be unrelated to systolic anterior motion, or severe aortic stenosis.

Patients underwent formal stratification for sudden death risk and implantation of implantable cardioverter-defibrillators if, after consideration, the benefits of implantation appeared to outweigh the risks. In patients with symptomatic obstructive HC, the initial treatment consisted of discontinuation of vasodilators (if the patient was taking a vasodilator) and administration of maximal tolerated doses of β blockers, nondihydropyridine calcium channel blockers, or both ( Figure 1 ). Beta blockade was the first-line therapy. In patients in whom hypertension was the main current problem, verapamil or diltiazem was started as needed and as heart rate permitted. If symptoms and elevated gradients persisted after β blockade or nondihydropyridine calcium channel blockade, controlled-release disopyramide was generally added as previously reported. A combination of all 3 agents was generally avoided unless the patient had a permanent pacemaker. Patients with symptoms refractory to pharmacologic management and rest or provoked gradients >50 mm Hg were referred for surgical myectomy. Alcohol septal ablation was reserved for patients with medical contraindications for surgery. DDD pacing with short atrioventricular delay and complete ventricular capture was applied selectively in specific conditions: (1) in elderly patients who failed pharmacologic therapy and who were deemed to not be good candidates for any other intervention, (2) when an implantable cardioverter-defibrillator was implanted for sudden death prevention in an obstructed patient with mild to moderate heart failure symptoms or syncope, and (3) for symptomatic bradycardia. In patients with persistent hypertension after the initial therapy as outlined, clonidine 0.1 mg once or twice daily was given. In patients with refractory hypertension, 12.5 mg (preferred) to 25 mg hydrochlorothiazide was continued or added, generally in association with triamterene.

General approach to patients with symptomatic HC and hypertension. AV = atrioventricular; CCB = calcium channel blocker.

We first assessed the reduction of LVOT gradient at rest and HC-related symptoms. Because many patients did not undergo repeat exercise testing for gradient provocation because symptoms diminished, we did not compare provoked LVOT gradients before and after treatment. Second, we examined the prevalence of hypertension control, defined as systolic pressure <140 mm Hg and diastolic pressure <90 mm Hg at the last visit, and compared blood pressure on the first visit and last visit. Symptoms were assessed by New York Heart Association functional class. Clinical outcomes included all-cause mortality, stroke, new-onset atrial fibrillation, acute coronary syndromes, and congestive heart failure hospitalizations.

Means and proportions are reported for the initial and follow-up visits. Continuous variables are reported as mean ± SD. Means were compared using Student’s t tests, and proportions were compared using chi-square tests and Fisher’s exact tests. Primary and secondary outcomes were analyzed separately for obstructed and nonobstructed patients. For that purpose, 2-sided paired Student’s t tests and Wilcoxon’s tests were used to compare 2 means, and McNemar’s tests were used to compare proportions. All analyses were performed using commercially available statistical software (SPSS for Windows version 16.0; SPSS, Inc., Chicago, Illinois).

Results

In this time period, 755 patients with HC had initial evaluation at SLRHC. One hundred fifteen patients (mean age 60 years, 58% men) met the eligibility criteria for the study and were included in the analysis, with a mean follow-up period of 36 ± 32 months (range 1 to 192). Patients with hypertension were older than the rest of the SLRHC cohort without hypertension (mean age 60 vs 53 years, p <0.01). The baseline characteristics for the entire cohort (115 patients) and separately for the obstructed (94 patients, mean rest gradient 48 mm Hg, provoked gradient 112 mm Hg) and nonobstructed (21 patients) groups are listed in Table 1 . Overall, patients carried a high burden of symptoms, the most common being dyspnea (75%). Sixty-two patients (54%) had hypertension (blood pressure ≥140/90 mm Hg) at the initial evaluation. Results are divided into obstructed and nonobstructed patient groups.

Because of our treatment strategy, there was a significant decrease in the number of patients treated with peripheral vasodilators such as ACE inhibitors or ARBs (42% vs 14%, p <0.01) and dihydropyridine calcium channel blockers (13% vs 4%, p = 0.03). More patients were treated with β blockers (62% vs 86%, p <0.01) at the last visit compared to the initial visit, and the doses were increased in 76% of patients who were taking β blockers at the initial evaluation ( Table 2 ). Disopyramide therapy was increased from 9% to 35% of patients. Despite optimal pharmacologic management, 21 obstructed patients (22%) required septal reduction therapy for symptoms and resistant gradients (surgical myectomy in 19 and alcohol septal ablation in 2). In 15 patients (16%), DDD pacing was used for gradient reduction.

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