Real time data acquisition with Bluetooth

I'm trying to acquire ECG signals real time using Bluetooth HC-05. In Arduino IDE I get 150 samples/second, but here I get 50-60 samples/seconds. The function drawnow its delaying my aquisition a lot and I lose a part of the signal. I tried drawnow limitrate but sometimes its giving me some random samples. Can I make it faster, I want to get 150 samples/second. And another question is how does that fscanf work? If "b" is an object can't i access every value received from the object like b.Value or something like that?

 b = instrfind('Type', 'bluetooth', 'Name', 'Bluetooth-HC-05:1', 'Tag', '');
 if isempty(b)
    b = Bluetooth('HC-05', 1);
else
    fclose(b);
    b = b(1);
end

fopen(b);
figure
h = animatedline;
ax = gca;
ax.YGrid = 'on';
i=1;
x = zeros();
stop = false;
startTime = datetime('now');
while ~stop
    % Read current voltage value
    x(1,i) = str2double(fscanf(b));   
    % Get current time
    t =  time2num((datetime('now') - startTime),'seconds');
    % Add points to animation
    addpoints(h,t,x(1,i))
    drawnow 
    i = i+1;     
end