Obstructive and non-obstructive hypertrophic cardiomyopathy: clinical, electrocardiographic, and echocardiographic differences

AIM: The purpose of the study was to analyse echocardiographic, electrocardiographic and clinical variables in patients with hypertrophic cardiomyopathy, as well as to compare the possible differences between the non-obstructive (NOHCM) and the obstructive form (OHCM). METHOD: 44 consecutive patients were studied and diagnosed with hypertrophic cardiomyopathy (NOHCM 26 and OHCM 18). The following variables were analysed: 1) echocardiographic: right ventricle (RV), interventricular septum (IVS), posterior wall (pW), telediastolic and telesystolic diameter of the left ventricle (TDD-LV and TSD-LV), size of the left atrium (LA), systolic anterior motion of the mitral valve (SAM), mitral insufficiency and direction of the jet (MI and MIpW), mitral anular calcium (MAC), filling pattern (A > E); 2) electrocardiographic: repolarization disorders (RD), left ventricular hypertrophy (LVH), negative "T" waves in the precordial leads (T-), pathological "q" waves, super or ventricular arrhythmias (SA or VA), short PR, right or left bundle branch block (RBBB and LBBB), and 3) clinical: presence of dyspnea, angina, syncope, palpitations and response to treatment with beta-blockers (B-b) or Calcium-antagonists (C-A). RESULTS: There were no differences in age or sex between the obstructive and non-obstructive groups: 1) echocardiographic differences: there were none in RV, pW, TDD-LV, LA nor A > E wave. Significant differences were found (p < 0.05) in the rest of the variables; IVS (16 +/- 3 mm in NOHCM vs 22 +/- 5 mm in OHCM), TSD-LV (26 +/- 5 mm in NOHCM vs 22 +/- 6 mm in OHCM), SAM (38% in NOHCM vs 89% in OHCM), MI (19% in NOHCM vs 78% in OHCM), MIpW (20% in NOHCM vs 79% in OHCM), MAC (15% in NOHCM vs 44% in OHCM); 2) electrocardiographic differences: there were none in the presence of RD, pathological "q", VA, short PR, RBBB nor LBBB. The presence of "T" negatives was on the limit of significance in the precordial leads (31% in NOHCM vs 11% in OHCM; p = 0.09). Differences were found in the rest of the variables; LVH (58% in NOHCM vs 83% in OHCM), SA (50% in NOHCM vs 17% in OHCM); 3) clinical differences: there were none in the presence of dyspnea, angina, syncope or palpitations. Differences were found in the improvement with treatment; B-b (60% in NOHCM vs 57% in OHCM), C-A (100% in NOHCM vs 100% in OHCM). CONCLUSIONS: 1) in our patients, the most frequent cardiomyopathy is the non-obstructive one, with no predominance of age or sex; 2) in OHCM, IVS is much wider, with smaller TSD-LV, there is a greater incidence of MI, generally directed towards the posterior wall of the left atrium, and a larger tendency to calcify the mitral annulus; 3) the most frequent electrocardiographic abnormality is the alteration of repolarization. NOHCM has a greater incidence of SA and a lower degree of LVH with more prevalence of negative "T" waves in the precordial leads; 4) there are no clinical parameters differentiating the two groups, although the sustained improvement obtained with treatment is more likely to be produced by the calcium-antagonists than by beta-blockers in both types of cardiomyopathy.